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【MCU】CH591用软件 I2C 出现的 bug

article 2025/1/21 8:52:05

计算问题

写软件 I2C 时不支持

byte |= (0x80 >> i);

详细：

/**
 * @brief Receive one byte using I2C
 * @param XACK
 * @retval Byte
 */
uint8_t SW_I2C_ReceiveByte(uint8_t XACK)
{
	SW_I2C_SDA_SetInput();
	uint8_t byte = 0x00;
	for (uint8_t i = 0; i < 8; i++)
	{
		SW_I2C_Delay();
		SW_I2C_SCL_WriteBit(1);
		if (SW_I2C_SDA_ReadBit() == 1)
		{
			byte |= (0x80 >> i);
		}
		SW_I2C_Delay();
		SW_I2C_SCL_WriteBit(0);
		SW_I2C_Delay();
	}
	SW_I2C_SDA_SetOutput();
	// transmit ACK
	SW_I2C_SDA_WriteBit(XACK);
	SW_I2C_Delay();
	SW_I2C_SCL_WriteBit(1);
	SW_I2C_Delay();
	SW_I2C_SCL_WriteBit(0);
	// release SDA
	SW_I2C_SDA_WriteBit(1);
	SW_I2C_Delay();
	return byte;
}

如果改成

/**
 * @brief Receive one byte using I2C
 * @param XACK
 * @retval Byte
 */
uint8_t SW_I2C_ReceiveByte(uint8_t XACK)
{
	SW_I2C_SDA_SetInput();
	uint8_t byte = 0x00;
	for (uint8_t i = 0; i < 8; i++)
	{
		byte<<=1;
		SW_I2C_Delay();
		SW_I2C_SCL_WriteBit(1);
		if (SW_I2C_SDA_ReadBit() == 1)
		{
			byte |= 0x01;
		}
		SW_I2C_Delay();
		SW_I2C_SCL_WriteBit(0);
		SW_I2C_Delay();
	}
	SW_I2C_SDA_SetOutput();
	// transmit ACK
	SW_I2C_SDA_WriteBit(XACK);
	SW_I2C_Delay();
	SW_I2C_SCL_WriteBit(1);
	SW_I2C_Delay();
	SW_I2C_SCL_WriteBit(0);
	// release SDA
	SW_I2C_SDA_WriteBit(1);
	SW_I2C_Delay();
	return byte;
}