CN107766265B - Serial port data extraction method supporting fixed-length packets, variable-length packets and mixed packets - Google Patents
Serial port data extraction method supporting fixed-length packets, variable-length packets and mixed packets Download PDFInfo
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- CN107766265B CN107766265B CN201710796835.6A CN201710796835A CN107766265B CN 107766265 B CN107766265 B CN 107766265B CN 201710796835 A CN201710796835 A CN 201710796835A CN 107766265 B CN107766265 B CN 107766265B
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- G06—COMPUTING; CALCULATING OR COUNTING
- G06F—ELECTRIC DIGITAL DATA PROCESSING
- G06F13/00—Interconnection of, or transfer of information or other signals between, memories, input/output devices or central processing units
- G06F13/10—Program control for peripheral devices
- G06F13/12—Program control for peripheral devices using hardware independent of the central processor, e.g. channel or peripheral processor
- G06F13/124—Program control for peripheral devices using hardware independent of the central processor, e.g. channel or peripheral processor where hardware is a sequential transfer control unit, e.g. microprocessor, peripheral processor or state-machine
- G06F13/126—Program control for peripheral devices using hardware independent of the central processor, e.g. channel or peripheral processor where hardware is a sequential transfer control unit, e.g. microprocessor, peripheral processor or state-machine and has means for transferring I/O instructions and statuses between control unit and main processor
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- G—PHYSICS
- G06—COMPUTING; CALCULATING OR COUNTING
- G06F—ELECTRIC DIGITAL DATA PROCESSING
- G06F13/00—Interconnection of, or transfer of information or other signals between, memories, input/output devices or central processing units
- G06F13/38—Information transfer, e.g. on bus
- G06F13/382—Information transfer, e.g. on bus using universal interface adapter
- G06F13/387—Information transfer, e.g. on bus using universal interface adapter for adaptation of different data processing systems to different peripheral devices, e.g. protocol converters for incompatible systems, open system
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- G06—COMPUTING; CALCULATING OR COUNTING
- G06F—ELECTRIC DIGITAL DATA PROCESSING
- G06F13/00—Interconnection of, or transfer of information or other signals between, memories, input/output devices or central processing units
- G06F13/38—Information transfer, e.g. on bus
- G06F13/42—Bus transfer protocol, e.g. handshake; Synchronisation
- G06F13/4282—Bus transfer protocol, e.g. handshake; Synchronisation on a serial bus, e.g. I2C bus, SPI bus
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Abstract
The invention relates to a general method for extracting a serial port data packet, which supports three frame formats of a fixed length packet, a variable length packet and a mixed packet. The scheme used by the invention is as follows: and detecting whether the transmission of the serial port data packet is finished or not based on an idle trigger mechanism, and extracting the required serial port data packet from the received serial port data according to a configured packet format when the transmission is judged to be finished.
Description
Technical Field
The invention belongs to the field of embedded system serial port data processing, and relates to a serial port data extraction method supporting fixed-length packets, variable-length packets and mixed packets.
Background
In embedded applications, data interaction between devices is often performed in the form of serial data packets. Generally, a receiving party receives a serial port data packet in the following two ways: the CPU of the embedded system integrates a serial port controller with an idle interrupt characteristic, when the transmission of a data packet is finished, the interrupt is triggered, and an interrupt service program reads data in the controller; the embedded system integrates a single serial port coprocessor which can be in the forms of FPGA, SOC, special IC and the like, the package format is set through software, the coprocessor automatically processes serial port data and transmits the data conforming to the package format to a CPU for further processing.
The two data packet receiving modes have special requirements on hardware, so that the material cost is increased, and other influences such as power consumption and the like are brought to later-stage application. The invention completes the data packet receiving through software, and the software dynamically configures the packet format to complete the rapid deployment of the system.
Disclosure of Invention
The invention aims to provide a method for extracting a serial port data packet, which finishes the receiving of the serial port data packet through the dynamic configuration of software, and the packet format supports a fixed-length packet, a variable-length packet and a mixed packet.
