Posted on April 05, 2016 at 12:57Hi,
I am trying to build a slave using a STM32F103. I've got the ''Optimized I2C Examples'' project to use it as a base and I get the idea of what is happening.
The bit I am stuck at is finding a way to check if master is trying to read or write. I cannot seem to find any info in the reference manual.
In my I2C2_EV_IRQHandler I've implemented the I2C_EVENT_SLAVE_RECEIVER_ADDRESS_MATCHED and I can see it being matched if I try to read or write from master, but cannot find a way to let slave identify what master wants.
(The my.st forum won't let me add code properly as the site seems to have an error)
void I2C2_EV_IRQHandler(void)
{
__IO uint32_t SR1Register =0;
__IO uint32_t SR2Register =0;
/* Read the I2C2 SR1 and SR2 status registers */
SR1Register = I2C2->SR1;
SR2Register = I2C2->SR2;
/* If I2C2 is slave (MSL flag = 0) */
if (I2C_GetFlagStatus(I2C2,I2C_FLAG_MSL) == RESET)
{
/* If ADDR = 1: EV1 */
if (I2C_CheckEvent(I2C2,I2C_EVENT_SLAVE_RECEIVER_ADDRESS_MATCHED))
{
regVal = I2C_ReadRegister(I2C2,I2C_Register_OAR1);
/* Clear SR1Register SR2Register variables to prepare for next IT*/
SR1Register = 0;
SR2Register = 0;
/* Initialize the transmit/receive counters for next transmission/reception
using Interrupt */
Tx_Idx2 = 0;
Rx_Idx2 = 0;
fs = I2C_GetFlagStatus(I2C2,I2C_FLAG_TRA);
}
/* If TXE = 1: EV3 */
if ((SR1Register & 0x0080) == 0x0080)
{
/* Write data in data register */
I2C2->DR = Buffer_Tx2[Tx_Idx2++];
SR1Register = 0;
SR2Register = 0;
}
/* If RXNE = 1: EV2 */
if (I2C_CheckEvent(I2C2,I2C_EVENT_SLAVE_BYTE_RECEIVED))
{
/* Read data from data register */
Buffer_Rx2[Rx_Idx2++] = I2C2->DR;
SR1Register = 0;
SR2Register = 0;
}
/* If STOPF =1: EV4 (Slave has detected a STOP condition on the bus */
if (( SR1Register & 0x0010) == 0x0010)
{
I2C2->CR1 |= CR1_PE_Set;
SR1Register = 0;
SR2Register = 0;
}
} /* End slave mode */
/* If SB = 1, I2C1 master sent a START on the bus: EV5) */
if ((SR1Register &0x0001) == 0x0001)
{
/* Send the slave address for transmssion or for reception (according to the configured value
in the write master write routine */
I2C1->DR = Address;
SR1Register = 0;
SR2Register = 0;
}
}
#i2c-slave-stm32f1
