I want to interface ADXl345 with nrf51 SDK. suppoose my device address is 0x53 and register address is 0x2D and i want to write value 8. now nordic i2c has function nrf_drv_twi_tx with attributes nrf_drv_twi_t const *const p_instance, uint8_t address, uint8_t const * p_data, uint32_t length, bool xfer_pending
now here my address is 0x53, length is 6. now can you tell me where to write register address? where to write data??
This should do it (includes the setup):
//global variables
static uint8_t data[2] = {0x2D, 8}; //contains register + data to be written to register
#define ADXL345_ADDR 0x53U
//local code
uint32_t ret_code;
static const nrf_drv_twi_t p_twi_instance = NRF_DRV_TWI_INSTANCE(0);
const nrf_drv_twi_config_t p_twi_config = {
.scl = SCL_PIN,
.sda = SDA_PIN,
.frequency = NRF_TWI_FREQ_400K,
.interrupt_priority = APP_IRQ_PRIORITY_LOW
};
//Initiate twi driver with instance and configuration values
ret_code = nrf_drv_twi_init(&p_twi_instance, &p_twi_config, twi_handler, NULL);
APP_ERROR_CHECK(ret_code); // Check for errors in return value
nrf_drv_twi_enable(&p_twi_instance); // Enable the TWI instance
ret_code = nrf_drv_twi_tx(&p_twi_instance, ADXL345_ADDR, data, sizeof(data), false);
thanks for help.
void twi_handler(nrf_drv_twi_evt_t const * p_event, void * p_context)
{
ret_code_t err_code;
static sample_t m_sample;
switch(p_event->type)
{
case NRF_DRV_TWI_RX_DONE:
// read_data(&m_sample);
read_data();
m_xfer_done = true;
break;
case NRF_DRV_TWI_TX_DONE:
if(m_set_mode_done != true)
{
m_set_mode_done = true;
return;
}
m_xfer_done = false;
/* Read 4 bytes from the specified address. */
// err_code = nrf_drv_twi_rx(&m_twi_mma_7660, MMA7660_ADDR, (uint8_t*)&m_sample, sizeof(m_sample), false);
err_code = nrf_drv_twi_rx(&m_twi_adxl_345,ADXL345_ADDR,(uint8_t*)&m_sample, sizeof(m_sample), false);
APP_ERROR_CHECK(err_code);
break;
default:
break;
}
}
this twi_handler is confusing me much. what is its use.can you tell me? how to use it?
The twi handler will be called when the transfer is done or an error condition is met (e.g. NACK recevied).
void twi_handler(nrf_drv_twi_evt_t const * p_event, void * p_context)
{
switch(p_event->type)
{
case NRF_DRV_TWI_RX_DONE:
//code to be run when RX done (nrf_drv_twi_rx done)
//For example check the data that was received
break;
case NRF_DRV_TWI_TX_DONE:
//code to be run when TX done (nrf_drv_twi_tx done)
//For example start reading register if this was sent with nrf_drv_twi_tx
//with xfer pending equals true
break;
default:
break;
}
}
can we remove it if i dont want to use it? with initializing NULL in nrf_drv_twi_init
#include <stdio.h> #include "boards.h" #include "app_util_platform.h" #include "app_uart.h" #include "app_error.h" #include "nrf_drv_twi.h"
#define ARDUINO_I2C_SCL_PIN 7
#define ARDUINO_I2C_SDA_PIN 30
#define UART_TX_BUF_SIZE 256
#define UART_RX_BUF_SIZE 1
#define ADXL345_ADDR 0x53U
#define ADXL345_REG_MODE 0x2DU
#define ACTIVE_MODE 8u
#define NUMBER_OF_SAMPLES 20
static volatile bool m_set_mode_done;
static const nrf_drv_twi_t m_twi_adxl_345 = NRF_DRV_TWI_INSTANCE(0);
//uart
static void uart_events_handler(app_uart_evt_t * p_event)
{
switch (p_event->evt_type)
{
case APP_UART_COMMUNICATION_ERROR:
APP_ERROR_HANDLER(p_event->data.error_communication);
break;
case APP_UART_FIFO_ERROR:
APP_ERROR_HANDLER(p_event->data.error_code);
break;
default:
break;
}
}
static void uart_config(void)
{
uint32_t err_code;
const app_uart_comm_params_t comm_params =
{
RX_PIN_NUMBER,
TX_PIN_NUMBER,
RTS_PIN_NUMBER,
CTS_PIN_NUMBER,
APP_UART_FLOW_CONTROL_DISABLED,
false,
UART_BAUDRATE_BAUDRATE_Baud38400
};
APP_UART_FIFO_INIT(&comm_params,
UART_RX_BUF_SIZE,
UART_TX_BUF_SIZE,
uart_events_handler,
APP_IRQ_PRIORITY_LOW,
err_code);
APP_ERROR_CHECK(err_code);
}
void ADXL345_set_mode(void)
{ret_code_t err_code;
uint8_t reg[2] = {ADXL345_REG_MODE, ACTIVE_MODE};
err_code = nrf_drv_twi_tx(&m_twi_adxl_345,ADXL345_ADDR , reg, sizeof(reg), false);
while(m_set_mode_done == false);
}
uint16_t read_data(nrf_drv_twi_t const * const m_twi_adxl_345,uint8_t i2cAddress, uint8_t reg)
{
uint32_t err_code;
uint8_t data[2] = {0, 0};
uint8_t value;
err_code = nrf_drv_twi_tx(m_twi_adxl_345,ADXL345_ADDR , data, sizeof(data), false);
APP_ERROR_CHECK(err_code);
err_code = nrf_drv_twi_rx(m_twi_adxl_345,ADXL345_ADDR,data,sizeof(data),false);
value = (data[0] << 8) | data[1];
return value;
}
void write_data(nrf_drv_twi_t const * const m_twi_adxl_345,uint8_t i2cAddress, uint8_t reg) {
uint8_t tx_data[3];
uint32_t err_code;
tx_data[0] = (uint8_t)reg;
err_code = nrf_drv_twi_tx(m_twi_adxl_345,ADXL345_ADDR , tx_data, sizeof(tx_data), false);
APP_ERROR_CHECK(err_code);
}
void twi_init (void)
{
ret_code_t err_code;
const nrf_drv_twi_config_t twi_adxl_345_config = {
.scl = ARDUINO_SCL_PIN,
.sda = ARDUINO_SDA_PIN,
.frequency = NRF_TWI_FREQ_100K,
.interrupt_priority = APP_IRQ_PRIORITY_HIGH // interrupt priority
};
err_code = nrf_drv_twi_init(&m_twi_adxl_345, &twi_adxl_345_config, NULL, NULL);
APP_ERROR_CHECK(err_code);
nrf_drv_twi_enable(&m_twi_adxl_345);
}
int main(void)
{
uart_config();
uint8_t a;
printf("\n\rTWI sensor example\r\n");
twi_init();
ADXL345_set_mode();
write_data(&m_twi_adxl_345,ADXL345_ADDR,0x32);
a = read_data(&m_twi_adxl_345,ADXL345_ADDR,0x32);
printf("%d",a);
}
hey it is my finle code. but still not getting data