Low-delay synchronous forwarding system based on MCU

Abstract

The invention discloses a low-delay synchronous forwarding system based on an MCU (Microprogrammed Control Unit), which is applied to the field of communication, and aims to solve the problems that the system delay is increased due to a mode that the existing forwarding system based on the MCU firstly receives and then forwards, and the existing system does not consider the problem of forwarding signal synchronization, so that the forwarding signal cannot meet the protocol requirement required by the system due to low speed of a transmitting device. According to the invention, transmitting signal synchronization is carried out in the MCU based on the output clock of the transmitting device, so that the problem that a system forwarding signal is not synchronous with a base station or the transmitting device is solved, and the problem that the forwarding signal cannot meet the protocol requirement required by the system due to low speed of the transmitting device is avoided.

Description

Technical Field

[0001] The invention belongs to the field of signal processing and system control, and in particular relates to a forwarding system based on MCU. Background Art

[0002] As we all know, in order to reduce system cost, power consumption and design complexity, most systems use MCU (microprogrammed control unit) to implement signal processing and system control functions. However, the system based on MCU has low speed and cannot realize signal synchronization function, which limits its application scenarios. If the system needs to meet the specified protocol timing, especially the high-speed / parallel system, most of them are implemented by FPGA (field programmable gata array). However, FPGA has high power consumption, high cost and high design complexity, and it is difficult to use it in low-power, low-cost and passive fields. These fields are mostly implemented by MCU, and their system timing is very difficult. At the same time, in the application scenario where the repeater is required to improve the coverage of the system, the delay is further added, which causes the system to fail to work properly, or requires more expensive components and complex design methods to meet the system timing requirements, which further increases the system cost, power consumption and design complexity. Therefore, there is an urgent need for a low-power, low-cost method to solve the delay and synchronization problems in the repeater.

[0003] The existing MCU-based forwarding system design method is that the forwarder first receives the data transmitted by the base station, then re-encodes the data according to the protocol standard required by the system, and finally forwards it through the transmitting circuit.

[0004] The disadvantages of the prior art are: the mode of receiving first and then forwarding in the prior art increases the system delay. At the same time, the prior system does not consider the problem of forwarding signal synchronization. There is a problem that the forwarding signal cannot meet the protocol requirements of the system due to the low rate of the transmitting device. Summary of the invention

[0005] In order to solve the above technical problems, the present invention proposes a low-latency synchronous forwarding system based on MCU, which does not need to receive data and directly forwards signals, thereby reducing system latency. In the MCU, transmission signal synchronization is performed based on the output clock of the transmitting device, eliminating the problem of the system forwarding signal being out of synchronization with the base station or the transmitting device, and avoiding the problem of the forwarding signal being unable to meet the protocol requirements of the system due to the low rate of the transmitting device.

[0006] The technical solution adopted by the present invention is: a low-latency synchronous forwarding system based on MCU, comprising: a receiving antenna, a transmitting antenna, a receiving link, a transmitting link, a power module, and an MCU; the power module supplies power to the receiving link, the transmitting link, and the MCU;

[0007] The receiving link demodulates the RF signal received by the receiving antenna, and the obtained demodulated signal is input into the MCU; the MCU synchronously forwards the demodulated signal with low latency, and the forwarded signal is modulated by the transmitting link and transmitted by the transmitting antenna;

[0008] It also includes: a system control module, a low-latency forwarding module, and a synchronous forwarding module implemented based on an MCU; the system control module is connected to a receiving link and a transmitting link respectively through SPI, and the system control module is used to generate true random numbers; the MCU selects a low-latency forwarding module or a synchronous forwarding module to work; the low-latency forwarding module and the synchronous forwarding module output a modulated signal based on the demodulated signal under the control of the system control module;

[0009] The low-latency forwarding module is set to double-edge trigger of the demodulation signal. When the MCU detects that the demodulation signal is a falling edge, the forwarding signal is set to low; when the MCU detects that the demodulation signal is a rising edge, the forwarding signal is set to high.

[0010] The synchronous forwarding module is set to be triggered by the falling edge of the demodulated signal and the falling edge of the output clock signal of the transmitting device; after the MCU detects the falling edge of the demodulated signal, it continues to detect the falling edge of the clock signal, and sets the forwarding signal to low; then it continues to detect the falling edge of the clock signal and sets the forwarding signal to high;

[0011] The transmitting link encodes the input modulated signal and transmits it through the transmitting antenna.

[0012] Beneficial effects of the invention: The invention proposes a low-latency synchronous forwarding system based on MCU, which can realize the RF signal forwarding function, and at the same time adopts MCU to realize low-latency signal forwarding, and can realize signal synchronous forwarding, and can realize parallel receiving and sending functions similar to FPGA. At the same time, it does not affect the networking function with the base station, and greatly reduces the cost, power consumption and design complexity of the forwarding system. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] Figure 1 It is a low-latency synchronous forwarding system architecture based on MCU;

[0014] Figure 2 For low-latency forwarding module workflow;

[0015] Figure 3 The working timing of the low-latency forwarding module;

[0016] Figure 4 For low-latency forwarding module workflow;

[0017] Figure 5 It is the working timing of the synchronous forwarding module. DETAILED DESCRIPTION

[0018] To facilitate those skilled in the art to understand the technical content of the present invention, the present invention is further explained below with reference to the accompanying drawings.

