RE: Multi-instance TWI devices: style question & enhancement suggestion

bjorn-spockeli — Mon, 06 Mar 2017 13:27:58 GMT

Hi Ray, I agree that it appears that the app_twi library is designed to communicate with a single TWI device, i.e statically-compiled for a single I2C address as you put it. I will convey your feedback to the app_twi developer. In order to achieve the functionality you want, then I think that you will have to go down one abstraction layer and use the twi driver directly, i.e. nrf_drv_twi.c/h, instead of the TWI Transaction Manager library(app_twi) which in turn uses the driver.

RE: Multi-instance TWI devices: style question & enhancement suggestion

Nguyen Hoan Hoang — Fri, 03 Mar 2017 20:07:39 GMT

Perhaps you could have a look at the EHAL library from this blog. It's reusable object oriented multi-architecture. UART, SPI & I2C are available. An example for reading any EEPROM connected to I2C

static const I2CCFG s_I2C_CfgData = {
    0,  // i2c device number
    {
        { SDA_PORT, SDA_PIN, SDA_PINOP },
        { SCL_PORT, SCL_PIN, SCL_PINOP },
    },
    100000,     // Rate in Hz
    I2CMODE_MASTER,
    0,              // Device address (slave mode only)
    5,              // Maximum number of retries
    APP_IRQ_PRIORITY_LOW,      // Interrupt priority
   
};

I2C g_I2C_Instance;

static const I2CCFG s_I2C_CfgData2 = {
    1,  // i2c device number
    {
        { SDA_PORT, SDA_PIN, SDA_PINOP },
        { SCL_PORT, SCL_PIN, SCL_PINOP },
    },
    100000,     // Rate in Hz
    I2CMODE_MASTER,
    0,              // Device address (slave mode only)
    5,              // Maximum number of retries
    APP_IRQ_PRIORITY_LOW,      // Interrupt priority
   
};

I2C g_I2C_Instance2;

static const SEEP_CFG s_Eeprom_CfgData = {
    (0xA2 >> 1),    // Dev addr (7bits address)
    2,                   // Addressing length in bytes
    32,                 // Page size in bytes
    8192,              // 8KB eeprom
    5,                   // Write delays in sec
    {-1, -1, },
};
 
SEEP g_Eeprom_Instance;

int main()
{
    g_I2C_Instance.Init(s_I2C_CfgData);
    g_I2C_Instance2.Init(s_I2C_CfgData2);

    // use i2c0 instance 1
    g_Eeprom_Instance.Init(s_Eeprom_CfgData, &g_I2C_Instance);

    // use i2c1 instance 2
    g_Eeprom_Instance.Init(s_Eeprom_CfgData, &g_I2C_Instance2);

    uint8_t d[32];
    
    // Read 32 bytes eeprom at address 0x40
    // returns number of bytes read
    int count = g_Eeprom_Instance.Read(0x40, d, 32);

    // multiple devices using same I2C interface
    g_Dev2_Instance.Init(s_Dev2_CfgData, &g_I2C_Instance);
    count = g_Dev2_Instance.Read(0x40, d, 32);

    // your device can support SPI want to use SPI instead
    //
    g_SPI_Instance.Init(s_SPI_CfgData);

    // same eeprom now using SPI instead
    g_Eeprom_Instance.Init(s_Eeprom_CfgData, &g_SPI_Instance);

    count = g_Eeprom_Instance.Read(0x40, d, 32);
}

As simple as that. Same code on nRF5x, LPCxx series,..