ch32v203-bms

A simple battery management controller software.

CAN bus and hardware address

This firmware exposes a CAN interface on the CH32V203 and uses 4 hardware address pins to allow up to 16 sensors on the same bus.

CAN pins (default mapping):
- CAN RX: PA11
- CAN TX: PA12
Address select pins (with internal pull-ups):
- A0: PA0
- A1: PA1
- A2: PA2
- A3: PA3

Wire each address pin to GND to set its corresponding bit to 1. The 4-bit address range is 0..15. The node’s CAN Standard ID is 0x100 | addr, i.e. 0x100..0x10F. The CAN acceptance filter is configured to only accept frames with the node’s own ID.

Adjust the pins above if your PCB routes CAN or address lines to different pads.

555 timer (software) emulation mode

To save the BOM cost of a classic NE555 in simple oscillator applications, this firmware implements a minimal 555-like Schmitt trigger using the MCU’s ADC and a GPIO, approximating the behavior when the capacitor is charged/discharged via Q through a resistor, and the combined Trigger/Threshold senses the capacitor node.

Pins used:
- Q output: PB2
- Combined Trigger/Threshold (ADC input): PA0
Wiring:
- PB2 (Q) -> series resistor R -> capacitor node
- Capacitor node -> capacitor to GND
- Capacitor node -> PA0 (ADC input)
Behavior:
- When ADC(PA0) <= ~1/3 Vref, PB2 is driven High.
- When ADC(PA0) >= ~2/3 Vref, PB2 is driven Low.
- Hysteresis avoids chatter; the actual charge/discharge dynamics follow your chosen R and C.
Notes:
- Use an appropriate resistor from PB2 to the capacitor to set oscillation frequency. Start with 10k..100k and adjust with C.
- Ensure PA0 is routed to the capacitor node and left high impedance (no strong pull-ups/downs) so the ADC can sense the analog voltage.
- PB2 drives the on-board LED (if present), so the LED might blink at the oscillation frequency.

This mode is implemented in src/main.rs using hal::adc::Adc::convert(&mut pin, SampleTime::...) to take periodic samples and a simple state machine to toggle the Q output based on ~1/3 and ~2/3 Vref thresholds.

Building

cargo build --release

Flash

wchisp config reset
wchip wchisp flash target/riscv32imc-unknown-none-elf/release/bms

Debugging

For debugging purposes a container file is provided together with wrapper scripts to start the containerized openocd and riscv-gdb transparently. The wrapper scripts assume that podman is setup.

Starting Debug server

./bin/openocd

Connecting with gdb for interactive debugging

./bin/gdb -f target/riscv32imc-unknown-none-elf/release/bms

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