Classifications

• • H—ELECTRICITY
  • H04—ELECTRIC COMMUNICATION TECHNIQUE
  • H04B—TRANSMISSION
  • H04B15/00—Suppression or limitation of noise or interference
  • H04B15/02—Reducing interference from electric apparatus by means located at or near the interfering apparatus
• • H—ELECTRICITY
  • H04—ELECTRIC COMMUNICATION TECHNIQUE
  • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
  • H04L12/00—Data switching networks
  • H04L12/28—Data switching networks characterised by path configuration, e.g. LAN [Local Area Networks] or WAN [Wide Area Networks]
  • H04L12/40—Bus networks
  • H04L12/40006—Architecture of a communication node
• • G—PHYSICS
  • G05—CONTROLLING; REGULATING
  • G05B—CONTROL OR REGULATING SYSTEMS IN GENERAL; FUNCTIONAL ELEMENTS OF SUCH SYSTEMS; MONITORING OR TESTING ARRANGEMENTS FOR SUCH SYSTEMS OR ELEMENTS
  • G05B23/00—Testing or monitoring of control systems or parts thereof
  • G05B23/02—Electric testing or monitoring
  • G05B23/0205—Electric testing or monitoring by means of a monitoring system capable of detecting and responding to faults
  • G05B23/0218—Electric testing or monitoring by means of a monitoring system capable of detecting and responding to faults characterised by the fault detection method dealing with either existing or incipient faults
  • G05B23/0256—Electric testing or monitoring by means of a monitoring system capable of detecting and responding to faults characterised by the fault detection method dealing with either existing or incipient faults injecting test signals and analyzing monitored process response, e.g. injecting the test signal while interrupting the normal operation of the monitored system; superimposing the test signal onto a control signal during normal operation of the monitored system
• • H—ELECTRICITY
  • H04—ELECTRIC COMMUNICATION TECHNIQUE
  • H04B—TRANSMISSION
  • H04B1/00—Details of transmission systems, not covered by a single one of groups H04B3/00 - H04B13/00; Details of transmission systems not characterised by the medium used for transmission
  • H04B1/38—Transceivers, i.e. devices in which transmitter and receiver form a structural unit and in which at least one part is used for functions of transmitting and receiving
  • H04B1/3822—Transceivers, i.e. devices in which transmitter and receiver form a structural unit and in which at least one part is used for functions of transmitting and receiving specially adapted for use in vehicles
• • H—ELECTRICITY
  • H04—ELECTRIC COMMUNICATION TECHNIQUE
  • H04B—TRANSMISSION
  • H04B15/00—Suppression or limitation of noise or interference
  • H04B15/005—Reducing noise, e.g. humm, from the supply
• • H—ELECTRICITY
  • H04—ELECTRIC COMMUNICATION TECHNIQUE
  • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
  • H04L25/00—Baseband systems
  • H04L25/38—Synchronous or start-stop systems, e.g. for Baudot code
  • H04L25/40—Transmitting circuits; Receiving circuits
  • H04L25/49—Transmitting circuits; Receiving circuits using code conversion at the transmitter; using predistortion; using insertion of idle bits for obtaining a desired frequency spectrum; using three or more amplitude levels ; Baseband coding techniques specific to data transmission systems
  • H04L25/4902—Pulse width modulation; Pulse position modulation
• • H—ELECTRICITY
  • H04—ELECTRIC COMMUNICATION TECHNIQUE
  • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
  • H04L25/00—Baseband systems
  • H04L25/38—Synchronous or start-stop systems, e.g. for Baudot code
  • H04L25/40—Transmitting circuits; Receiving circuits
  • H04L25/49—Transmitting circuits; Receiving circuits using code conversion at the transmitter; using predistortion; using insertion of idle bits for obtaining a desired frequency spectrum; using three or more amplitude levels ; Baseband coding techniques specific to data transmission systems
  • H04L25/4906—Transmitting circuits; Receiving circuits using code conversion at the transmitter; using predistortion; using insertion of idle bits for obtaining a desired frequency spectrum; using three or more amplitude levels ; Baseband coding techniques specific to data transmission systems using binary codes
• • H—ELECTRICITY
  • H04—ELECTRIC COMMUNICATION TECHNIQUE
  • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
  • H04L7/00—Arrangements for synchronising receiver with transmitter
  • H04L7/0008—Synchronisation information channels, e.g. clock distribution lines
  • H04L7/0012—Synchronisation information channels, e.g. clock distribution lines by comparing receiver clock with transmitter clock
• • H—ELECTRICITY
  • H04—ELECTRIC COMMUNICATION TECHNIQUE
  • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
  • H04L7/00—Arrangements for synchronising receiver with transmitter
  • H04L7/0016—Arrangements for synchronising receiver with transmitter correction of synchronization errors
  • H04L7/0033—Correction by delay
  • H04L7/0037—Delay of clock signal
• • G—PHYSICS
  • G05—CONTROLLING; REGULATING
  • G05B—CONTROL OR REGULATING SYSTEMS IN GENERAL; FUNCTIONAL ELEMENTS OF SUCH SYSTEMS; MONITORING OR TESTING ARRANGEMENTS FOR SUCH SYSTEMS OR ELEMENTS
  • G05B2219/00—Program-control systems
  • G05B2219/20—Pc systems
  • G05B2219/24—Pc safety
  • G05B2219/24065—Real time diagnostics

Definitions

• This disclosure relates to a transceiver for communication and a method for controlling communication.
