JPH10301899A - Electronic equipment and interface circuit - Google Patents

Abstract

PROBLEM TO BE SOLVED: To make it possible to use the electronic equipment even as both a host and a guest without providing two interfaces. SOLUTION: Relating to the electronic equipment having the interface circuit for connecting other equipment, the interface circuit is equipped with a USB (universal serial bus) connector 30 provided with terminals for connecting data lines D+ and D0- and a power line (Vcc, GND), a power source part 32 for supplying electric power through the power line, a switching part 32 which selectively connects pull-up resistances(R2) 44 and 48 and pull-down resistances(R 1) 46 and 49 to the data lines D+ and D- respectively and switches the connection between the power source part 32 and power line (Vcc), and a USB control part 38 which controls the switching of the connections of the pull-up resistances(R2) and pull-down resistances(R1) with the data lines D+ and D- and the connection fo the power source part 32 with the power line (Vcc).

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to an electronic device for connecting peripheral devices such as a keyboard, a mouse, a speaker, a modem, and a printer, and an interface circuit.

[0002]

2. Description of the Related Art In recent years, Universal Serial Bus (USB) has begun to be used as a standard for connecting peripheral devices such as a keyboard, a mouse, a speaker, a modem, and a printer. The USB interface allows an interface that differs for each peripheral device to be easily connected to a host such as a personal computer by the same interface connector.

In the USB interface, there is always one host (a personal computer or the like), and peripheral devices (logical functions are called functions) can be connected to this host to transmit and receive data. With the USB interface, a peripheral device (function) can be further connected to itself by providing a hub.

FIG. 6 shows an example of a connection form between a host 80 and a peripheral device 82 using a conventional USB interface. The USB interface includes a host interface and a peripheral interface, and peripheral interfaces include a high-speed transfer interface (full speed) and a low-speed transfer interface (low speed).

FIG. 6A shows a configuration in which a host 80 and a peripheral device 82 (full-speed function) for high-speed transfer are connected via a cable 84. A USB circuit (transceiver) 86 is provided in the host 80, and a USB circuit (transceiver) 90 is provided in the peripheral device 82.
Is provided.

[0006] There are two USB data lines (D +, D
−), Pull-down resistors (R1) 88 and 89 are connected to the respective data lines on the host 80 side. On the other hand, on the peripheral device 82 side, the pull-up resistor (R2) 91 is connected to the D + data line because of the full-speed function. According to the USB interface standard, the pull-down resistor (R1) is 15 kΩ ± 5
%, And the pull-up resistance (R2) is 1.5 kΩ ± 5%.

FIG. 6B shows a configuration in which a host 80 and a peripheral device 92 (low-speed function) for performing low-speed transfer are connected via a cable 94. The host 80 is the same as that shown in FIG. 6A. A USB circuit (transceiver) 86 is provided, and pull-down resistors (R1) 88 and 89 are connected to each data line. on the other hand,
On the peripheral device 92 side, since it is a low-speed function, a pull-up resistor (R
2) 95 is connected.

[0008]

As described above, the conventional US
The B interface has a configuration in which pull-down resistors (R1) 88 and 89 are connected to respective data lines on the host 80 side, and a pull-up resistor (R2) 91 is connected to one data line D + in the peripheral device 82 that performs high-speed transfer. The peripheral device 92 that performs low-speed transfer has a configuration (standard) in which the other data line D-pull-up resistor (R2) 95 is connected.

That is, the configuration of the interface circuit differs depending on whether the device is a host or a peripheral device, and whether the peripheral device performs high-speed transfer or low-speed transfer.

If an electronic device or a peripheral device is used in a fixed manner as a host or a peripheral device,
It is only necessary to provide one connector conforming to the B interface.

In recent years, however, devices that can be both hosts and peripheral devices, for example, portable electronic devices (for example, handheld personal computers (HPCs)) have begun to be widely used.

In general, portable electronic devices (HPCs)
A personal computer or the like can be used as a host to directly connect and function as a peripheral device for transmitting and receiving data, or connect a peripheral device such as a modem or a printer to function as a host for communication or printing. is there.

Therefore, an electronic device (HPC) is a peripheral device,
If any of the hosts is to function, the use of the USB interface requires the provision of two connectors for the host and peripheral devices.

