ATmega128 16-channel remote control unit circuit analysis

This article introduces an ARTU-J16 with 16 remote control contact outputs. The device is connected to the host computer through the RS485 bus and serves as a remote relay output module. It is used to receive computer instructions and perform remote operation or automatic control of the system. The relay outputs are 16 in total. channel, the device has 1600 sets of operation event records, with GPS time correction function. It can ensure that the SOE event records will not be lost within a month after the external power supply is powered off. Compared with the previous control method, this design simplifies the control network structure and provides A low-cost, high-reliability alternative.

Main control CPU

The ARTU-J16 type 16-channel remote control execution unit is designed using ATMEL's ATmega128. A single chip realizes dual-channel RS485 communication, data processing, event record access, display and output status control of 16-channel relay normally open contacts. ATmega128 is an 8-bit RISC structure high-speed and low-power microcontroller launched by ATMEL. The system performance can reach 16MIPS at 16M clock frequency. It has 128k FlashROM, 4k EEPROM and 4k system SRAM; it can expand 64k external memory; two Road UART communication port. At the same time, the chip has a JTAG online programming port, which facilitates user debugging and reduces development costs. The 53 programmable I/O ports can connect enough peripheral devices.

DIP switch setting input

The DIP switch provides users with a simplified human-machine interface for setting the address, baud rate, data format and other setting functions in RS485 communication. The 10-bit data port of the DIP switch (SW1) is connected to a 10k resistor pull-up To Vcc, the circuit uses a 74HC244 (IC5) data buffer to transmit the status of the DIP switch to the 8-bit data bus, and the remaining two data lines are directly connected to the I/O port of the CPU (see Figure 2).

communication method

The communication method adopts dual-channel RS485 mode. The debugging and setting and host computer communication parts are physically divided into two channels without interfering with each other, effectively preventing possible misoperation (see Figure 3).