• an apparatus provided with a plurality of electronically controllable devices, communication is performed between processors that individually control the devices.
• a vehicle such as an automobile is provided with an air conditioner, door mirrors, power windows, wipers, and other electronically controllable devices.
• a plurality of Electronic Control Units (ECU) that electronically control these devices are mounted in the vehicle. These ECUs are connected to each other by a bus and communicate according to a predetermined communication protocol.
• noise might be emitted by wiring in the bus that connects the ECUs.
• the emitted noise might affect other devices depending on the frequency band.
• a transceiver for communication includes a timing determiner configured to detect a fall from high level to low level of a bus signal generated by pulse width modulation of a clock signal and input from a communication bus; a transmission data signal delay adj uster configured to determine a second timing having a predetermined time difference from a first timing, the bus signal rising from the low level to the high level at the first timing; an encoder configured to extend a low level of the bus signal by changing a data signal to be output to the communication bus from high level to low level; and a timing adjustment circuit configured to change the data signal to the low level at the second timing.
• the transmission data signal delay adjuster may calculate the predetermined time difference with Equation (1) below:
• tdiff is the predetermined time difference
• fnotch ⁇ s a frequency at which a harmonic level is reduced
• n is a natural number
• the above aspect may further include a clock rise start detector configured to detect a start of rising from the low level of the bus signal; and a clock rise start determiner configured to determine the first timing based on a timing of the start of rising of the bus signal from the low level detected by the clock rise start detector.
• the above aspect may further include a first comparator configured to compare a signal level of the bus signal with a first reference voltage; a second comparator configured to compare the signal level with a second reference voltage different from the first reference voltage; and a clock rise start determiner configured to determine a timing of a start of rising from the low level of the bus signal based on a comparison result from the first comparator and the second comparator.
• the transmission data signal delay adjuster may determine the second timing to be after the fall of the bus signal.
• the above aspect may further include a first comparator configured to compare a signal level of the bus signal with a first reference voltage; a second comparator configured to compare the signal level with a second reference voltage different from the first reference voltage; and a clock fall end determiner configured to determine a timing of the fall of the bus signal based on a comparison result from the first comparator and the second comparator.
• the transmission data signal delay adjuster may determine the second timing to be earlier than a timing of a start of rising from the low level of the bus signal.
• the transmission data signal delay adjuster may determine a timing of a start of rising from the low level to the high level of the data signal to be a predetermined length of time after a timing of the fall of the bus signal.
• the transceiver for communication may be included in a node used in Clock Extension Peripheral Interface (CXPI) communication.
• CXPI Clock Extension Peripheral Interface
• the transceiver for communication may function as a slave node transceiver communicating with a master node transceiver over the communication bus (e.g. , such as a CXPI bus).
• a communication bus e.g. , such as a CXPI bus
• a method for controlling communication by a transceiver that communicates over a communication bus including: detecting a fall from high level to low level of a bus signal generated by pulse width modulation of a clock signal and input from the communication bus; determining a second timing having a predetermined time difference from a first timing, the bus signal rising from the low level to the high level at the first timing; extending a low level of the bus signal by changing a data signal to be output to the communication bus from high level to low level; and changing the data signal to the low level at the second timing.
• the predetermined time difference may be calculated with Equation (2) below:
• tdiff is the predetermined time difference
• fnotch ⁇ s a frequency at which a harmonic level is reduced
• n is a natural number
• the above aspect may further include detecting by a clock rise start detector a start of rising from the low level of the bus signal; and determining the first timing based on a timing of the bus signal detected by the clock rise start detector.
• the transceiver for communication may include a first comparator and a second comparator, and the above aspect may further include: the first comparator comparing a signal level of the bus signal with a first reference voltage; the second comparator comparing the signal level with a second reference voltage different from the first reference voltage; and determining a timing of a start of rising from the low level of the bus signal based on a comparison result from the first comparator and the second comparator.
• the above aspect may further include determining the second timing to be after the fall of the bus signal.
• the transceiver for communication may include a first comparator and a second comparator, and the above aspect may further include: the first comparator comparing a signal level of the bus signal with a first reference voltage; the second comparator comparing the signal level with a second reference voltage different from the first reference voltage; and determining a timing of the fall of the bus signal based on a comparison result from the first comparator and the second comparator.