[0014] For this reason, a space for two interfaces (connectors) is required in the housing in configuring the electronic device (HPC), and the cost is also required for two.

[0015] The present invention has been made in view of the above-described circumstances, and an electronic device and an interface that can be used as a host and a peripheral device without providing two interfaces. It is intended to provide a circuit.

[0016]

According to the present invention, there is provided an electronic device having an interface circuit for connecting another device, wherein the interface circuit comprises a first terminal for connecting two data lines and a power supply. A connector provided with a second terminal for connecting a line, power supply means for supplying power through a power supply line connected to the second terminal of the connector, and a connector connected to the first terminal of the connector Selectively connect a pull-up resistor and a pull-down resistor to each of the data lines
Switching means for switching the connection between the power supply means and the second terminal of the connector; connection of a pull-up resistor and a pull-down resistor to the data line by the switching means; and connection between the power supply means and a second terminal of the connector. And control means for controlling switching of the connection.

According to this, when the device to be connected functions as a host according to the USB interface standard, data can be transferred as a peripheral device by connecting the pull-up resistor to the data line, and the device to be connected can be connected to the data line. When functioning as a peripheral device, data can be transferred as a host by connecting a pull-down resistor to a data line. In addition, power is also supplied to peripheral devices when the own device functions as a host,
When functioning as a peripheral device, it can take in power supplied from the host.

[0018] The apparatus further comprises detection means for detecting whether the connected device functions as a host or a peripheral device with respect to the device itself, and wherein the control means determines the connection result as a result of the detection by the detection means. When the connected device functions as a host, a pull-up resistor is connected to the data line in the switching means, and when the connected device functions as a peripheral device, a pull-down resistor is connected to the data line in the switching device. It is characterized by the following.

Further, the detecting means detects whether the connected device functions as a host or a peripheral device with respect to the own device based on the signal level of the data line.

The detecting means applies a resistor for applying a constant load to the power supply line, and a load by the resistor, and determines whether the connected device is connected to its own device based on the presence or absence of a voltage drop at this time. And a circuit for detecting whether the device functions as a host or a peripheral device.

Also, in an interface circuit for connecting another device, a connector provided with a first terminal for connecting two data lines and a second terminal for connecting a power supply line, Power supply means for supplying power through a power supply line connected to a first terminal of the connector; and a pull-up resistor and a pull-down resistor for each of data lines connected to the first terminal of the connector. Switching means for selectively connecting the power supply means and the second terminal of the connector; a transceiver for transmitting or receiving data through the two data lines; Connection of an up resistor and a pull down resistor to the data line;
And control means for controlling switching of connection with the terminal and controlling transmission and reception of data by the transceiver.

[0022]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a block diagram illustrating a schematic configuration of an electronic device according to the present embodiment. As shown in FIG. 1, the electronic device according to the present embodiment includes a CPU 1
0, a memory 12, an external storage device 14, a display device 16, an input device 17, and an interface circuit 19. The electronic device shown in FIG. 1 is a device that can be a host or a peripheral device, for example, a portable electronic device (HP
C).

The CPU 10 controls the entire electronic device and executes various processes according to programs stored in the memory 12. The CPU 10 causes the electronic device to function as, for example, a peripheral device for a personal computer or a host for peripheral devices such as a keyboard, a mouse, a modem, and a printer.

The memory 12 stores programs, data, and the like that define the operation of the CPU 10. External storage device 14
Is composed of a hard disk device, etc.
Stores programs and data.

The display device 16 is constituted by a liquid crystal display or the like, and performs display related to various processes. The input device 17 includes a keyboard, a mouse, and the like, and inputs codes, data, and the like for processing executed by the electronic device.

The interface circuit 19 connects the electronic device to a device functioning as a host (such as a personal computer) or a peripheral device, and basically conforms to the USB (Universal Serial Bus) standard. It was done.

However, in the USB standard, the configuration of the interface circuit differs depending on whether the device is a host or a peripheral device, and in the case of a peripheral device whether high-speed transfer or low-speed transfer is performed. The interface circuit 19 has a configuration capable of coping with any case depending on the device to be connected. The detailed configuration will be described later.