[0019] The low-latency synchronous forwarding system architecture based on MCU proposed in the present invention is as follows: Figure 1 As shown, it includes transceiver antennas, receiving links, transmitting links, power modules, MCU, etc., wherein MCU realizes system control module, low-latency forwarding module, synchronous forwarding module, etc., and can realize networking function with base station (control center). In the figure, f1 and f2 represent receiving and transmitting frequencies respectively, and BPF1 and BPF2 are filters of corresponding frequencies.

[0020] The system control module controls the ADC sampling time, implements signal processing, generates the final true random number, implements data transmission and reception, etc.

[0021] The MCU controls the working status of the receiving device of the receiving link and the transmitting device of the transmitting link through the SPI bus. The receiving device demodulates the received RF signal and outputs a digital signal, i.e., a demodulated signal. The MCU selects a low-latency forwarding module or a synchronous forwarding module to work; the low-latency forwarding module determines the status of the received signal and outputs a modulated signal, and the synchronous forwarding module outputs a modulated signal, i.e., a forwarding signal, under the control of the output clock signal of the transmitting device.

[0022] A) Low-latency forwarding module

[0023] The low-latency forwarding module workflow is as follows: Figure 2 As shown, the MCU sets the demodulation signal pin to double-edge trigger (both rising and falling edges are triggered). If the MCU detects that the demodulation signal is a falling edge, the forwarding signal is set to low; if the MCU detects that the demodulation signal is a rising edge, the forwarding signal is set to high; if the start of networking is detected, the low-latency forwarding module continues to execute, and if the end of networking is detected, the low-latency forwarding module ends its work.

[0024] The working sequence of the low-latency forwarding module is as follows: Figure 3 As shown, the transmission signal is the modulated signal output by forwarding, RT cal is the judgment symbol of whether the coded data is 0 or 1, data0 and data1 are the symbols of coded data 0 and 1 respectively, RT cal The symbol length of data1 is longer than that of data0, and the symbol length of data1 is longer than that of data0. Figure 3 It can be seen that the maximum delay of the low-latency forwarding module is only one transmitting device output clock cycle, but the forwarded symbols are of different lengths, which can easily lead to subsequent decoding errors. In particular, the high-level duty cycle of data0 is too small, about 30%, which can easily cause the passive tag (RFID application scenario) to lose power, making the tag unable to work normally.

[0025] In the UHF RFID application scenario, the decoding of data0 and data1 is determined by the following formula:

[0026]

[0027] Among them, RT cal It is used to represent the length of data0 and data1 symbols. Formula (1) can be understood as: when the length of the data symbol in the signal forwarded by the transponder received by the tag is greater than RT cal / 2, it means that the symbol is data 1 (data1); when the length of the data symbol in the forwarded signal received by the label is less than RT cal / 2, it means that the symbol is data 0 (data0).

[0028] Therefore, by Figure 3 It can be seen from the timing that in order to meet the timing requirements of the UHF RFID system, the RT in the forwarding output signal cal The following inequality requirements should be met:

[0029]

[0030] Among them, T clk is the output clock period of the transmitting device, and after simplification, we can get:

[0031] 2data0+3T clk <RT cal <2data1-3T clk (3)

[0032] When RT cal If formula (3) is satisfied, the forwarded signal will not cause decoding errors in the passive tag, and a one-clock-cycle delay function can be achieved, which is equivalent to using FPGA or dedicated chips, reducing the system delay of the traditional MCU forwarding method, and with lower power consumption and cost.

[0033] B) Synchronous forwarding module

[0034] The synchronous forwarding module workflow is as follows: Figure 4 As shown, the MCU sets the demodulation signal falling edge trigger and the clock signal falling edge trigger. After the MCU detects that the demodulation signal is a falling edge, it continues to detect the falling edge of the clock signal, and sets the forwarding signal to low; then it continues to detect the falling edge of the clock signal and sets the forwarding signal to high; if it is detected that the networking starts, the synchronous forwarding module continues to execute, and if it is detected that the networking ends, the synchronous forwarding module ends its work.

[0035] The working sequence of the synchronous forwarding module is as follows: Figure 5 As shown, from Figure 5It can be seen that the maximum delay of the synchronous forwarding module is 2 clock cycles (for example, when the clock rising edge changes, it will be delayed by 2 clock cycles), but the low level of the forwarding symbol is fixed to one clock cycle, and the high level duty cycle of data0 will not be less than 50% and will not be greater than 75%, which is moderate. At the same time, it will not cause the passive tag (RFID application scenario) to lose power, thereby improving the system reliability.