• the above aspect may further include determining the second timing to be earlier than a timing of a start of rising from the low level of the bus signal.
• the above aspect may further include determining a timing of a start of rising from the low level to the high level of the data signal to be a predetermined length of time after a timing of the fall of the bus signal.
• the transceiver for communication may be included in a node used in Clock Extension Peripheral Interface (CXPI) communication.
• CXPI Clock Extension Peripheral Interface
• the transceiver for communication may function as a slave node transceiver communicating with a master node transceiver over the communication bus (e.g. , such as CXPI bus).
• a slave node transceiver communicating with a master node transceiver over the communication bus (e.g. , such as CXPI bus).
• the transceiver for communication and the method for controlling communication of the embodiments below can reduce the effect of noise.
• FIG. 1 illustrates the relationship between control by a slave node and current flowing in the communication bus
• FIG. 2 illustrates an example of the spectrum of harmonic levels when executing control according to one of the disclosed embodiments
• FIG. 3 is a block diagram illustrating an example of a transceiver for communication according to this embodiment
• FIG. 4 illustrates an example of controlling a transmission data signal with the transceiver for communication according to this embodiment
• FIG. 5 illustrates the change in current of the communication bus when the slave fall end is sooner than the clock fall end
• FIG. 6 is a block diagram illustrating an example of a transceiver for communication according to a modification to this embodiment
• FIG. 7 illustrates a method of determining the time of the rise start and the time of the clock fall end in the transceiver for communication of FIG. 6;
• FIG. 8 illustrates processing by the clock fall end determiner in FIG. 6 for determining the time of the clock fall
• FIG. 9 illustrates an example of a method by which the transmission data signal delay adj uster in FIG. 6 determines the delay time
• FIG. 10 illustrates an example of a method by which the transmission data signal delay adj uster in FIG. 6 determines the delay time
• FIG. 11 illustrates a transmission data signal and a bus signal controlled by the decoder in FIG. 6;
• FIG. 12 illustrates a transmission data signal and a bus signal controlled by the decoder in FIG. 6;
• FIG. 13 illustrates the change in current of the communication bus when the rise start is sooner than the slave fall end
• FIG. 14 illustrates an example of the system structure in CXPI communication
• FIG. 15 illustrates an example of the circuit structure in a CXPI communication system
• FIG. 16 illustrates an example of the waveform for the master node in a CXPI communication system
• FIG. 17 illustrates a portion of the circuit within the CXPI transceiver of the master node in FIG. 15;
• FIG. 18 illustrates an example of the waveform for the slave node in a CXPI communication system
• FIG. 19 illustrates an example of the spectrum of noise generated in a CXPI communication system
• FIG. 20 illustrates an example of voltage on the communication bus
• FIG. 21 illustrates an example of current flowing in the communication bus
• FIG. 22 schematically illustrates an example of current flow in the communication bus
• FIG. 23 illustrates an example of the case when the inclination of the fall is set to be identical in the bus signal output by the master node and the bus signal output by the slave node.
• Examples of communication protocols used between ECUs mounted in an automobile include a Local Interconnect Network (LIN), a Controller Area Network (CAN), and a Clock Extension Peripheral Interface (CXPI).
• LIN Local Interconnect Network
• CAN Controller Area Network
• CXPI Clock Extension Peripheral Interface
• a communication system 1400 that performs CXPI communication includes one master node 1401 and a plurality of slave nodes 1402.
• FIG. 14 illustrates an example with three slave nodes 1402.
• the master node 1401 is connected to each slave node 1402 by a communication bus 1403.
• the master node 1401 and the slave nodes 1402 are, for example, each configured with a computer, computing device, or the like.
• the master node 1401 is a node that controls the operation timing of each slave node 1402.
• the master node 1401 transmits a bus signal mBUS (see FIG. 15), which becomes the reference for communication, at a constant frequency to the communication bus 1403.
• the slave nodes 1402 transmit and receive data with the bus signal mBUS transmitted by the master node 1401 as a reference clock.
• FIG. 15 illustrates an example of the circuit structure in a CXPI communication system.
• FIG. 15 only illustrates one slave node 1504 in order to simplify the illustration.
• a master node 1501 includes a microcontroller 1502 and a CXPI transceiver 1503.
• the slave node 1504 includes a microcontroller 1505 and a CXPI transceiver 1506.
• the microcontrollers 1502 and 1505 each include a Universal Asynchronous Receiver Transmitter (UART) interface and each transmit and receive signals to and from the CXPI transceivers 1503 and 1506.
• UART Universal Asynchronous Receiver Transmitter
• FIG. 16 illustrates an example of the waveform for the master node in a CXPI communication system.
