43 lines
1.3 KiB
Markdown
43 lines
1.3 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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## Communication Protocol
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### Message Format
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The RS485 communication uses a simple 4-byte message format:
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```
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Byte 0: Board Address (0x01-0xFE, 0xFF for broadcast)
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Byte 1: Command (0x01 for SET_OUTPUTS)
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Byte 2: Data High Byte
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Byte 3: Data Low Byte
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```
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### Protocol Constants
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```c
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#define BOARD_ADDRESS 0x01 // Default board address
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#define CMD_SET_OUTPUTS 0x01 // Command to set outputs
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#define BROADCAST_ADDR 0xFF // Broadcast address
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```
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### Example Message
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To control the outputs, send a 4-byte message:
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```rust
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let message = [
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address, // Board address (0xFF for broadcast)
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CMD_SET_OUTPUTS, // Command
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(value >> 8) as u8, // Data high byte
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value as u8, // Data low byte
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];
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```
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