10 years, 7 months ago.

Question about I2C library

Hello,

I use these codes on nRF51822:(section)

I2C mpu(P0_22,P0_20);

int main()

{

char cdd[2]={PWR_MGMT_1,0x03};

mpu.frequency(100000);

while(1)

{

mpu.start();

mpu.write((0x68<<1));

mpu.write(PWR_MGMT_1); register address: 0x6B

mpu.write(0x01);

mpu.stop();

wait(0.5);

mpu.start();

mpu.write((0x68<<1));

mpu.write(ACCEL_XOUT_H); register address: 0x3B

mpu.start();

mpu.write((0x68<<1)|1);

mpu.read(0); no ack

mpu.stop();

wait(0.5);

}

}

But something wrong with these codes. I use the logical analyzer to capture the wave. See as follows:

Write wave:

This wave is very good and follow my code.

But read wave:

My code just want to read a byte and answer a no-ack. But actually, it gives me two bytes and appear a ack.

Some bugs with the I2C library base on nRF51822? I used the MPU6050 library based on the I2C library, but I have no correct readings. Same phenomenon, more bytes more than my code gives.

Please help me.Thank you!

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Last updated: 27 Aug 2020

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