The technical scheme of the invention is as follows: a serial port data extraction method supporting fixed-length packets, variable-length packets and mixed packets comprises the following steps:
step 1, initial configuration;
step 2, checking port numbers: when the input port number is in the system serial port list, continuing the subsequent operation; otherwise, returning an abnormal code;
step 3, serial port data overflow: when the system cannot process the data in the FIFO of the serial port controller in time, the data overflow occurs, FIFO data clearing operation is executed, and overflow flag words in the serial port controller are cleared;
step 4, judging whether the data count in the FIFO changes, if the count value is increased, backing up the count value, counting and resetting the counter; otherwise, the counter is accumulated by 1;
step 5, judging whether to be idle triggered: the timer is overtime, and the data count of the FIFO is greater than 0; if the conditions are met, the data transmission is judged to be finished, the data in the FIFO is in a state of being capable of being extracted and further processed, and the internal interruption of the CPU is triggered; if the timer is overtime but the FIFO count value is 0, setting the value of the timer as 'threshold value + 1';
and 6, resetting the timer, and finishing the data packet extraction according to the set packet format.
The method for extracting the serial port data supporting the fixed-length packet, the variable-length packet and the mixed packet comprises the following steps in the step 1:
step 1.1, configuring a packet format and a serial port channel number, wherein the packet format comprises a fixed-length packet, a variable-length packet and a mixed packet;
step 1.2, configuring the length of a packet head, the length of a packet tail and the total length;
step 1.3, configuring the header characters, the tail characters and the overtime threshold.
The method for extracting serial port data supporting fixed-length packets, variable-length packets and mixed packets comprises the following specific steps, when the packet format in step 6 is the fixed-length packet, step 6 specifically comprises the following steps:
6.1a, reading all data in the FIFO of the serial port controller to a software buffer area;
6.2a according to the set packet header, searching the packet header in the software buffer area, when the packet header is searched, returning the software buffer area index of the first packet header, and executing the step 3; if the packet header is not found, returning an abnormal code;
6.3a, judging the data length conformity, if the data length in the software buffer area is less than the packet length, returning an abnormal code; and if the data length in the software buffer area meets the condition, sequentially reading the data in the software buffer area according to the specified length, and returning the actually read data length and the data packet.
The method for extracting serial port data supporting fixed-length packets, variable-length packets and mixed packets comprises the following specific steps in step 6 when the packet format is the variable-length packet:
6.1b, reading all data in the FIFO of the serial port controller to a software buffer area;
6.2b according to the set packet header, searching the packet header in the software buffer area, when the packet header is searched, returning the software buffer area index of the first packet header, and executing the step 3; if the packet header is not found, returning an abnormal code;
6.3b, searching the packet tail backwards from the position of the packet head in the software buffer area according to the set packet tail, returning the software buffer area index of the first packet tail when the packet tail is searched, and executing the step 4; if the packet tail is not found, returning an abnormal code;
6.4b read all data between the header and the trailer in the software buffer, and return the actual length and all data read.
The serial port data extraction method supporting the fixed-length packet, the variable-length packet and the mixed packet comprises the following steps, in step 6, the packet format is the mixed packet, the mixed packet is composed of a plurality of variable-length packets, and the step 6 specifically comprises the following steps:
6.1c, reading all data in the FIFO of the serial port controller to a software buffer area;
and 6.2c, sequentially extracting the variable length packets from the software buffer according to the defined variable length packet sequence and the data extraction steps of the variable length packets, generating corresponding variable length packet updating marks, and setting the variable length packet updating marks if a certain variable length packet is extracted.
The invention has the beneficial effects that: the invention provides a serial port data packet receiving scheme with the characteristics of high real-time performance, strong universality, outstanding flexibility and the like for embedded system design, can be applied to occasions with variable external cross-linked data protocols, and completes serial port receiving reconstruction through dynamic configuration. Meanwhile, the hardware cost is reduced, and the overall power consumption of the embedded system can also be reduced.
Drawings
FIG. 1 "Idle trigger" process flow;
FIG. 2 is a main flow of data reception;
FIG. 3 is a fixed length packet data reception flow;
FIG. 4 is a variable length packet data receiving flow;
fig. 5 shows a flow of hybrid packet data reception.
Detailed Description
The invention has the following constraints on the packet format of the serial port controller and the communication:
1) the "idle trigger" mechanism: and setting a threshold of idle time as Ts, and after serial port data is detected, if new data is not received within the Ts time of the data bus, judging that one-time data packet transmission is finished and triggering internal interruption of the CPU. And after idle triggering, reading the data in the serial port FIFO by the interrupt service program, finishing the extraction of a data packet (any one of a fixed-length packet, a variable-length packet and a mixed packet) according to a configured packet format, returning the extracted data if the extraction is successful, and otherwise returning an abnormal code.
2) A fixed-length bag: the data frame is composed of a frame header of fixed length and data of fixed length.
