Hello,
I have a nRF51DK. I am trying to use the TWI driver to communicate via I2C with an accelerometer MMA8452Q. I already have a working code based on several SDK examples : basically it is based on the "experimental : multiactivity" example with a custom BLE service. Softdevice S130. As I said I try to add TWI support to get the data from the accelerometer and transfer the data over BLE. On the hardware side, I have a separate 3.3V to supply the accelerometer and I connect directly the SCL pin to the P0.07 pin of the nRF51DK and the SDA pin to the P0.30 pin of the nRF51DK. On the software side, I have added to my working code :
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a call to twi_init() in the main function
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the function twi_init() itself, based on the SDK TWI sensor example
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after the call of twi_init in the main function, a first call to nrf_drv_twi_tx is performed in order to set the accelerometer in active mode. I then expect a call to the TWI event handler to say "NRF_DRV_TWI_TX_DONE", but the handler is never called.
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the TWI event handler function twi_evt_handler itself
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I added a timer event every 2000 ticks to initiate a read action on the I2C bus; the handler is named accelerometer_sample_read_timeout_handler
As written above, the TWI event handler is not called after the first write action (set the sensor in active mode). However, if I disconnect the wires between the nRF51DK and the sensor the handler is immediately called with the "NRF_DRV_TWI_ERROR" event (NRF_TWI_ERROR_ADDRESS_NACK).
I guess I must be doing something wrong but I can't figure out what. Could you please help me? Attached is the main.c and the MMA8452Q.h (containing the registers defines).
Thanks a lot in advance for your help. main.c MMA8452Q.h