• FIG. 16 illustrates the clock signal mCLK output from the microcontroller 1502 to the CXPI transceiver 1503, a data signal mTXD output from the microcontroller 1502 to the CXPI transceiver 1503, and the bus signal mBUS output by the CXPI transceiver 1503 to a communication bus 1507.
• a CXPI transceiver 1503 performs PWM on the clock signal mCLK to generate a signal exhibiting a logical value corresponding to the data signal mTXD.
• the bus signal mBUS generated by performing PWM on the clock signal mCLK is transmitted to the slave node 1504, thereby transmitting data from the master node 1501 to the slave node 1504.
• the bus signal mBUS has two voltage levels (high level and low level).
• the high level and the low level of the bus signal mBUS are generated by a circuit such as the one illustrated in FIG. 17 and are output to the communication bus 1507.
• the high level of the bus signal mBUS is determined by a pull-up resistor 1701 connected to a power line.
• the low level of the bus signal mBUS is generated by an output terminal to the communication bus 1507 being connected to a ground GND via a transistor Tr controlled by the data signal mTXD being input.
• the logical value of the bus signal mBUS output to the communication bus 1507 is determined by the length of the low level (or the high level) of the bus signal mBUS.
• the duration of the low level of the bus signal mBUS is shorter than a predetermined time, for example in the intervals Zi and Z2 in FIG. 16, the logical value of the bus signal mBUS is 1.
• the duration of the low level of the bus signal mBUS is longer than a predetermined time, for example in the interval Z3 in FIG. 16, the logical value of the bus signal mBUS is 0.
• the CXPI transceiver 1503 performs PWM on the clock signal mCLK so that the bus signal mBUS exhibits a logical value of 1 when the data signal mTXD is at a high level, as shown in the intervals Z i and Z2 in FIG. 16. Conversely, by extending the duration of the low level of the bus signal mBUS, the CXPI transceiver 1503 performs PWM on the clock signal mCLK so that the bus signal mBUS exhibits a logical value of 0 when the data signal mTXD is at a low level, as shown in the interval Z3 in FIG. 16. In this way, the CXPI transceiver 1503 transmits data by controlling the logical value of the bus signal mBUS based on the data signal mTXD.
• the CXPI transceiver 1503 receives a bus signal sBUS transmitted by the slave node 1504 from the communication bus 1507 and transmits a data signal obtained by decoding the bus signal sBUS to the microcontroller 1502 as a received signal mRXD.
• the slave node 1504 transmits data by combining the bus signal sBUS with the bus signal mBUS output by the master node 1501 to generate the bus signal BUS .
• the master node 1501 does not transmit data but rather transmits the bus signal mBUS at a constant duty cycle and receives the bus signal sBUS transmitted by the slave node 1504 from the communication bus 1507.
• the bus signal mBUS output by the master node 1501 is a signal with a logical value of 1. In other words, when the slave node 1504 does not output the bus signal sBUS, the bus signal BUS exhibits a logical value of 1.
• the slave node 1504 When outputting the bus signal sBUS, the slave node 1504 configures the bus signal sBUS so that the logical value of the combined bus signal BUS will be 0. By the slave node 1504 thus determining the logical value of the combined bus signal BUS based on the bus signal sBUS, data can be transmitted to the master node 1501 that acquires the bus signal BUS.
• FIG. 18 illustrates an example of the waveform for the slave node in the CXPI communication system.
• FIG. 18 illustrates a bus signal BUS that is a combination of the bus signal sBUS output from the slave node 1504 (CXPI transceiver 1506) and the bus signal mBUS output from the master node 1501 , a data signal sTXD output by the microcontroller 1505, a received data signal RXD acquired by the CXPI transceiver 1506 from the bus signal mBUS, and a transmission data signal TXD transmitted by the CXPI transceiver 1506 to the communication bus 1507.
• a bus signal BUS that is a combination of the bus signal sBUS output from the slave node 1504 (CXPI transceiver 1506) and the bus signal mBUS output from the master node 1501 , a data signal sTXD output by the microcontroller 1505, a received data signal RXD acquired by the CXPI transceiver 1506 from
• the slave node 1504 receives the bus signal mBUS output from the master node 1501 via the communication bus 1507 and operates.
• the CXPI transceiver 1506 acquires the clock signal sCLK from the bus signal mBUS acquired from the communication bus 1507 and outputs the clock signal sCLK to the microcontroller 1505.
• the slave node 1504 When transmitting data to the communication bus 1507, the slave node 1504 notifies other nodes of the start of data transmission by driving the bus signal mBUS acquired from the master node 1501. Transmission of data by the slave node 1504 is now described.
• the CXPI transceiver 1506 detects a fall in the bus signal mBUS by a change (fall) in the received data signal RXD, which is generated by a circuit inside the CXPI transceiver 1506 and the logical value of which changes in accordance with behavior of the bus signal mBUS ((i) in FIG. 18).
