There are two reasons for why I regreat bying this chip.
1) I was looking forward to get quarternions as an output, but from what i understand is impossible (I'm actually impressed that it is allowed to sell this chip under false pretenses).
2) The documentation on this chip/evaluation kit is poor and inadequate.
No documentation on the AK8975, and difficult to understand what some of the register acctually does.
well at least here's my problem:
I am using the MPU6050 EVK and I am trying to get the MPU to retreive data from the magnetometer AK8975 via the aux i2c master.
Why is there no documentation on this?.
If i set the MPU6050 in by pass mode i can read data from the chip, with the following sequence.
write 0x00 to register 0x0A in ak8975: low power mode
delay (100us)
write 0x01 to register 0x0A in ak8975: read mode
delay (100us)
read data starting from 0x03
If i use slave 0,1 and 2 i can create the same sequence.
slave 0 write 0x00 to register 0x0A in ak8975: low power mode
slave 1 write 0x01 to register 0x0A in ak8975: read mode
slave 2 read data starting from 0x03 (length 6 bytes)
BUT!! all 6 bytes are 0!!!
if i use my logic analyser on the aux. line i can see that the mpu6050 is writing and reading as expected, but without delays between writing and reading. In the datasheet it says that it is recommended a delay of at least 100us.
If i skip the dealys in bypass mode i get the same result as the MPU6050 gets.
Does this mean that it is impossible to get the MPU6050 to read data from the AK8975?, has anyone got this to work?.
If any of the this is not correct, prove me wrong!
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