twi sensor

[hardnrf]

i am programming nrf-51 dk's program.

i have to get data from sensor, so i am studying example code which is twi_sensor.

i don't know well these function.

nrf_drv_twi_tx(&m_twi_mma_7660, MMA7660_ADDR, reg, sizeof(reg), false);

i know function's parameters is

[in] p_instance TWI instance.
[in] address Address of a specific slave device (only 7 LSB).
[in] p_data Pointer to a transmit buffer.
[in] length Number of bytes to send.
[in] xfer_pending After a specified number of bytes, transmission will be suspended (if xfer_pending is set) or stopped (if not).

but how do i know TWI instance and address Address of a specific slave device?

the example code's parameters that is m_twi_mma_7660, MMA7660_ADDR are acceleration sensor's instance and address.

but i'm going to use heart rate sensor.

and when i execute the example program, nrf_drv_twi_tx returns error.

so it is locked at 'while(m_set_mode_done == false);'.

what is the problem?

ret_code_t err_code;
/* Writing to MMA7660_REG_MODE "1" enables the accelerometer. */
uint8_t reg[2] = {MMA7660_REG_MODE, ACTIVE_MODE};

err_code = nrf_drv_twi_tx(&m_twi_mma_7660, MMA7660_ADDR, reg, sizeof(reg), false);  

APP_ERROR_CHECK(err_code);

while(m_set_mode_done == false);

please let me know. i need help....

[hong min]

Please remind always check the hardware at first , almost troubles from hardware side.

1. Check the pin assign as same as the software defined
2. Check the voltage of VDD/SDA/SCL pins
3. Check the the device address , if its a flexible addressing device ,make sure the schematic is same as you defined in software.
4. Check your pin assign to arduino .

After check the hardware finish. Next check the timing digram is correct by using oscilloscope or i2c logic analyzer. If it not same as sensor specification , it strongly problem in software.

[Ole Bauck]

Why would you do make a bit-bang protocol when you have a hardware driver? Also the SDK have a bit-bang driver that is called tw_sw_master.

Anyhow, the problem is probably with the pins used, connecting a oscilloscope or logic analyzer would be a smart.

[Ole Bauck]

which arduino shield? Are the correct pins used?