FIG. 2 shows an example of a connection form between the peripheral device 22 and another device via the interface circuit 19 in the present embodiment. FIG. 2A shows the electronic device 20.
In this configuration, the peripheral device 22 (which may be a full-speed function or a low-speed function) is connected via a cable 23. In this case, the electronic device 20 functions as a host for the peripheral device 22.

FIG. 2B shows a configuration in which an electronic device 20 and a personal computer 24 are connected via a cable 23. In this case, the electronic device 20 functions as a peripheral device for the personal computer 24 as a host.

Cable 23 for connecting electronic device 20 to peripheral device 22 or personal computer 24
Has two USB data lines (D +, D-),
Two power supply lines (Vcc, GND) for power supply are included.

FIG. 3 shows a detailed configuration of the interface circuit 19. As shown in FIG. 3, the interface circuit 19 in the present embodiment includes a USB connector 30,
Power supply unit 32, switching unit 34, USB transceiver unit 3
6 and each functional unit of a USB control unit 38 (controller).

The USB connector 30 has a shape conforming to the USB standard, and a cable 23 for connecting a data line and a power supply line to a peripheral device 22 or a personal computer 24 is connected thereto. USB connector 3
0 is the terminal D +, D-, Vcc, GND for each line.
Is provided. The USB connector 30 is connected to the electronic device 2
One is provided for 0.

The power supply unit 32 controls power supply to and from a device connected via a power supply line by the USB connector 30 and a pull-up resistor (switching) connected to a data line when the electronic device 20 functions as a host. Part 3
4) is supplied.

In the USB, power is supplied from a device functioning as a host to peripheral devices. For this purpose, the power supply section 32 is provided with a power supply circuit 40, a power supply protection diode 41 is connected to a power supply terminal P1, and a power supply protection diode 4 is connected to a power supply and demand terminal P2.
2 are connected. The diode 41 is connected to the switching unit 3
4 is connected to the terminal Vcc of the USB connector 30 via the switch SW5, and the diode 42 is directly connected to the terminal Vcc of the USB connector 30. The power supply circuit 4
The terminal P3 of 0 is connected to the terminal GND of the USB connector 30 and the switch SW2 of the switching unit 34.

The switching unit 34 performs high-speed transfer according to the device connected by the cable 23 connected to the USB connector 30, whether the own device functions as a host or a peripheral device, and when the device functions as a peripheral device. The data lines D + and D + connected to the terminals D + and D-
For D-, the connection is switched to either the pull-up resistor or the pull-down resistor, and the switching unit 34 switches the connection between the terminal Vcc of the USB connector 30 and the diode 41.

The switching unit 34 includes a USB connector 30
Pull-up resistor (R2) 44 and pull-down resistor (R1) 4 for data line D + connected to terminal D +
6. A pull-up resistor (R2) 48 and a pull-down resistor (R1) 49 for the data line D- connected to the terminal D- of the USB connector 30 are provided.

The switch SW1 is connected to the pull-up resistor (R2) 44, the switch SW2 is connected to the pull-down resistor (R1) 46, and the switch S is connected to the pull-up resistor (R2) 48.
W3, pull-down resistor (R1) 49 has switch SW4
Are provided, and switching is controlled by the USB control unit 38, respectively.

The switch SW1 is controlled by a signal on the signal line PV + from the USB controller 38.
A line for supplying pull-up power supplied from the power supply circuit 40 when turned on, and a pull-up resistor (R2) 4
4 and the pull-up resistor (R2) 44 is connected to the data line D +.

The switch SW2 is controlled by a signal on the signal line PVG from the USB controller 38.
When turned on, the terminal P3 of the power supply circuit 40, the GND terminal of the USB connector 30, and the pull-down resistor (R1) 46
And the pull-down resistor (R1) 46 is connected to the data line D +.

The switch SW3 is controlled by a signal on the signal line PV- from the USB control unit 38.
A line for supplying pull-up power supplied from the power supply circuit 40 when turned on, and a pull-up resistor (R2) 4
8 and the pull-up resistor (R2) 48 is connected to the data line D-.

The switch SW4 is controlled by a signal on the signal line PVG from the USB controller 38.
When turned on, the terminal P3 of the power supply circuit 40, the GND terminal of the USB connector 30 and the pull-down resistor (R1) 49
And the pull-down resistor (R1) 49 is connected to the data line D−.

