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Writing BLE firmware with a few lines of code part 2

Nguyen Hoan Hoang

Second part of the series Writing Bluetooth LE firmware the easy way blog. This second part shows how to read and advertise the environment sensor data (BME280 using Motsai Neblina module and BME680 using breakout board). Still with only a few lines of code. See blog page here.

Complete code bellow advertise Temperature, Pressure, Humidity data from #BME680 & #BME280.

#define DEVICE_NAME                     "EnvSensorTag"                            /**< Name of device. Will be included in the advertising data. */

#ifdef NEBLINA_MODULE
#define TPH_BME280
#else
#define TPH_BME680
#endif

#ifdef NRF52
// Use timer to update data
// NOTE :	RTC timer 0 used by radio, RTC Timer 1 used by SDK
//			Only RTC timer 2 is usable with Softdevice for nRF52, not avail on nRF51
//
//#define USE_TIMER_UPDATE
#endif

#define APP_ADV_INTERVAL                MSEC_TO_UNITS(200, UNIT_0_625_MS)             /**< The advertising interval (in units of 0.625 ms. This value corresponds to 40 ms). */
#ifdef USE_TIMER_UPDATE
// Use timer to update date
#define APP_ADV_TIMEOUT_IN_SECONDS      0                                         /**< The advertising timeout (in units of seconds). */
#else
// Use advertisement timeout to update data
#define APP_ADV_TIMEOUT_IN_SECONDS      1                                         /**< The advertising timeout (in units of seconds). */
#endif

void TimerHandler(Timer *pTimer, uint32_t Evt);

uint8_t g_AdvDataBuff[9] = {
	BLEADV_MANDATA_TYPE_TPH,
};

BLEADV_MANDATA &g_AdvData = *(BLEADV_MANDATA*)g_AdvDataBuff;

// Evironmental Sensor Data to advertise
BLEADV_MANDATA_TPHSENSOR &g_TPHData = *(BLEADV_MANDATA_TPHSENSOR *)g_AdvData.Data;
BLEADV_MANDATA_GASSENSOR &g_GasData = *(BLEADV_MANDATA_GASSENSOR *)g_AdvData.Data;

const static TIMER_CFG s_TimerCfg = {
    .DevNo = 1,
	.ClkSrc = TIMER_CLKSRC_DEFAULT,
	.Freq = 0,			// 0 => Default highest frequency
	.IntPrio = APP_IRQ_PRIORITY_LOW,
	.EvtHandler = TimerHandler
};

TimerLFnRF5x g_Timer;

const BLEAPP_CFG s_BleAppCfg = {
	{ // Clock config nrf_clock_lf_cfg_t
#ifdef IMM_NRF51822
		NRF_CLOCK_LF_SRC_RC,	// Source RC
		1, 1, 0
#else
		NRF_CLOCK_LF_SRC_XTAL,	// Source 32KHz XTAL
		0, 0, NRF_CLOCK_LF_ACCURACY_20_PPM
#endif

	},
	0, 						// Number of central link
	0, 						// Number of peripheral link
	BLEAPP_MODE_NOCONNECT,   // Connectionless beacon type
	DEVICE_NAME,                 // Device name
	ISYST_BLUETOOTH_ID,     // PnP Bluetooth/USB vendor id
	1,                      // PnP Product ID
	0,						// Pnp prod version
	false,					// Enable device information service (DIS)
	NULL,
	(uint8_t*)&g_AdvDataBuff,   // Manufacture specific data to advertise
	sizeof(g_AdvDataBuff),      // Length of manufacture specific data
	BLEAPP_SECTYPE_NONE,    // Secure connection type
	BLEAPP_SECEXCHG_NONE,   // Security key exchange
	NULL,      				// Service uuids to advertise
	0, 						// Total number of uuids
	APP_ADV_INTERVAL,       // Advertising interval in msec
	APP_ADV_TIMEOUT_IN_SECONDS,	// Advertising timeout in sec
	100,                          // Slow advertising interval, if > 0, fallback to
								// slow interval on adv timeout and advertise until connected
	0,
	0,
	-1,		// Led port nuber
	-1,     // Led pin number
	0, 		// Tx power
	NULL						// RTOS Softdevice handler
};

// Motsai Neblina V2 module uses SPI interface
#ifdef NEBLINA_MODULE
static const IOPINCFG gsSpiBoschPin[] = {
    {SPI_SCK_PORT, SPI_SCK_PIN, SPI_SCK_PINOP,
     IOPINDIR_OUTPUT, IOPINRES_NONE, IOPINTYPE_NORMAL},
    {SPI_MISO_PORT, SPI_MISO_PIN, SPI_MISO_PINOP,
     IOPINDIR_INPUT, IOPINRES_NONE, IOPINTYPE_NORMAL},
    {SPI_MOSI_PORT, SPI_MOSI_PIN, SPI_MOSI_PINOP,
     IOPINDIR_OUTPUT, IOPINRES_NONE, IOPINTYPE_NORMAL},
    {BME280_CS_PORT, BME280_CS_PIN, BME280_CS_PINOP,
     IOPINDIR_OUTPUT, IOPINRES_PULLUP, IOPINTYPE_NORMAL},
};

static const SPICFG s_SpiCfg = {
    SPI_DEVNO,
    SPIMODE_MASTER,
    gsSpiBoschPin,
    sizeof( gsSpiBoschPin ) / sizeof( IOPINCFG ),
    8000000,   // Speed in Hz
    8,      // Data Size
    5,      // Max retries
    SPIDATABIT_MSB,
    SPIDATAPHASE_SECOND_CLK, // Data phase
    SPICLKPOL_LOW,         // clock polarity
    SPICSEL_AUTO,
    6, //APP_IRQ_PRIORITY_LOW,      // Interrupt priority
    nullptr
};

