How to transmit data bytes from an I2C master device using polling mode to an I2C slave device using interrupt mode. The peripheral is initialized with LL unitary service functions to optimize for performance and size.
This example guides you through the different configuration steps by mean of LL API to configure GPIO and I2C peripherals using two NUCLEO-C031C6.
Boards: NUCLEO-C031C6 (embeds a STM32C031C6 device)
- SCL Pin: PB.8 (CN10, pin 3)
- SDA Pin: PB.9 (CN10, pin 5)
The project is split in two parts the Master Board and the Slave Board
Master Board: I2C1 Peripheral is configured in Master mode (Clock 400Khz). And GPIO associated to User push-button is linked with EXTI.
Slave Board: I2C1 Peripheral is configured in Slave mode (Clock 400Khz, Own address 7-bit enabled).
The user can choose between Master and Slave through “#define SLAVE_BOARD” in the “main.h” file:
The user can disable internal pull-up by opening ioc file. For that, user can follow the procedure :
1- Double click on the I2C_TwoBoards_MasterTx_SlaveRx_Init.ioc file 2- When CUBEMX tool is opened, select System Core category 3- Then in the configuration of GPIO/I2C1, change Pull-up to No pull-up and no pull-down for the both pins 4- Last step, generate new code thanks to button “GENERATE CODE”
The example is updated with no pull on each pin used for I2C communication
A first program launch, BOARD SLAVE waiting Address Match code through Handle_I2C_Slave() routine.
LED4 blinks quickly on BOARD MASTER to wait for User push-button press.
Example execution:
Press the User push-button on BOARD MASTER to initiate a write request by Master through Handle_I2C_Master() routine. This action will generate an I2C start condition with the Slave address and a write bit condition. When address Slave match code is received on I2C1 of BOARD SLAVE, an ADDR event occurs. Handle_I2C_Slave() routine is then checking Address Match Code and direction Write. This will allow Slave to enter in receiver mode and then acknowledge Master to send the bytes. When acknowledge is received on I2C1 (Master), a TXIS event occurs. This will allow Master to transmit a byte to the Slave. Each time a byte is received on I2C1 (Slave), an RXNE event occurs until a STOP condition. And so each time the Slave acknowledge the byte received a TXIS event occurs on Master side. Master auto-generate a Stop condition when size of data to transmit is achieved.
The STOP condition generate a STOP event and initiate the end of reception on Slave side. Handle_I2C_Slave() and Handle_I2C_Master() routine are then clearing the STOP flag in both side.
LED4 is On :
In case of errors, LED4 is blinking slowly (1s).
Connectivity, Communication, I2C, Master Rx, Slave Tx, Transmission, Reception, Fast mode, SDA, SCL
This example runs on STM32C031C6Tx devices.
This example has been tested with STM32C031C6Tx board and can be easily tailored to any other supported device and development board.
NUCLEO-C031C6 Set-up
Launch the program.
Press User push-button to initiate a write request by Master then Slave receive bytes.
In order to make the program work, you must do the following :