I am using an nRF51422 and attempting to interface it with an MPU9150/6050 using your MPU6050 driver and the underlying twi_hw_master.c.
I have modified twi_master_config.h to match my board topology (Pin 10 - clk, Pin 11 - data).
twi_master_init() returns a success. If I change the pins in twi_master.config.h to open pins it fails. This is expected and indicates that TWI is seeing something.
MPU650_init() returns a failure. Digging in with the debugger shows that it is getting a timeout trying to do a simple register read.
An oscilloscope on SDA, SCL shows no activity.
I tried twi_sw_master.c and it just hangs after doing the twi_master_init().
I have the soft device (S310) loaded but am not getting hard faults. Just timeouts.
I hacked my board and used an Arduino to drive the MPU9050's SCL and SDA at address 0x68 (D0). This works, indicating the board itself is not apparently the issue.
Other sample code seems to indicate that the MPU9050 needs a wakeup by sending an 0x80 to the MPU6050_RA_PWR_MGMT_1 register, followed in 100ms by a 0x00. This did not work either.
Your docs seem to indicate I don't need to do any GPIO setup (taken care of in TWI) unless I want predictable behavior in power down mode. I haven't done this since it appears not to be necessary.
In my main.c, and twi_hw_master.c Keil complains about the include for nrf_delay.h. A development zone post seems to indicate this is Ok and has to do with ASM pragma used to generate the microsecond delay.
Any help appreciated.
Tom
