Posted on September 01, 2013 at 18:26Hello,
I am trying to get the I2C bus to run with the MMA8452 accelerometer, but it just wont.
I can generate a start condition but nothing else. I'm watching the bus lines with a scope/logic analyzer and I can see that it doesn't generate anything after the start condition on SCL/SDA.
In debug mode I also noticed that after writing to the I2C data register the ''AF - acknowledge failure'' bit is set in SR1
The code:
RCC_AHB1PeriphClockCmd(RCC_AHB1Periph_GPIOB | RCC_AHB1Periph_GPIOA, ENABLE);
GPIO_InitTypeDef GPIO_InitStructure;
GPIO_InitStructure.GPIO_Pin = GPIO_Pin_10 | GPIO_Pin_11;
GPIO_InitStructure.GPIO_Mode = GPIO_Mode_AF;
GPIO_InitStructure.GPIO_Speed = GPIO_Speed_50MHz;
GPIO_Init(GPIOB, &GPIO_InitStructure);
GPIO_PinAFConfig(GPIOB, GPIO_PinSource10, GPIO_AF_I2C2);
GPIO_PinAFConfig(GPIOB, GPIO_PinSource11, GPIO_AF_I2C2);
RCC_APB1PeriphClockCmd(RCC_APB1Periph_I2C2, ENABLE);
I2C_InitTypeDef I2C_InitStruct;
I2C_InitStruct.I2C_Ack = I2C_Ack_Enable;
I2C_InitStruct.I2C_AcknowledgedAddress = I2C_AcknowledgedAddress_7bit;
I2C_InitStruct.I2C_ClockSpeed = 100000;
I2C_InitStruct.I2C_DutyCycle = I2C_DutyCycle_2;
I2C_InitStruct.I2C_Mode = I2C_Mode_I2C;
I2C_InitStruct.I2C_OwnAddress1 = 0;
I2C_Init(I2C2, &I2C_InitStruct);
I2C_Cmd(I2C2, ENABLE);
GPIO_InitStructure.GPIO_Pin = GPIO_Pin_0;
GPIO_InitStructure.GPIO_Mode = GPIO_Mode_IN;
GPIO_InitStructure.GPIO_Speed = GPIO_Speed_50MHz;
GPIO_Init(GPIOA, &GPIO_InitStructure);
GPIO_InitStructure.GPIO_Pin = GPIO_Pin_5;
GPIO_InitStructure.GPIO_Mode = GPIO_Mode_OUT;
GPIO_InitStructure.GPIO_Speed = GPIO_Speed_50MHz;
GPIO_Init(GPIOA, &GPIO_InitStructure);
while(!GPIO_ReadInputDataBit(GPIOA, GPIO_Pin_0));
GPIO_SetBits(GPIOA, GPIO_Pin_5); //Trigger for analyzer
I2C_GenerateSTART(I2C2, ENABLE);
I2C_Send7bitAddress(I2C2, 0x3A, I2C_Direction_Transmitter);
while(1);
Any suggestions?