[0036] Therefore, by Figure 5 It can be seen from the timing that in order to meet the timing requirements of the UHF RFID system, the RT in the forwarding output signal cal The following inequality requirements should be met:

[0037]

[0038] Among them, T clk is the output clock period of the transmitting device, and after simplification, we can get:

[0039] 2data0+6T clk <RT cal <2data1-6T clk (5)

[0040] When RT cal If formula (5) is satisfied, the forwarded signal will not cause decoding errors of the passive tag, and the 2 clock cycle delay and synchronization functions can be realized at the same time, which is equivalent to the use of FPGA or dedicated chip, and has lower power consumption and cost. Furthermore, the system delay of the traditional MCU forwarding method is reduced, and the synchronization function that cannot be achieved by the traditional MCU forwarding method is realized.

[0041] In actual applications, according to the specific application scenario, a low-latency forwarding module or a synchronous forwarding module is selected to work; for example, if an application scenario requires fast forwarding and the data rate is relatively low, synchronous forwarding is not required. The host computer sends a low-latency selection command, and the MCU uses the low-latency forwarding function; if a scenario requires a high data rate, if low-latency forwarding is used, the forwarding may be inaccurate, and synchronous forwarding is required. The host computer sends a synchronous forwarding command, and the MCU receives this command and uses the synchronous forwarding function.

[0042] In the art, it is generally believed that a data rate greater than or equal to 80 kbps is considered to be a relatively high data rate; otherwise, the data rate is relatively low.

[0043] Those skilled in the art will appreciate that the embodiments described herein are intended to help readers understand the principles of the present invention, and should be understood that the scope of protection of the present invention is not limited to such specific statements and embodiments. For those skilled in the art, the present invention may have various changes and variations. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of the claims of the present invention.

Claims

1. A low-latency synchronous forwarding system based on MCU, characterized in that: include: Receiving antenna, transmitting antenna, receiving link, transmitting link, power module, MCU; The power module supplies power to the receiving link, the transmitting link and the MCU; The receiving link demodulates the RF signal received by the receiving antenna, and the obtained demodulated signal is input into the MCU; The MCU forwards the demodulated signal synchronously with low latency. The forwarded signal is modulated by the transmission link and then transmitted by the transmitting antenna. It also includes: system control module, low-latency forwarding module and synchronous forwarding module based on MCU; The system control module is connected to the receiving link and the transmitting link through SPI respectively, and the system control module is used to generate true random numbers; the MCU selects the low-latency forwarding module or the synchronous forwarding module to work; the low-latency forwarding module and the synchronous forwarding module output the modulated signal based on the demodulated signal under the control of the system control module; The low-latency forwarding module is set to double-edge trigger of the demodulation signal. When the MCU detects that the demodulation signal is a falling edge, the forwarding signal is set to low; when the MCU detects that the demodulation signal is a rising edge, the forwarding signal is set to high. The synchronous forwarding module is set to be triggered by the falling edge of the demodulated signal and the falling edge of the output clock signal of the transmitting device; after the MCU detects the falling edge of the demodulated signal, it continues to detect the falling edge of the clock signal, and sets the forwarding signal to low; then it continues to detect the falling edge of the clock signal and sets the forwarding signal to high; The transmitting link encodes the input modulated signal and transmits it through the transmitting antenna.

2. According to claim 1, a low-latency synchronous forwarding system based on MCU is characterized in that: The receiving chain includes a first bandpass filter, a low-noise amplifier, and a receiving device; the RF signal input by the receiving antenna is filtered by the first bandpass filter, and the signal amplified by the low-noise amplifier enters the receiving device, and the receiving device is aligned for demodulation and outputs a demodulated signal.

3. The low-latency synchronous forwarding system based on MCU according to claim 2, characterized in that: The transmission link includes a second bandpass filter, a power amplifier, and a transmitting device; the transmission signal obtained by encoding the forwarded signal through the transmitting device is amplified by the power amplifier, filtered by the second bandpass filter, and finally transmitted through the transmitting antenna.

4. The low-latency synchronous forwarding system based on MCU according to claim 3 is characterized in that: A judgment symbol is set in the modulated signal, the symbol length of data 0 is smaller than the judgment symbol length, and the symbol length of data 1 is larger than the judgment symbol length.

5. The low-latency synchronous forwarding system based on MCU according to claim 4 is characterized in that: The symbol length in the modulated signal output by the low-latency forwarding module is judged to meet the following inequality requirements: Among them, T clk It is the clock cycle output by the transmitting device. data1 indicates the symbol length of data 1, and data0 indicates the symbol length of data 0.

6. The low-latency synchronous forwarding system based on MCU according to claim 5, characterized in that: The symbol length in the modulated signal output by the synchronous forwarding module satisfies the following inequality requirements:

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