AM6442: MCU+ SDK 8.1: I2C Slave example

Hi Gunter,

Yes, you are correct. In MCU+ SDK, there is no I2C slave examples, but the I2C driver does support slave mode (no slave polling mode support though).

In mcu_plus_sdk_am64x_08_01_00_36\source\drivers\i2c\v0\i2c_v0.c, there is I2C_defaultTransaction which defines the default I2C mode as master mode. You should be able to change the .masterMode from "true" to "false". You may have to make a few changes in the example to make it works for slave mode.

Best regards,

Ming

Hi Ming,

Thanks. I went ahead and tried setting up an I2C slave example. Essentially there are two modified example codes that I am using on the AM64xx Starterkit

[1] R5F0-0: I2C read example reading on I2C0 with slave address 0x50 (i validated this working correctly with slave address 0x51 to read the EEPROM, it works)

[2] R5F1-0: I2C slave write example writing on I2C2 a value back to the master, it has slave address 0x50

[3] On the AM64xx SK, the I2C0 and I2C2 are connected with wires, so the R5F1-0 I2C2 should appear as a slave on the Master I2C0 bus

But the observation is that the I2C2 slave code is pending on the transaction complete semaphore and never completes, i.e. gets a post on that semaphore. It seems the I2C2 slave is not seeing the I2C0 Master transaction.

As a sanity check here is the code on the I2C2 Slave side

The I2C2 Slave has a modified sysconfig to configure the pins and I2C2 port.

#define I2C_SLAVE_ADDR                  (0x50U)
#define I2C_WRITE_LEN                   (1U)

static void i2c_slave_write_error_handler(uint16_t sample, int32_t status);

void i2c_slave_write_main(void *arg0)
{
    uint16_t        sample;
    int32_t         status;
    uint8_t         txBuffer[I2C_WRITE_LEN];
    I2C_Handle      i2cHandle;
    I2C_Transaction i2cTransaction;

    Drivers_open();
    Board_driversOpen();

    i2cHandle = gI2cHandle[CONFIG_I2C2];

    DebugP_log("[I2C SLAVE] Write data from slave to master ... !!!\r\n");

    /* Set default transaction parameters */
    I2C_Transaction_init(&i2cTransaction);

    /* Override with required transaction parameters */
    i2cTransaction.writeBuf     = txBuffer;
    i2cTransaction.writeCount   = I2C_WRITE_LEN;
    i2cTransaction.slaveAddress = I2C_SLAVE_ADDR;
    i2cTransaction.masterMode   = FALSE;
    txBuffer[0] = 0xAA;

    /* Read 20 samples and log them */
    for(sample = 0; sample < 20; sample++)
    {
        status = I2C_transfer(i2cHandle, &i2cTransaction);
        if(status == I2C_STS_SUCCESS)
        {
            DebugP_log("[I2C SLAVE] Sample written to master %u: %u\r\n", sample, txBuffer[0]);
        }

On the I2C0 Master side, the code is this

#define I2C_READ_SLAVE_ADDR             (0x50U)
#define I2C_READ_LEN                    (1U)

static void i2c_read_error_handler(uint16_t sample, int32_t status);

void i2c_read_main(void *arg0)
{
    uint16_t        sample;
    int32_t         status;
    uint8_t         rxBuffer[I2C_READ_LEN];
    I2C_Handle      i2cHandle;
    I2C_Transaction i2cTransaction;

    Drivers_open();
    Board_driversOpen();

    i2cHandle = gI2cHandle[CONFIG_I2C0];

    DebugP_log("[I2C] Read data ... !!!\r\n");

    /* Set default transaction parameters */
    I2C_Transaction_init(&i2cTransaction);

    /* Override with required transaction parameters */
    i2cTransaction.readBuf      = rxBuffer;
    i2cTransaction.readCount    = I2C_READ_LEN;
    i2cTransaction.slaveAddress = I2C_READ_SLAVE_ADDR;

    /* Read 20 samples and log them */
    for(sample = 0; sample < 20; sample++)
    {
        status = I2C_transfer(i2cHandle, &i2cTransaction);
        if(status == I2C_STS_SUCCESS)
        {
            DebugP_log("[I2C] Sample %u: %u\r\n", sample, rxBuffer[0]);
        }

Could you are someone from the apps team review this, to see if anything is missing?

Thanks,

--Gunter

Hi Gunter,

The code look good to me.

Best regards,

Ming