A high-speed serial communication circuit

Abstract

The application discloses a high-speed serial communication circuit, which comprises a transceiving host, a plurality of transceiving slaves, a first automatic direction control module, a second automatic direction control module and a plurality of competition suppression modules; the data sending port of the transceiving host is connected to the data receiving ports of all the transceiving slaves simultaneously, and the data sending port of the transceiving host is connected to the input port of the first automatic direction control module and then connected to the transceiving mode switching ports of all the transceiving slaves; the output port of the first automatic direction control module is connected to the transceiving mode switching ports of all the transceiving slaves simultaneously; the data sending port of each transceiving slave is connected to the input port of a competition suppression module; the output ports of all the competition suppression modules are connected to the second automatic direction control module and then connected to the transceiving mode switching port of the transceiving host; meanwhile, the output ports of all the competition suppression modules are directly connected to the data receiving port of the receiving host.

Description

Technical Field

[0001] This invention relates to the field of digital communication technology, and in particular to a high-speed serial communication circuit. Background Technology

[0002] In existing technologies, serial bus-based communication methods offer various device connection options, such as daisy-chain, star, and T-connection. The most common daisy-chain connection, if there are many nodes and the devices are powered via the same cable, requires thicker cables to ensure power and signal quality. This leads to complex installation and higher costs. Furthermore, in a daisy-chain connection, cables must connect from one node to the next. Due to the location of some devices (e.g., in different rooms), this requires long cables, increasing cable costs and complicating wiring. Moreover, in a daisy-chain configuration, each node operates on a one-to-many basis; the more nodes, the lower the stable communication speed. This solution is unsuitable for devices requiring high-speed communication. For example, the RS485 communication protocol supports a maximum of 32 nodes using a daisy-chain connection, which is insufficient for applications with more nodes. For star and T-connection methods, echo reflection can cause problems with communication signal quality.

[0003] It is evident that the existing technology lacks a circuit capable of achieving high-speed serial communication while overcoming the aforementioned technical difficulties, thereby realizing high-speed and stable signal communication in serial mode. Summary of the Invention

[0004] This invention provides a high-speed serial communication circuit, comprising a transceiver master, multiple transceiver slaves, a first automatic direction control module, a second automatic direction control module, and multiple contention suppression modules. The data transmission port of the transceiver master is simultaneously connected to the data reception ports of all transceiver slaves, and the data transmission port of the transceiver master is connected to the input port of the first automatic direction control module. The output port of the first automatic direction control module is simultaneously connected to the transmit / receive mode switching ports of all transceiver slaves. Each transceiver slave's data transmission port is connected to the input port of a contention suppression module. The output ports of all contention suppression modules are connected to the input port of the second automatic direction control module, and the output port of the second automatic direction control module is connected to the transmit / receive mode switching port of the transceiver master. Simultaneously, the outputs of all contention suppression modules are directly connected to the data reception port of the receiving master. In one embodiment, both the transceiver master and the transceiver slaves are provided with differential signal ports.

[0005] In one embodiment, both the first automatic direction control module and the second automatic direction control module include a transistor switching device, a first capacitor, and a grounding resistor.

[0006] In one embodiment, the transistor switching device uses a PNP transistor or a P-type MOS transistor.

[0007] In one embodiment, the contention suppression module includes a diode connected in reverse series on the data transmission port of the receiving slave device and a pull-up resistor set at the data receiving port of the receiving master device.

[0008] In one embodiment, the CT value of the diode is in the range of 5nF ​​to 15nF.

[0009] Compared with the prior art, one or more embodiments of the present invention may have the following advantages:

[0010] This invention effectively enables lossless transmission of the master signal to the slave by incorporating an automatic direction control module between the receiving master and the receiving slave, thereby improving the communication link speed to 1MB / s. Simultaneously, this invention effectively reduces contention for the communication line among multiple slaves by utilizing a contention suppression module at the slave output port.

[0011] Other features and advantages of the invention will be set forth in the description which follows, and will be apparent in part from the description, or may be learned by practicing the invention. The objects and other advantages of the invention may be realized and obtained by means of the structures particularly pointed out in the description, claims and figures. Attached Figure Description

[0012] The accompanying drawings are provided to further illustrate the invention and form part of the specification. They are used in conjunction with the embodiments of the invention to explain the invention and do not constitute a limitation thereof. In the drawings:

[0013] Figure 1 This is a schematic diagram of the structure of a high-speed serial communication circuit according to an embodiment of the present invention;

[0014] Figure 2 This is a circuit structure diagram of an automatic direction control module according to an embodiment of the present invention. Detailed Implementation

[0015] To make the objectives, technical solutions, and advantages of the present invention clearer, the present invention will be further described in detail below with reference to the accompanying drawings.