3) A variable-length bag: the data frame is fully proved by a frame head with fixed length, a frame tail with fixed length and data, and the data length between the frame head and the frame tail is variable.
4) Mixing and packaging: the updating period of the variable-length packets can be different. The length of the hybrid package is not fixed.
5) And (3) fixing the length of the packet, setting the packet format to be a fixed-length packet during initialization, and setting according to the actual length.
6) And (3) changing the length of the packet, setting the format of the packet into a variable length packet during initialization, and setting the lengths of the packet head and the packet tail according to the actual length, wherein the sum of the lengths of the packet head and the packet tail is used as the minimum packet length.
7) And (3) setting the packet header of the fixed-length packet, setting the packet format as the fixed-length packet during initialization, and setting the length of the packet header and the characters of each byte of the packet header.
8) And (3) changing the packet header, setting the packet format into a changed-length packet during initialization, and setting the length of the packet header and the character of each byte of the packet header.
9) And (3) changing the packet tail of the variable-length packet, setting the packet format into the variable-length packet during initialization, and setting the length of the packet tail and the character of each byte of the packet tail.
10) Software buffer area: the minimum length of a section of space opened in the RAM is consistent with the size of the FIFO of the serial port controller.
11) Hardware requirements: the embedded system of the integrated serial port controller, the serial port controller contains receiving FIFO of certain size, the system adopts the regular inquiry way to gather the serial port data, the inquiry cycle is Ts.
12) Packet 1, the first variable length packet in the hybrid packet sequence set at initialization.
13) And a data packet N, the last variable-length packet in the set mixed packet sequence during initialization.
The invention is described in detail below with reference to the drawings of the specification, and the main flow of idle triggering is shown in fig. 1 and fig. 2.
1. Initial configuration:
1.1 configuration packet format (fixed length packet, variable length packet, mixed packet) and serial port channel number.
1.2 configuring the length of the header, the length of the tail and the total length (including the header and the tail).
1.3 configuring header characters, tail characters and overtime threshold.
2. Checking a port number: when the input port number is in the system serial port list, continuing the subsequent operation; otherwise, an exception code is returned.
3. And (3) serial port data overflow: when the system can not process the data in the FIFO of the serial port controller in time, the data overflow can occur, the FIFO data clearing operation is executed, and the overflow flag word in the serial port controller is cleared.
4. Judging whether the data count in the FIFO changes, if the count value is increased, backing up the count value, counting and resetting the counter; otherwise the counter is incremented by 1.
5. Judging whether to be idle triggered: the timer times out and the data count of the FIFO is greater than 0. If the conditions are met, judging that the data transmission is finished, extracting the data in the FIFO for further processing, and triggering the internal interruption of the CPU; if the timer times out, but the FIFO count value is 0, the value of the timer is set to "threshold + 1".
6. The timer is reset, and data packet extraction is completed according to the following steps according to the set packet formats (fixed length packet, variable length packet and mixed packet).
Extracting fixed length bag, as shown in figure 3:
6.1a reading all data in the serial port controller FIFO to the software buffer area.
6.2a, searching the packet header in the software buffer area according to the set packet header, returning the software buffer area index of the first packet header when the packet header is searched, and executing the step 6.3 a; if the packet header is not found, returning an abnormal code.
6.3a, judging the data length conformity, if the data length in the software buffer area is less than the packet length, returning an abnormal code; and if the data length in the software buffer area meets the condition, sequentially reading the data in the software buffer area according to the specified length, and returning the actually read data length and the data packet.
Variable length packet extraction, see figure 4:
6.1b, reading all data in the serial port controller FIFO to a software buffer area.
6.2b, searching the packet header in the software buffer area according to the set packet header, returning the software buffer area index of the first packet header when the packet header is searched, and executing the step 6.3 b; if the packet header is not found, returning an abnormal code.
6.3b, searching the packet tail backwards from the position of the packet head in the software buffer area according to the set packet tail, returning the software buffer area index of the first packet tail when the packet tail is searched, and executing the step 6.4 b; and if the packet tail is not found, returning an exception code.
6.4b read all data between the header and the trailer in the software buffer, and return the actual length and all data read.
Mixed package extraction, see figure 5:
6.1c, reading all data in the serial port controller FIFO to a software buffer area.
And 6.2c, sequentially extracting the variable-length packets from the defined variable-length packet sequence (the data packets 1 to N) in the software buffer according to the data extraction mode of the variable-length packets, generating corresponding variable-length packet updating marks, and setting the variable-length packet updating marks if a certain variable-length packet is extracted.