• the CXPI transceiver 1506 Upon detecting a fall in the bus signal mBUS by a fall in the received data signal RXD, the CXPI transceiver 1506 controls the logical value of the transmission data signal TXD generated in a circuit inside the CXPI transceiver 1506 to be 0 based on the data signal sTXD output by the microcontroller 1505 ((ii) in FIG. 18).
• the transmission data signal TXD being input into the communication bus 1507, the voltage of the bus signal sBUS drops to the low level while the logical value of the transmission data signal TXD is 0. Therefore, the duration of low level of the bus signal BUS that is the combination of the bus signal mBUS and the bus signal sBUS is extended ((iii) in FIG.
• the master node 1501 can receive a bus signal BUS with an extended low level, thereby detecting the start of data transmission from the slave node 1504 to the master node 1501 and starting to receive data.
• noise may be emitted from the communication bus 1507 by transmission and reception of signals.
• the noise emitted from the communication bus 1507 may affect other communication.
• a smart key system is affected by noise.
• a smart key system is a system whereby a key that the user possesses locks and unlocks doors of the automobile by wireless communication with the automobile.
• 134 kHz is the 7 th harmonic of 19.2 kHz. Therefore, as illustrated in FIG. 19, the harmonic level around 134 kHz (100 kHz to 160 kHz) indicated by region 1900 in the noise frequency spectrum increases. As a result, wireless communication of the smart key system may be blocked by CXPI communication.
• FIG. 20 illustrates an example of a voltage signal on the communication bus 1507
• FIG. 21 illustrates an example of current flowing in the communication bus 1507.
• FIG. 22 schematically illustrates an example of current flow in the communication bus 1507.
• the slave node 1504 sets the voltage level of the bus signal sBUS on the communication bus 1507 to a low level. Therefore, upon inputting the transmission data signal TXD to the communication bus 1507 (interval Z5 in FIG. 20 and FIG. 21 ), the current flows in the CXPI transceiver 1503 as indicated by (1 ) of FIG. 22 and also flows to the CXPI transceiver 1506 as indicated by (2). In other words, at this time, current flows in the communication bus 1507. When transitioning in this way from interval Z4 to interval Z5, conduction noise is generated due to the change in the current.
• the bus signal sBUS input to the communication bus 1507 at this time has a steeper inclination at the falling edge than the falling edge of the bus signal mBUS output from the master node 1501 , as illustrated in FIG. 20. Therefore, a sudden change in current occurs.
• the bus signal mBUS output by the master node 1501 is high level and the voltage level of the bus signal sBUS output from the slave node 1504 is maintained at low level (interval ⁇ in FIG. 20 and FIG. 21 ), the current stops flowing to the transistor Tr side of the CXPI transceiver 1503, and as indicated by (2) in FIG.
• FIG. 23 illustrates an example of the case when the inclination of the fall is set to be identical in the bus signal mBUS output by the master node 1501 and the bus signal sBUS output by the slave node 1504.
• the bus signal BUS which is a combination of the bus signal mBUS from the master node 1501 and the bus signal sBUS from the slave node 1504 and which flows in the communication bus 1507
• an interval Z7 may occur, in which the signal level rises and falls in correspondence with the rise of the bus signal mBUS from the master node 1501 and the fall of the bus signal sBUS from the slave node 1504.
• FIG. 1 illustrates the relationship between control by a slave node and current flowing in the communication bus.
• FIG. 1 illustrates a bus signal mBUS output by the master node 1501 , a bus signal sBUS output by the slave node 1504, a bus signal BUS that is a combination of the bus signal mBUS and the bus signal sBUS, and the current IBUS flowing in the communication bus 1507.
• a bus signal mBUS output by the master node 1501 illustrates a bus signal sBUS output by the slave node 1504
• a bus signal BUS that is a combination of the bus signal mBUS and the bus signal sBUS
• time ti indicates the point in time at which the logical value of the bus signal sBUS from the slave node 1 504 reaches 0 (slave fall end), and time t2 indicates the point in time at which the bus signal mBUS from the master node 1501 starts to be displaced from the low level to the high level (clock rise start).
• the current IBUS flowing in the communication bus 1507 changes due to the operations when the slave node 1504 transmits data.
• section A indicates the change in the current IBUS due to the transition from interval Z4 to interval Z5 in FIGS . 20 and 21
• section B indicates the change in the current IBUS due to the transition from interval Z5 to interval ⁇ in FIGS . 20 and 21 .
• a time difference tdiff is a predetermined length, where tdiff is the difference between time t 2 and time ti, then in a specific frequency band, a component of the current spectrum in section A and a component of the current spectrum in section B are canceled due to a phase relationship .
• Equation (3) The phase difference ⁇ in the frequency components of section A and section B at a predetermined frequency f is represented by Equation (3) below.
