49 lines
1.2 KiB
Markdown
49 lines
1.2 KiB
Markdown
# CH32-16-CH-EXT
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A simple CH32V003-based extension board providing 16 outputs (2x 74HC595), primarily designed for controlling [Chinese 16-relay modules](https://www.uctronics.com/download/Amazon/U604302_print.pdf) ([archive](https://web.archive.org/web/20220709045418/https://www.uctronics.com/download/Amazon/U604302_print.pdf)) over RS485. Uses 64-byte internal flash page for state persistence.
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KiCad hardware design files are in the `hw` directory.
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## comm protocol
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uses Modbus RTU protocol over RS485
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### Config
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```
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Baud Rate: 9600
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Data Bits: 8
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Stop Bits: 1
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Parity: None
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```
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### Modbus
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- Function Code: 0x06 (Write Single Register)
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- Default Slave Address: 0x01
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- Register Map:
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- Register 0x0000: Output Control Register (16 bits for controlling 16 relays)
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### Outputs
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Each bit in the control register corresponds to one output:
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- Bit 0 controls Output 1
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- Bit 1 controls Output 2
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- etc.
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### Msg
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```
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Byte 0: Slave Address (0x01)
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Byte 1: Function Code (0x06)
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Byte 2: Register Address High (0x00)
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Byte 3: Register Address Low (0x00)
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Byte 4: Data High Byte
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Byte 5: Data Low Byte
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Byte 6: CRC Low Byte
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Byte 7: CRC High Byte
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```
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