Copying variables

[iQd]

Hi,

I have a strange issue.
I am reading values from an accelerometer.
The read values go into an array which is uint8 and 7 bytes long.

The values are read ok and they exist in the array.
When I try to move the individual values to regular uint8 variables - nothing happens. The result is zero, even if the corresponding array index has a value.

I made a test and added a delay between each line.
Now, the values get copied normally from the array to the variables.

Can someone explain why this happens, why the 52832 does not perform these lines normally without delays in between?

This does NOT work:

      Accelerometer_X_L = SPI_rx_data[1];
      Accelerometer_X_H = SPI_rx_data[2];
      Accelerometer_Y_L = SPI_rx_data[3];
      Accelerometer_Y_H = SPI_rx_data[4];
      Accelerometer_Z_L = SPI_rx_data[5];
      Accelerometer_Z_H = SPI_rx_data[6];

All Accelerometer_X/Y/Z variables remain zero when the SPI_rx_data array has values on every byte.

The following DOES work:

      Accelerometer_X_L = SPI_rx_data[1];
      nrf_delay_us(50);
      Accelerometer_X_H = SPI_rx_data[2];
      nrf_delay_us(50);
      Accelerometer_Y_L = SPI_rx_data[3];
      nrf_delay_us(50);
      Accelerometer_Y_H = SPI_rx_data[4];
      nrf_delay_us(50);
      Accelerometer_Z_L = SPI_rx_data[5];
      nrf_delay_us(50);
      Accelerometer_Z_H = SPI_rx_data[6];
      nrf_delay_us(50);

Now the Accelerometer_,,, variables receive the values from each array index as expected.

How is this even possible?
It cannot be that the processor will not do as the code says.

Thank you!

[iQd]

I tested how low I can go with the delays and still get values copied ok.

It seems that 5 us is the limit between working code and non-working code.

If I set the delay to 2 us, only one or two variable values are copied.
Delay of 3 us will make all but the first two variables copied ok.
Delay of 4 us will make only the two last array indexes copied ok.

When the delay is 5 us, all values are copied ok and the code actually works.

I have never seen an issue like this, I lose valuable time with this kind of problems that should not even exist. 
This is not even the first time this happens with the 52832, I am starting to lose trust in the 52832.

I had earlier a similar issue where, at startup I set a variable to a certain value, nothing else touches this variable until the main loop.
Then, at the main loop when I check the value, the variable is somehow changed to a different value.
I was able to go around this only by setting the variable to the value I want, two times right before the main loop.

I am using the Nordic DK board, Segger v3.40 in Windows 7 x64, GNU ARM Embedded Toolchain version 7-2017-q4-major.