Claims (5)
1. A serial port data extraction method supporting fixed-length packets, variable-length packets and mixed packets is characterized by comprising the following steps:
step 1, initial configuration;
step 2, checking port numbers: when the input port number is in the system serial port list, continuing the subsequent operation; otherwise, returning an abnormal code;
step 3, serial port data overflow: when the system cannot process the data in the FIFO of the serial port controller in time, the data overflow occurs, FIFO data clearing operation is executed, and overflow flag words in the serial port controller are cleared;
step 4, judging whether the data count in the FIFO changes, if the count value is increased, backing up the count value, counting and resetting the counter; otherwise, the counter is accumulated by 1;
step 5, judging whether to be idle triggered: the timer is overtime, and the data count of the FIFO is greater than 0; if the conditions are met, the data transmission is judged to be finished, the data in the FIFO is in a state of being capable of being extracted and further processed, and the internal interruption of the CPU is triggered; if the timer is overtime but the FIFO count value is 0, setting the value of the timer as 'threshold value + 1';
and 6, resetting the timer, and finishing the data packet extraction according to the set packet format.
2. The method for extracting serial port data supporting fixed-length packets, variable-length packets and mixed packets according to claim 1, wherein the step 1 comprises the following steps:
step 1.1, configuring a packet format and a serial port channel number, wherein the packet format comprises a fixed-length packet, a variable-length packet and a mixed packet;
step 1.2, configuring the length of a packet head, the length of a packet tail and the total length;
step 1.3, configuring the header characters, the tail characters and the overtime threshold.
3. The method for extracting serial port data supporting fixed-length packets, variable-length packets and mixed packets according to claim 2, wherein when the packet format in step 6 is the fixed-length packet, step 6 specifically includes the following steps:
6.1a, reading all data in the FIFO of the serial port controller to a software buffer area;
6.2a according to the set packet header, searching the packet header in the software buffer area, when the packet header is searched, returning the software buffer area index of the first packet header, and executing the step 3; if the packet header is not found, returning an abnormal code;
6.3a, judging the data length conformity, if the data length in the software buffer area is less than the packet length, returning an abnormal code; and if the data length in the software buffer area meets the condition, sequentially reading the data in the software buffer area according to the specified length, and returning the actually read data length and the data packet.
4. The method for extracting serial port data supporting fixed-length packets, variable-length packets and mixed packets according to claim 2, wherein when the packet format in step 6 is a variable-length packet, step 6 specifically includes the following steps:
6.1b, reading all data in the FIFO of the serial port controller to a software buffer area;
6.2b according to the set packet header, searching the packet header in the software buffer area, when the packet header is searched, returning the software buffer area index of the first packet header, and executing the step 3; if the packet header is not found, returning an abnormal code;
6.3b, searching the packet tail backwards from the position of the packet head in the software buffer area according to the set packet tail, returning the software buffer area index of the first packet tail when the packet tail is searched, and executing the step 4; if the packet tail is not found, returning an abnormal code;
6.4b read all data between the header and the trailer in the software buffer, and return the actual length and all data read.
5. The method for extracting serial port data supporting fixed-length packets, variable-length packets and mixed packets according to claim 2, wherein the packet format in step 6 is a mixed packet, the mixed packet is composed of a plurality of variable-length packets, and step 6 specifically includes the following steps:
6.1c, reading all data in the FIFO of the serial port controller to a software buffer area;
6.2c, according to the defined variable length packet sequence, sequentially extracting the variable length packets from the software buffer according to the following data extraction steps of the variable length packets, generating corresponding variable length packet updating marks, and if a certain variable length packet is extracted, setting the variable length packet updating mark;
6.1b, reading all data in the FIFO of the serial port controller to a software buffer area;
6.2b according to the set packet header, searching the packet header in the software buffer area, when the packet header is searched, returning the software buffer area index of the first packet header, and executing the step 3; if the packet header is not found, returning an abnormal code;
6.3b, searching the packet tail backwards from the position of the packet head in the software buffer area according to the set packet tail, returning the software buffer area index of the first packet tail when the packet tail is searched, and executing the step 4; if the packet tail is not found, returning an abnormal code;
6.4b read all data between the header and the trailer in the software buffer, and return the actual length and all data read.
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| CN114301992A (en) * | 2021-12-29 | 2022-04-08 | 北京半导体专用设备研究所（中国电子科技集团公司第四十五研究所） | Data transmission method and storage medium |
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