SPI g_Spi;

DeviceIntrf *g_pIntrf = &g_Spi;

#else

// Configure I2C interface
static const I2CCFG s_I2cCfg = {
	0,			// I2C device number
	{

#if defined(TPH_BME280) || defined(TPH_BME680)
		{I2C0_SDA_PORT, I2C0_SDA_PIN, I2C0_SDA_PINOP, IOPINDIR_BI, IOPINRES_NONE, IOPINTYPE_NORMAL},
		{I2C0_SCL_PORT, I2C0_SCL_PIN, I2C0_SCL_PINOP, IOPINDIR_OUTPUT, IOPINRES_NONE, IOPINTYPE_NORMAL},
#else
		// Custom board with MS8607
		{0, 4, 0, IOPINDIR_BI, IOPINRES_NONE, IOPINTYPE_NORMAL},
		{0, 3, 0, IOPINDIR_OUTPUT, IOPINRES_NONE, IOPINTYPE_NORMAL},
#endif
	},
	100000,	// Rate
	I2CMODE_MASTER,
	0,			// Slave address
	5,			// Retry
	7,			// Interrupt prio
	NULL		// Event callback
};

// I2C interface instance
I2C g_I2c;

DeviceIntrf *g_pIntrf = &g_I2c;
#endif

// Configure environmental sensor
static TPHSENSOR_CFG s_TphSensorCfg = {
#ifdef NEBLINA_MODULE
    0,      // SPI CS index 0 connected to BME280
#else
	BME680_I2C_DEV_ADDR0,   // I2C device address
#endif
	SENSOR_OPMODE_SINGLE,
	100,						// Sampling frequency in Hz
	1,
	1,
	1,
	1
};

// Environmental sensor instance
TphgBme680 g_Bme680Sensor;
TphBme280 g_Bme280Sensor;
TphMS8607 g_MS8607Sensor;


#ifdef TPH_BME280
TphSensor &g_TphSensor = g_Bme280Sensor;
#elif defined(TPH_BME680)
TphSensor &g_TphSensor = g_Bme680Sensor;
#else
TphSensor &g_TphSensor = g_MS8607Sensor;
#endif

void ReadPTHData()
{
	TPHSENSOR_DATA data;

	g_TphSensor.Read(data);
	g_TphSensor.StartSampling();

	g_AdvData.Type = BLEADV_MANDATA_TYPE_TPH;

	// NOTE : M0 does not access unaligned data
	// use local 4 bytes align stack variable then mem copy
	// skip timestamp as advertising pack is limited in size
	memcpy(&g_TPHData, ((uint8_t*)&data) + 4, sizeof(BLEADV_MANDATA_TPHSENSOR));

	// Update advertisement data
	BleAppAdvManDataSet(g_AdvDataBuff, sizeof(g_AdvDataBuff));
}

void TimerHandler(Timer *pTimer, uint32_t Evt)
{
    if (Evt & TIMER_EVT_TRIGGER(0))
    {
    	ReadPTHData();
    }
}

void BlePeriphEvtUserHandler(ble_evt_t * p_ble_evt)
{
#ifndef USE_TIMER_UPDATE
    if (p_ble_evt->header.evt_id == BLE_GAP_EVT_TIMEOUT)
    {
    	// Update environmental sensor data every time advertisement timeout
    	// for re-advertisement
    	ReadPTHData();
    }
#endif
}

void HardwareInit()
{
	// Set this only if nRF is power at 2V or more
	nrf_power_dcdcen_set(true);

	// Initialize I2C
#ifdef NEBLINA_MODULE
    g_Spi.Init(s_SpiCfg);
#else
    g_I2c.Init(s_I2cCfg);
#endif

	// Inititalize sensor
    g_TphSensor.Init(s_TphSensorCfg, g_pIntrf, NULL);
    g_TphSensor.StartSampling();

    // Update sensor data
    TPHSENSOR_DATA tphdata;
	g_TphSensor.Read(tphdata);

	g_AdvData.Type = BLEADV_MANDATA_TYPE_TPH;
	// Do memcpy to adv data. Due to byte alignment, cannot read directly into
	// adv data
	memcpy(g_AdvData.Data, ((uint8_t*)&tphdata) + 4, sizeof(BLEADV_MANDATA_TPHSENSOR));

#ifdef USE_TIMER_UPDATE
	// Only with SDK14
    g_Timer.Init(s_TimerCfg);
	uint64_t period = g_Timer.EnableTimerTrigger(0, 500UL, TIMER_TRIG_TYPE_CONTINUOUS);
#endif
}

int main()
{
    HardwareInit();

    BleAppInit((const BLEAPP_CFG *)&s_BleAppCfg, true);

    BleAppRun();

	return 0;
}