[0016] like Figure 1As shown, this embodiment uses a typical RS485 communication protocol as an example. Under the RS485 communication protocol, the high-speed serial communication circuit of the present invention includes: a transceiver master 1, multiple transceiver slaves 2, a first automatic direction control module 3, a second automatic direction control module 4, and multiple contention suppression modules 5. The data transmission port RO of the transceiver master 1 is simultaneously connected to the data reception ports DI of all transceiver slaves 2. The data transmission port RO of the transceiver master 1 is connected to the input port of the first automatic direction control module 3. The output port of the first automatic direction control module 3 is simultaneously connected to the transmit / receive mode switching ports RE / DE of all transceiver slaves 2. Each data transmission port RO of all transceiver slaves 2 is connected to a contention suppression module 5. The outputs of the multiple contention suppression modules 5 are connected to the input port of the second automatic direction control module 4. The output port of the second automatic direction control module 4 is connected to the transmit / receive mode switching port RE / DE of the transceiver master 1. The outputs of the multiple contention suppression modules 5 are also directly connected to the data reception port DI of the receiving master 1.

[0017] According to the RS485 communication protocol, both the transceiver master and slave in this embodiment are equipped with differential signal ports, namely ports A+ and B-, which are used to receive or transmit a pair of differential signals. Since the signals are differential and are bus-mounted, the communication mode is limited to half-duplex, meaning only one device can transmit data at a time. Therefore, strict direction control is required for signal transmission and reception; only one device can be in transmitting mode at a time, while other devices are in receiving mode to avoid data conflicts on the bus. This embodiment provides a signal replication circuit based on the RS485 communication protocol signal, capable of dividing a single set of RS485 communication protocol signals into multiple independent RS485 communication protocol signals and transmitting them to the transceiver slave. Direction control is automatically controlled by the differential signals, requiring no other peripheral equipment, resulting in lower implementation costs and easier maintenance.

[0018] In this embodiment, the receiving host and receiving slave can specifically use one of MAX483~491, MAX1487, MAX3080~3089, SN75276, SN75LBC184, or other models of RS485 communication chips.

[0019] When transceiver host 1 receives a signal, its data transmission port RO outputs a converted RS485 signal. This signal, after passing through the first automatic direction control module 1, controls the transmit / receive mode switching ports RE / DE of all transceiver slave devices 2 to be in transmit mode, and transmits the signal received by the transceiver host. In this way, the RS485 signal transmitted by transceiver host 1 is losslessly converted into multiple independent RS485 signals and transmitted from the transceiver slaves. This achieves the effect of signal enhancement and separation. Simultaneously, when any of the transceiver slave devices 2 receives an RS485 signal, it will also transmit the signal through the output of its data transmission port RO, via the second automatic direction control module 4, to switch the transmit / receive mode switching port RE / DE of transceiver host 1 to transmit mode, thus enabling the signal to be transmitted outward through the transceiver host.

[0020] In this embodiment, the transceiver master and transceiver slave, based on the RS485 communication protocol, are in receive mode by default during normal operation. They convert the signals from their differential signal input ports A+ and B- to TTL levels, which are then output from the data transmit port RO of the transceiver master or slave. The main function of the first and second automatic direction control modules in this embodiment is to control the transmit / receive mode switching port RE / DE to the output state when the transceiver master or slave needs to output. Only when the transmit / receive mode switching port RE / DE is in the output state can the transceiver master or slave convert the input level of the data receive port DI into a differential signal based on the RS485 communication protocol and output it from the differential signal port.

[0021] In this embodiment, the first automatic direction control module 3 and the second automatic direction control module 4 adopt the same circuit structure, such as Figure 2 As shown. Both the first automatic direction control module 3 and the second automatic direction control module 4 include a transistor switching device 11, a first capacitor 12, and a grounding resistor 13. The transistor switching device 11 uses a PNP high-speed transistor or a high-speed P-type MOSFET. The selection of the first capacitor 12 needs to be coordinated with the grounding resistor 13. By controlling the RC charging and discharging time, the rate of change of the output signal is controlled, thereby achieving the purpose of the automatic direction control circuit output signal being slightly slower than the input signal. This prevents the direction control signal from being faster than the input signal. When the TXD signal changes from 0 to 1, the automatic direction control chip changes from the output state to the input state. If the speed at which the direction control pin changes to the input state is faster than the pull-up speed of the AB differential bus, a falling edge glitch will be output on the data transmission port RO.

