Dear All,
I will connect MS4525DO pressure sensor via I2c. this sensor respond with four bytes .
the protocol is working as follow :
1- start condition : device salve address [6:0] - Read/Write bit (read=1)
2- wait for slave ACK
3-read the first byte : 2 status bits - 6 pressure bits [13:8]
4-master ACK
5-when the slave receive the master ACK, then it will send the second byte ; read the second byte : 8 pressure bits[7:0]
6-master ACK
7-read the third byte ; 8 temprature bits [10:3]
8- master ACK
9- read the forth byte ;3 temperature bits [2:0] and the others bits are don't care
10- master NACK
so here is the code for reading 4 bytes :
ROM_I2CMasterSlaveAddrSet(I2C1_BASE, slave_addr, true); // read operation
I2CMasterControl (I2C1_BASE, I2C_MASTER_CMD_BURST_RECEIVE_START); //
// ROM_SysCtlDelay((ui32SysClkFreq / 3) * (1 / 1000.0f));//time_in_ms // just for polling as the tm4c129 is 120mhz and fast
while (I2CMasterBusy(I2C1_BASE)); //Wait till end of transaction
L1 = (uint8_t)(I2CMasterDataGet (I2C1_BASE)); //Read from FIFO (1st byte)
I2CMasterControl (I2C1_BASE, I2C_MASTER_CMD_BURST_RECEIVE_CONT);
//ROM_SysCtlDelay((ui32SysClkFreq / 3) * (5 / 1000.0f));//time_in_ms
while (I2CMasterBusy(I2C1_BASE)); //Wait till end of transaction
L2 = (uint8_t)(I2CMasterDataGet (I2C1_BASE)); //Read from FIFO' ( read the second byte)
I2CMasterControl (I2C1_BASE, I2C_MASTER_CMD_BURST_RECEIVE_CONT);
//ROM_SysCtlDelay((ui32SysClkFreq / 3) * (5 / 1000.0f));//time_in_ms
while (I2CMasterBusy(I2C1_BASE)); //Wait till end of transaction
L3 = (uint8_t)(I2CMasterDataGet (I2C1_BASE)); //Read from FIFO (Read the 3rd Byte)
I2CMasterControl (I2C1_BASE, I2C_MASTER_CMD_BURST_RECEIVE_FINISH); //Read the 2nd Byte
//ROM_SysCtlDelay((ui32SysClkFreq / 3) * (5 / 1000.0f));//time_in_ms
while (I2CMasterBusy(I2C1_BASE)); //Wait till end of transaction
//Wait till end of transaction
L4 = (uint8_t)(I2CMasterDataGet (I2C1_BASE)); //Read from FIFO (Read the 4th Byte)
now my problem is with "Master ACK"
does the "I2C_MASTER_CMD_BURST_RECEIVE_CONT" send the ack to the slave to send the next byte , and the I2C_MASTER_CMD_BURST_RECEIVE_FINISH send NACK or not?
or how can I send Master ACK ?
is the code characterized the protocol ?