The switching section 34 is provided with a switch SW5 between the terminal Vcc of the USB connector 30 and the diode 41. The switch SW5 is controlled by a signal on the signal line PVG from the USB control unit 38, and connects the terminal Vcc to the diode 41 when turned on.

The USB transceiver unit 36 is a basic component of the USB interface. The USB transceiver unit 36 is connected to the terminals D + and D- of the USB connector 30 via data lines D + and D-, and controls the USB control unit 38. With this, data transmission and reception and detection of single end zero (SE0) are performed. The USB transceiver unit 36 includes a differential driver 5
0, differential receiver 52, single-ended receiver 54,
56, and a NOR circuit 58 are provided. Differential driver 5
0, differential receiver 52, single-ended receiver 54,
56 is connected to data lines D + and D-, respectively.

The differential driver 50 is for data transmission, and the Xmt Data signal from the USB control unit 38, Force SE
A signal is output to the data lines D + and D- according to the 0 signal and the out enable (OE) signal.

The differential receiver 52 is for data reception, receives data according to the state of the signals on the data lines D + and D-, and outputs the data to the USB control unit 38 as an Rcv Data signal.

The single-ended receivers 54 and 56
The signal state of the data lines D + and D- connected to the terminals D + and D- of the SB connector 30 is held. The NOR circuit 58 outputs a signal corresponding to the state of the signal held by the single-ended receivers 54 and 56. When the state of the signal on the data lines D + and D- is low level "0", the NOR circuit 58 outputs the SE0 Detect signal. “1” is output to the USB control unit 38.

The USB control unit 38 controls PV +, PVG, PV for each of the switches SW1 to SW5 of the switching unit 34.
-Switching control by each signal of-, USB transceiver unit 3
6 data transmission and reception, single-ended zero (SE
0) is controlled.

Normally, in the USB interface, a single end zero (SE0) is set to an end of packet (EO).
P), reset, and detection of line disconnection. In the present embodiment, the device connected via the USB connector 30 and the cable 23 is a host or a peripheral device with respect to the own electronic device 20. It is also used to determine

Next, the connection operation of the electronic device 20 with another device via the interface circuit 19 in the present embodiment will be described. FIG. 4 is a flowchart showing an operation when data transfer is performed by the USB control unit 38 via the interface circuit 19.

The electronic device 20 includes an interface circuit 1
A cable 23 is connected to a USB connector 30 of the ninth, and a personal computer 24 is connected as a peripheral device 22 or a host.

First, when the electronic device 20 enters the USB data transfer mode, the USB control unit 38 of the interface circuit 19 determines whether the partner device connected via the cable 23 is the peripheral device 22 or the personal computer 24. In order to determine, the signals of PV +, PVG, PV- are turned off ("0") to disconnect all the connection resistances of the data lines D +, D- (step S1). The output (SE0 Detect signal) is determined (step S2).

When the connected device is the personal computer 24 serving as a host, pull-down resistors are connected to the data lines D + and D- in the interface circuit of the personal computer 24. Therefore, the state of the signal input through the terminals D + and D− of the USB connector 30 becomes low level “0”, and SE0 becomes “1”.

When SE0 is "1", the electronic device 20 becomes a peripheral device with respect to the personal computer 24 as the host. In this case, the USB control unit 38 of the interface circuit 19 turns on the PV + signal.
("1"), the switch SW1 is switched, and the pull-up resistor 44 is connected to the data line D + to set high-speed transfer, or the signal of PV- is turned on.
("1"), the switch SW3 is switched, and the pull-up resistor 48 is connected to the data line D- to set a state for low-speed transfer (step S3). Whether high-speed transfer or low-speed transfer is performed is determined by the characteristics of the system of the electronic device 20.

Therefore, when the electronic device 20 is a peripheral device and performs high-speed transfer, the switches SW1 to SW5 of the switching section 34 are switched as shown in "high-speed transfer (peripheral)" in FIG. SW1 is ON and switch S
W2 to SW5 are turned off. That is, only the pull-up resistor (R2) 44 is connected to the data line D +,
The terminal Vcc of the SB connector 30 and the terminal P2 of the power supply circuit 40 of the power supply unit 32 are connected via the diode 42. By connecting the terminal Vcc to the terminal P2 of the power supply circuit 40, power supplied from the host (personal computer 24) can be taken.

