Forums - I2C with Accelerometer on CSR8670

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I2C with Accelerometer on CSR8670
Join Date: 22 Nov 16
Posts: 2
Posted: Tue, 2016-11-22 08:49

I'm sorry if this is the wrong forum, but I could not find one designated specifically for the CSR8670.

I am attempting to connect an IMU sensor (the MPU6050 on a GY-521 breakout board) to the CSR8670 on a BC127 discovery board. Using the PSTool application in the ADK4.0.1 package, I set the PSKEYs I2C_SCL_PIO to 0x0007 and I2C_SDA_PIO to 0x0006. With an oscilloscope, I can see activity on both lines at three different voltage levels (0, ~1.8, and 3.3V). When I attempt to write or read from the device registers, it fails. Here are some excerpts from the code:


#include <message.h> 
#include <stdlib.h> 
#include <i2c.h> 
#include <panic.h> 

#define I2C_DEVICE_ADDRESS     0x68 //presumably, this is supposed to be the i2c address on the MPU6050 
#define I2C_A_DEVICE_REGISTER  0x6B //this is the power management register, used to wake the device from sleep

int main(void){
    uint8 data = 0;
    uint8 i2c_data[2];
    i2c_data[0] = I2C_A_DEVICE_REGISTER;
    i2c_data[1] = data;
    PanicZero(I2cTransfer(I2C_DEVICE_ADDRESS, i2c_data, 2, NULL, 0)); //this is where the error occurs - I2cTransfer returns 0, which means that 0 bytes were successfully transferred


The exact error message printed to the console is "VM has panicked! Reason: Pointer is NULL (Context: 0x0)."

What am I doing wrong with regard to setup? Other than setting the PS Keys, are there any prerequisites for using the PIO pins for I2C?


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Join Date: 31 Jan 17
Posts: 2
Posted: Tue, 2017-01-31 01:24
*/ */

Can you try this

PanicZero(I2cTransfer(I2C_DEVICE_ADDRESS<<1, i2c_data, 2, NULL, 0))





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