STM32 F302R8与ATmega328的I2C通信故障求助（附初始化代码）

Alright, let's tackle your I2C issue step by step. Based on the partial STM32 Cube-generated init code you shared, here are key areas to investigate and fix:

1. Verify STM32 I2C Timing Parameter #

Your timing value 0x2000090E corresponds to a standard 100kHz I2C clock (assuming your STM32 runs from its default clock source). Ensure this matches the I2C speed configured on your ATmega328:

• For an ATmega328 with a 16MHz crystal, set the TWI bit rate register (TWBR) to 72 to get 100kHz:

  TWBR = 72; // Calculation: ((16000000 / 100000) - 16) / 2 = 72
  TWCR = (1 << TWEN); // Enable TWI peripheral
  

• If you need 400kHz fast mode, recalculate the STM32 timing register using STM32CubeMX’s built-in timing calculator.

2. Fix STM32 Own Address Configuration #

Your code sets hi2c2.Init.OwnAddress1 = 0—this is only valid if the STM32 acts as an I2C host. If it’s a slave:

• Set a valid 7-bit address (e.g., 0x48—choose any address not reserved by other bus devices):

  hi2c2.Init.OwnAddress1 = 0x48; // 7-bit slave address, match this to your ATmega328's target address
  

• When the ATmega328 (as host) sends data, it appends a read/write bit to this address. For example, writing to the STM32 would use 0x90 (0x48 << 1 | 0).

3. Check Hardware Connections #

I2C relies on proper wiring and pull-up resistors:

• Connect SDA and SCL pins between the two MCUs. For STM32 F302R8, I2C2 uses PB10 (SCL) and PB11 (SDA) by default—confirm these pins aren’t assigned to other peripherals in CubeMX.
• Add 4.7kΩ pull-up resistors to both SDA and SCL lines, connected to your system’s VCC.
• If your ATmega328 runs on 5V and the STM32 on 3.3V, use a level shifter to prevent pin damage on the STM32.

4. Complete and Validate Cube-Generated Code #

Your code cuts off at Init.GeneralCallM...—ensure this is configured correctly:

• Disable general call mode unless you specifically need it:

  hi2c2.Init.GeneralCallMode = I2C_GENERALCALL_DISABLE;
  

• Double-check other settings: AddressingMode is set to 7-bit (standard for ATmega328 TWI), and DualAddressMode is disabled (correct if you only use one slave address).

5. Debug with Waveform Analysis #

If issues persist, use an oscilloscope or logic analyzer to capture SDA/SCL signals:

• Look for a valid start condition (SCL high, SDA falls low).
• Verify the address byte is sent correctly, followed by an ACK pulse from the slave.
• Check for bus conflicts (e.g., multiple devices driving SDA low simultaneously).

内容的提问来源于stack exchange，提问作者Robybyte