When the electronic device 20 is a peripheral device and performs low-speed transfer, the switches SW1 to SW5 of the switching unit 34 are switched as shown in "low-speed transfer (peripheral)" in FIG. SW3 is ON and switch SW
1, SW2, SW4 and SW5 are turned off. That is, only the pull-up resistor (R2) 48 is connected to the data line D-, and the terminal Vcc of the USB connector 30 and the terminal P2 of the power supply circuit 40 of the power supply unit 32 are connected via the diode 42. When performing low-speed transfer, the terminal Vc
By connecting the terminal c to the terminal P2 of the power supply circuit 40, the power supplied from the host (personal computer 24) is taken.

On the other hand, in step S2, SE0 "0"
Is determined, the connected partner device is the peripheral device 22. That is, when the partner device is the peripheral device 22, since the pull-up resistor is connected to one of the data lines D + and D− in the interface circuit on the peripheral device 22 side, the terminals D +,
One of the states of the signal input through D- becomes low level "0", the other becomes high level "1", and SE0 becomes "0".
Becomes

When SE0 is “0”, the electronic device 20 becomes a host for the peripheral device 22. In this case, the USB control unit 38 determines the transfer rate of the peripheral device 22 with reference to the Rcv Data signal from the differential receiver 52 of the USB transceiver unit 36 (Step S).
5). If the Rcv Data signal is "1", high-speed transfer,
If the Rcv Data signal is "0", low-speed transfer is performed.

The USB control unit 38 of the interface circuit 19 switches the switch SW2 and the switch SW4 by turning on the signal of the PVG (“1”) to perform the pull-down operation regardless of the high-speed transfer or the low-speed transfer. The resistances (R1) 46, 49 are connected to the data lines D +, D-, respectively, and set to a transfer state (steps S6, S
8).

Therefore, when the electronic device 20 functions as a host, the switches SW1 to S
W5 is a switch S as shown in "Host" in FIG.
W1 and SW3 are OFF and switches SW2 and SW
4, SW5 turns ON. That is, the data line D +
Is connected to a pull-down resistor (R1) 46, the data line D− is connected to a pull-down resistor (R1) 49, and US
Terminal Vcc of B connector 30 and power supply circuit 4 of power supply section 32
0 terminal P1 is connected via a diode 41.
By connecting the terminal Vcc to the terminal P1 of the power supply circuit 40, power can be supplied to the peripheral device 22.

Further, the USB control unit 38 sets the OE signal to “0” after turning the PVG signal ON (“1”), and sets the Xm
Transfer data by the t Data signal (step S7,
S9).

Thus, the pull-up resistor (R2)
44, 48, and pull-down resistors (R1) 46, 49, whether the electronic device 20 functions as a host or a peripheral device, and whether to perform high-speed transfer or low-speed transfer when functioning as a peripheral device. Is controlled so as to switch the connection to the data lines D + and D- in accordance with the condition (1), the interface circuit 19 provided with one USB connector 30 is used as a host when the electronic device 20 is used as a host and as a peripheral device. It can be used wherever it is used.

Depending on whether the electronic device 20 functions as a host or a peripheral device, the connection between the pull-up resistor and the pull-down resistor is switched, and
The power supply from the power supply unit 32 to the peripheral devices or the power supply from the host is also switched.

In the above embodiment, whether the connected device is a host or a peripheral device is determined based on the signal levels of the data lines D + and D-. Assuming that power is always supplied from the Vcc line, the host and the peripheral device may be determined by measuring the voltage when a constant load is applied to the Vcc line in FIG.

Specifically, if a constant load is applied to the Vcc line and the voltage does not decrease, power is supplied, and it can be determined that the connected device is the host. Further, when the voltage is reduced by applying a certain load to the Vcc line, power is not supplied, and it can be determined that the connected device is a peripheral device.

In this case, a resistance for applying a constant load to the Vcc line and a load due to this resistance are applied.
A circuit for detecting a voltage drop at this time is provided, and this circuit notifies the USB control unit 38 of the detection result, thereby determining whether the connected device is a host or a peripheral device. In response to this notification, the USB control unit 38 controls the switches of the switching unit 34 and controls the USB transceiver unit 36 in the same manner as described above.