[0022] In this embodiment, when the transistor switching device 11 uses a PNP high-speed transistor, the first capacitor 12 is connected between the collector and emitter of the PNP high-speed transistor, and the collector of the PNP high-speed transistor is connected to the grounding capacitor 13 and grounded. The emitter of the PNP high-speed transistor is connected to a 5V power supply.

[0023] The automatic direction control circuit in this embodiment cleverly utilizes the TXD signals of the receiving master and receiving slave. When the data transmission port RO of the receiving master is high, the first automatic direction control module inputs a high level and outputs a low level, and the receiving slave becomes an input device. At this time, there is no level change on the AB differential bus, and due to the pull-up resistor on the A+ line and the pull-down resistor on the B- line, the level difference between the A+ and B- lines will be >0.2V, causing the RS485 bus output to be high, i.e., the AB bus output is 1. When the data transmission port RO of the receiving master is low, the first automatic direction control module outputs a high level, and the receiving slave 2 becomes an output device. The receiving slave 2 will output a low level onto the AB bus, pulling the AB differential bus low and controlling the level difference to <0.2V. At this time, the RS485 bus output is low, i.e., the AB differential bus output is 0.

[0024] In applications requiring numerous receiver slaves, when all the data transmission ports RO of receiver slaves 2 are connected together and then connected to the input of the second automatic direction control module, each receiver slave 2's data transmission port RO can theoretically control the output signal on that data line. This leads to signal contention. For example, if receiver slave U2 needs to pull the signal low, but other receiver slaves U3 through Un are all outputting high, receiver slave U2 cannot pull the signal low. Signal contention can cause signal errors, and in severe cases, can even cause useful signals to be overwhelmed by other signals.

[0025] In this embodiment, to avoid signal contention between the output signals of multiple slave receivers 2, a diode with a very small junction capacitance CT value (ranging from 5nF to 15nF) is connected in reverse series to the data transmission port RO of each slave receiver 2. The anode of the diode is connected to the input terminal of the second direction control module 4, and the cathode of the diode is connected to the data transmission port RO of the slave receiver 2. When the anodes of multiple diodes are connected together, the pull-up resistor at the data reception port DI of the master receiver can pull the output bus high. Thus, when any slave receiver 2 outputs a low level, the bus can be pulled low, and when it outputs a high level, the second resistor can automatically pull the bus high, thereby achieving the purpose of contention suppression.

[0026] The above description is merely a specific implementation example of the present invention, and the scope of protection of the present invention is not limited thereto. Any modifications or substitutions made to the present invention by those skilled in the art within the technical specifications described herein should be within the scope of protection of the present invention.

Claims

1. A high-speed serial communication circuit, characterized in that, The serial communication circuit includes a transceiver master, multiple transceiver slaves, a first automatic direction control module, a second automatic direction control module, and multiple contention suppression modules. The data transmission port of the transceiver master is simultaneously connected to the data reception ports of all transceiver slaves, and the data transmission port of the transceiver master is connected to the input port of the first automatic direction control module. The output port of the first automatic direction control module is simultaneously connected to the transmit / receive mode switching ports of all transceiver slaves. The data transmission port of each transceiver slave is connected to the input port of a contention suppression module. The output ports of all contention suppression modules are connected to the input port of the second automatic direction control module, and the output port of the second automatic direction control module is connected to the transmit / receive mode switching port of the transceiver master. Simultaneously, the outputs of all contention suppression modules are directly connected to the data reception ports of the transceiver master. Both the first automatic steering control module and the second automatic steering control module include transistor switching devices, a first capacitor, and a grounding resistor; the first automatic steering control module and the second automatic steering control module adopt the same circuit structure; the first capacitor, together with the grounding resistor, controls the RC charging and discharging time to control the rate of change of the output signal, so that the output signal of the automatic steering control circuit is slower than the input signal.

2. The serial communication circuit according to claim 1, characterized in that, Both the transceiver host and the transceiver slave are equipped with differential signal ports.

3. The serial communication circuit according to claim 1, characterized in that, The transistor switching device uses a PNP transistor or a P-type MOS transistor.

4. The serial communication circuit according to claim 1, characterized in that, The contention suppression module includes a diode connected in reverse series on the data transmission port of the transceiver slave and a pull-up resistor set at the data reception port of the transceiver master.

5. The serial communication circuit according to claim 4, characterized in that, The CT value of the diode is in the range of 5nF ​​to 15nF.

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