• Equation (4) for fnotch and tdiff yields Equation (5) and Equation (6) below.
• fnotch (2n- l )/(2tdiff) (5)
• FIG. 2 illustrates an example of the frequency spectrum of harmonic levels when executing control according to this embodiment.
• the effect of conduction noise at the frequency band near f no tch can be reduced.
• the difference in height i . e. the fluctuation range of the current
• FIG. 3 is a block diagram illustrating an example of a slave node transceiver for communication (CXPI transceiver 1506), according to this embodiment, which can reduce the above-described harmonic level.
• the CXPI transceiver 1506 includes an analog block 301 and a logic block 305.
• the analog block 301 includes a driver 302, a receiver 303 , and a clock rise start detector 304.
• the driver 302 inputs the transmission data signal TXD from the microcontroller 1505 , acquired via the logic block 305 , into the communication bus 1507.
• the receiver 303 acquires the bus signal mBUS input from the communication bus 1 507 connected to the analog block 301 and transmits the bus signal mBUS to the logic block 305.
• the clock rise start detector 304 is a circuit that detects the point in time at which the clock signal starts to be displaced from the low level to the high level, i . e. the time t2.
• the clock rise start detector 304 is, for example, configured with a comparator.
• the clock rise start detector 304 is configured with a comparator, for example the low level voltage VL of the bus signal mBUS and the bus signal mBUS are input into the clock rise start detector 304.
• the clock rise start detector 304 compares the voltage VL with the voltage of the bus signal mBUS that are input and outputs a signal representing the comparison result.
• the logic block 305 includes a decoder 306, a clock rise start determiner 307, a transmission data signal delay adj uster 308, and an encoder 309.
• the decoder 306 transmits the result of decoding the signal acquired from the receiver 303 to the microcontroller 1 505.
• the clock rise start determiner 307 determines the time t2 at which the bus signal mBUS starts to be displaced from the low level. Based on the time t2 acquired from the clock rise start determiner 307 and on the target time difference tdiff, the transmission data signal delay adj uster 308 determines the timing for inputting the transmission data signal TXD, i. e. the timing for lowering the bus signal sBUS from the slave node 1 504.
• the encoder 309 converts the data signal sTXD acquired from the microcontroller 1 505 to a PWM signal and inputs the transmission data signal TXD to the driver 302. At this time, the encoder 309 inputs the transmission data signal TXD to the driver 302 at a predetermined timing based on the timing for inputting the transmission data signal TXD determined by the transmission data signal delay adj uster 308.
• FIG. 4 illustrates a bus signal mBUS output by the master node 1 501 , a bus signal sBUS output by the slave node 1 504, a bus signal BUS that is a combination of the bus signal mBUS and the bus signal sBUS, and the current IBUS flowing in the communication bus 1 507.
• a bus signal mBUS output by the master node 1 501 a bus signal sBUS output by the slave node 1 504
• a bus signal BUS that is a combination of the bus signal mBUS and the bus signal sBUS
• the CXPI transceiver 1506 need not detect the time t 2 _ n -i if the time t 2 _ n of the n th clock rise start can be calculated.
• the CXPI transceiver 1506 may calculate the time t2_ n based on the time t2_ n - m of the (n-m) th clock rise start (where n > m).
• the CXPI transceiver 1506 subtracts the time difference tdiff from the time t2_n with the transmission data signal delay adj uster 308, thereby calculating the time at which the logical value of the bus signal sBUS became 0, i. e. the time ti_ n of the slave fall end.
• the CXPI transceiver 1506 modulates the bus signal sBUS with logical value 0 to a PWM signal so that the time ti_ n becomes the slave fall end of the bus signal sBUS .
• the harmonic level at a predetermined frequency fnotch can be reduced.
• FIG. 5 illustrates the change in current of the communication bus when the slave fall end is sooner than the clock fall end.
• the time ti of the slave fall end of the bus signal sBUS is earlier than the time to of the clock fall end of the bus signal mBUS, then from the time ti to the time to, all of the current flows from the pull-up resistor side of the master node 1501 to the slave node 1504 via the communication bus 1507. Therefore, a change in the current IBUS of the communication bus 1507 occurs. Conduction noise is generated due to this change in current IBUS.
• the amount of change in the current IBUS at this time is the total of the amount of change in section A and section B in FIG. 1. Therefore, the effect on conduction noise at this time increases more in comparison to section A and section B in FIG. 1 . Accordingly, the time ti of the slave fall end should preferably be later than the time to of clock fall end.
• FIG. 6 is a block diagram illustrating an example of a transceiver for communication (CXPI transceiver 1506) according to a modification to this embodiment.
• the CXPI transceiver 1506 according to this modification includes an analog block 601 and a logic block 605.
• the analog block 601 includes a driver 602, a first comparator 603, and a second comparator 604.