[0066]

As described above in detail, according to the present invention, in an electronic device having an interface circuit for connecting another device, the interface circuit is a first device for connecting two data lines. A connector provided with a second terminal for connecting the terminal to the power supply line, a power supply for supplying power through a power supply line connected to the second terminal of the connector, and a first terminal of the connector Selectively connect a pull-up resistor and a pull-down resistor to each of the data lines connected to
A switching unit for switching the connection between the power supply unit and the second terminal of the connector; controlling the connection of the pull-up resistor and the pull-down resistor to the data line by the switching unit; and switching the connection between the power supply unit and the second terminal of the connector. When the connected device functions as a host, the pull-up resistor can be connected to the data line to transfer data as a peripheral device, and the connected device can be connected to the peripheral device. When used as a host, the data can be transferred as a host by connecting a pull-down resistor to the data line, so use the electronic device both as a host and as a peripheral device without providing two interfaces. Is possible.

[Brief description of the drawings]

FIG. 1 is an exemplary block diagram showing a schematic configuration of an electronic apparatus according to an embodiment of the invention.

FIG. 2 is a diagram showing an example of a connection configuration between a peripheral device 22 and another device via an interface circuit 19 in the embodiment.

FIG. 3 is a diagram showing a detailed configuration of an interface circuit 19;

FIG. 4 is an interface circuit 1 by a USB control unit 38;
9 is a flowchart showing an operation in the case of performing data transfer via the control unit 9.

FIG. 5 is a diagram for explaining a correspondence relationship between states of each switch in a switching unit.

FIG. 6 shows a host 80 using a conventional USB interface.
FIG. 4 is a diagram showing an example of a connection form between a device and a peripheral device 82;

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 ... CPU 12 ... Memory 14 ... External storage device 16 ... Display device 17 ... Input device 19 ... Interface circuit 20 ... Electronic equipment 22 ... Peripheral equipment 24 ... Personal computer 30 ... USB connector 32 ... Power supply part 34 ... Switching part 36 ... USB Transceiver 38 ... USB control unit 50 ... Differential driver 52 ... Differential receiver 54,56 ... Single-ended receiver

Claims (5)

[Claims] 1. An electronic device having an interface circuit for connecting another device, wherein the interface circuit includes a first terminal for connecting two data lines and a second terminal for connecting a power line. A connector provided with a terminal, a power supply means for supplying power through a power supply line connected to a second terminal of the connector, and a data line connected to a first terminal of the connector. Switching means for selectively connecting a pull-up resistor and a pull-down resistor, and switching the connection between the power supply means and the second terminal of the connector; and the data of the pull-up resistance and the pull-down resistance by the switching means. Control means for controlling connection to a line and switching of connection between the power supply means and a second terminal of the connector. Electronic equipment that characterized the door. 2. The apparatus according to claim 1, further comprising: a detecting unit configured to detect whether the connected device functions as a host or a peripheral device with respect to the own device. When the connected device functions as a host, the switching means connects the pull-up resistor to the data line. When the connected device functions as a peripheral device, the switching means connects the pull-down resistor to the data line. The electronic device according to claim 1, wherein: 3. The apparatus according to claim 1, wherein the detecting unit detects whether the connected device functions as a host or a peripheral device for the device based on a signal level of the data line. 2. The electronic device according to 2. 4. The detection means applies a resistance for applying a constant load to the power supply line, and a load by the resistance, and determines whether or not a connected device determines its own device based on the presence or absence of a voltage drop at this time. 3. The electronic device according to claim 2, further comprising a circuit for detecting whether the device functions as a host or a peripheral device. 5. An interface circuit for connecting another device, comprising: a connector provided with a first terminal for connecting two data lines and a second terminal for connecting a power supply line; Power supply means for supplying power through a power supply line connected to a first terminal of the connector; and a pull-up resistor and a pull-down resistor for each of the data lines connected to the first terminal of the connector. Switching means for selectively connecting the power supply means and the second terminal of the connector, a transceiver for transmitting or receiving data through the two data lines, and a pull by the switching means. Connection of an up resistor and a pull down resistor to the data line and disconnection of connection between the power supply means and a second terminal of the connector; Controls the example, interface circuit, characterized by comprising a control means for controlling the transmission and reception of data by the transceiver.