nRF51 MPU9255 TWI/I2C READ Failed

[makerTim]

Hi all:

I used code from Github to read 9 axis data with TWI. But the example in TWI floder doesn't work.

Does somebody have the same issue?

Chip: nRF51422

Board: PCA10028

Firmware: S130_nRF51_2.0.1

I have checked the TWI pin define, SDA SCL voltage, and the code in mpu_init(). I found a lot of problems in that code. Does somebody have the same issue? Please make a response or even share the ideas with me.

update: I've checked that my module already has 10K pull-up for SDL and SDA. I have found the root cause, I should make SDO (ADO) to low for address 0x68 and SDO (ADO) to high for address 0x69. I still don't know what's the purpose of this design?

[dkwill]

The AD0 defines the address - low is 0x68 which is in the example code. Mine has to be wired to GND for it to work. Just FYI - I had difficulty getting some of the 3rd party MPU boards to work and had to make my own board. Anyway, I think the answer for you is likely on the hardware side.