• the driver 602 inputs the transmission data signal TXD from the microcontroller 1505, acquired via the logic block 605, into the communication bus 1507.
• the first comparator 603 and the second comparator 604 output a signal used in the logic block 605 to determine the time of the clock rise start and the clock fall end.
• the bus signal mBUS from the communication bus 1507 is input into the first comparator 603 and the second comparator 604. Furthermore, a first reference voltage Vthi is input into the first comparator 603, and a second reference voltage Vth2 is input into the second comparator 604.
• the first reference voltage Vthi and the second reference voltage Vth2 are each equal to or greater than the voltage VL of the low level and equal to or less than the voltage VH of the high level of the bus signal mBUS . It is assumed here that Vthi > Vth2.
• the first comparator 603 and the second comparator 604 respectively compare the first reference voltage Vthi and the second reference voltage Vth2 with the voltage of the bus signal mBUS and output a signal representing the comparison result (comparison signal).
• the logic block 605 includes a clock rise start determiner 606, a clock fall end determiner 607, a transmission data signal delay adj uster 608, and an encoder 609.
• the comparison signals from the first comparator 603 and the second comparator 604 are input into the clock rise start determiner 606 and the clock fall end determiner 607.
• the clock rise start determiner 606 determines the time t at which the bus signal mBUS starts to be displaced from the low level.
• the clock fall end determiner 607 determines the time to at which the bus signal mBUS reaches the low level. Details on the method by which the clock rise start determiner 606 and the clock fall end determiner 607 determine the time t2 and the time to are provided below.
• the transmission data signal delay adj uster 608 determines the timing for inputting the transmission data signal TXD.
• the transmission data signal delay adj uster 608 performs control so that the time t i of the slave fall end is earlier than the time t2 of the clock rise start by the time difference tdiff that allows the desired harmonic level to be reduced.
• the time ti is earlier than the time to of the clock fall end, however, conduction noise is generated for the reason described with reference to FIG. 5.
• the time ti of the slave fall end may be controlled to be at or later than the time to.
• the encoder 609 converts the data signal sTXD acquired from the microcontroller 1505 to a PWM signal and inputs the transmission data signal TXD to the driver 602.
• the encoder 609 inputs the transmission data signal TXD acquired from the microcontroller 1505 to the driver 602 at a predetermined timing based on the timing for inputting the transmission data signal TXD determined by the transmission data signal delay adj uster 608.
• FIG. 7 illustrates the bus signal mBUS, a comparison signal Comp l of the first comparator 603, and a comparison signal Comp2 of the second comparator 604.
• the clock rise start determiner 606 determines a time tri at which the bus signal mBUS reached the voltage Vth2 and a time t r2 at which the bus signal mBUS reached the voltage Vthi while transitioning from low level to high level. Based on the voltages Vth2 and Vthi of the bus signal mBUS and the times t r i and t r2 , the clock rise start determiner 606 can calculate the rate of change of the bus signal mBUS . Specifically, the rate of change is calculated as (Vthi-Vth 2 )/(t r2 -t r i).
• the clock fall end determiner 607 determines a time tn at which the bus signal mBUS reached the voltage Vthi and a time tn at which the bus signal mBUS reached the voltage Vth2 while transitioning from high level to low level. Based on the voltages Vthi and Vth2 of the bus signal mBUS and the times tn and tn, the clock fall end determiner 607 can calculate the rate of change of the bus signal mBUS .
• the rate of change is calculated as (Vth2 _ Vthi)/(tf2-tn).
• the CXPI transceiver 1506 determines the ti 1T1G 12 n of the n th clock rise start with the clock rise start determiner 606.
• the method for determination of the clock rise start determiner 606 is similar to the method described in FIG. 4. Hence, details are omitted here.
• the clock rise start determiner 606 can determine the time of the clock rise start with the method described with reference to FIG. 7.
• the CXPI transceiver 1506 determines the time to_ n of the n th clock fall end of the bus signal mBUS. Specifically, as illustrated in FIG. 8, the clock fall end determiner 607 detects the time to_n-i of the clock fall end of the bus signal mBUS at the (n-l ) th cycle that is one cycle before the n th cycle. The clock fall end determiner 607 detects the time to n-i with the method described with reference to FIG. 7.
• the CXPI transceiver 1506 also determines the time of the delay of the transmission data signal TXD with the transmission data signal delay adj uster 608. Details on the method by which the transmission data signal delay adj uster 608 determines the delay time are provided with reference to FIG. 9 and FIG. 10.
• FIG. 9 and FIG. 10 illustrate an example of a method by which the transmission data signal delay adj uster in FIG. 6 determines the delay time.
• FIG. 9 and FIG. 10 illustrate the bus signal mBUS, the transmission data signal TXD (not controlled) when not controlling the timing of output, and the transmission data signal TXD when controlling the timing of output.
• the time tn at which the voltage becomes Vthi when the bus signal mBUS falls is described as being a reference time.
• Dint is a delay value within the circuit and includes a comparator delay, an internal circuit delay, a bus output delay, and the like. Furthermore, tdly is the delay time.
• the transmission data signal delay adj uster 608 determines t ⁇ ji y by Equation (9) below.
• FIG. 9 illustrates an example of a state in which Equation (9) holds.
• the CXPI transceiver 1506 controls the transmission data signal TXD based on the calculated delay time t ⁇ ji y .
• FIG. 11 and FIG. 12 illustrate the transmission data signal TXD controlled by the encoder 609 in FIG. 6, and the bus signal BUS yielded by combining the bus signal mBUS and the bus signal sBUS.
• FIG. 11 illustrates the results of control when tdiff ⁇ t 2 -to
• FIG. 12 illustrates the results of control when tdiff > t 2 -to.
• the encoder 609 converts the transmission data signal TXD with logical value 0 to a PWM signal and outputs the result. At this time, with respect to the fall of the transmission data signal TXD, the encoder 609 performs control for a time delay corresponding to t ⁇ ji y . On the other hand, with respect to the time at which the transmission data signal TXD starts to rise (slave rise start), the encoder 609 performs control so that the length of time from the time tn is a constant length of time.
• the encoder 609 controls the transmission data signal to rise after a constant length of time from the time to. In this way, the CXPI transceiver 1506 can reduce the harmonic level at a desired frequency band while maintaining the duty cycle of the bus signal BUS.
• the time ti of the slave fall end is later than the time t 2 at which the clock signal starts to be displaced from the low level to the high level, then the current flowing in the communication bus 1507 suddenly changes as illustrated in FIG. 13, generating conduction noise. Accordingly, the time ti should preferably be earlier than the time t 2 . According to the above-described embodiment and modification, the time ti is controlled to be earlier than the time t 2 .
• the encoder may generate a PWM signal, and a timing adj ustment circuit provided separately in the CXPI transceiver 1506 may perform control to delay the falling edge of the control signal (slave fall end).
• a timing adj ustment circuit provided separately in the CXPI transceiver 1506 may perform control to delay the falling edge of the control signal (slave fall end).
• the function of the timing adj ustment circuit has been described as being included in the encoder.
• clock rise start determiner 307 may be configured as a logic circuit or the like in which a plurality of logic cells are combined. Specific examples include one or more of each of the following: an Application Specific Integrated Circuit (ASIC), Digital Signal Processor (DSP), Digital Signal Processing Device (DSPD), Programmable Logical Device (PLD), Field Programmable Array (FPGA), System-on-Chip (SoC), processor, controller, microcontroller, and microprocessor, or a combination thereof.
• ASIC Application Specific Integrated Circuit
• DSP Digital Signal Processor
• DSPD Digital Signal Processing Device
• PLD Programmable Logical Device
• FPGA Field Programmable Array
• SoC System-on-Chip
• Various embodiments described herein may include various operations. These operations may be performed and/or controlled by hardware components, digital hardware and/or firmware, and/or combinations thereof.
• the term "coupled to” may mean coupled directly or indirectly through one or more intervening components. Any of the signals described herein may be time multiplexed with other signals and provided over one or more common buses. Additionally, the interconnection between circuit components or blocks may be shown as buses or as single signal lines. Each of the buses may alternatively be one or more single signal lines and each of the single signal lines may alternatively be buses.
• Certain embodiments may be implemented as a firmware or software product that may include instructions stored on a non-transitory computer-readable medium, e.g. , such as volatile memory and/or non-volatile memory. These instructions may be used to program one or more devices that include one or more general-purpose or special-purpose processors (e. g. , such as CPUs, ASICs, DSPs, DSPDs, PLDs, FPGAs, SoCs, etc.) or equivalents thereof (e. g. , such as processing cores, processing engines, microcontrollers, and the like), so that when executed by the processor(s) or the equivalents thereof, the instructions cause the device(s) to perform the operations described herein.
• general-purpose or special-purpose processors e. g. , such as CPUs, ASICs, DSPs, DSPDs, PLDs, FPGAs, SoCs, etc.
• equivalents thereof e. g. , such as processing cores, processing engines, micro
• a non-transitory computer-readable storage medium may include, but is not limited to, electromagnetic storage medium (e. g. , floppy disks, hard disks, and the like), optical storage medium (e.g. , CD-ROM), magneto-optical storage medium, read-only memory (ROM), random-access memory (RAM), erasable programmable memory (e.g., EPROM and EEPROM), flash memory, or another now-known or later-developed non-transitory type of medium that is suitable for storing information.
• a computer-readable medium may also include one or more mechanisms for storing or transmitting information in a form (e.g. , software, processing application, etc.) that is readable by a machine (e.g., such as a device or a computer).

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