Help to find bug in atmega 16 code

Hi
I hope someone can help me to find the bug(s) in my code (Atmel Atmega16). I have tried to debug the code, but could not get the debugger in AVR studio4 to work properly.
I have tested and know that the interrupt and the reading from the ADC works as expected, but after this I have at least one bug.

there is an error in


Alex

---------- Post added at 21:34 ---------- Previous post was at 21:05 ----------

I also see this

but PORTC is not changed to output anywhere in your code,
and you use it to send the result
you should add

Alex

Tnx for replay Alex

I did the change that you suggested, and downloaded the code to the target. I am still getting strange outputs at the atmega16.
The out value is much to high. I did a test and removed some of the code and just outputted the read ADC value at the outputs. I am still getting a to high digital value at the out ports, the strange is when I attach a load (LED and a resistance) to some of the c-ports, the voltage drops to 1,5V from the measured 3.2V (Vcc=3.2V). This is not the case for the ports PC0,PC1, and all of the B-ports, which is staying at 3.2V.
I did another test and outputted the high ADC value at the PORTB, and this was ok, but I am still measuring 3,2V at some of the c-ports without writing to the PORTC register.
I have tested the code with three different atmega targets and all of this gives the same results.

Code test1:
ISR(ADC_vect)
:
:
adc_data = ADCW ;
PORTB = adc_data;
PORTC = adc_data>>8;

Code test2:
ISR(ADC_vect)
:
:
adc_data = ADCW ;
PORTB = adc_data>>8;

Do you have any idea of where my fault could be?

The acos function is described like this

The acos() function computes the principal value of the arc cosine of __x. The returned value is in the range [0, pi] radians. A domain error occurs for arguments notin the range [-1, +1].

Click to expand...

I think you are using values that are out of this range.
for example with ADC result 256,
0.002429*256=0.621824
1.586/0.621824 =2.550

Also check that you have added the libm.a to the project.

Alex

alexan_e said:

The acos function is described like this



I think you are using values that are out of this range.
for example with ADC result 256,
0.002429*256=0.621824
1.586/0.621824 =2.550

Also check that you have added the libm.a to the project.

Alex

Click to expand...

Hi
To avoid the size problem you mention, I am using the If-statement to check the size of the in value.
Could the problem be that I am reading a 10bit value from the ADCW(ADCL+ADCH) into a 16 bit integer value. The ADCH register uses only the two lowest bits (if right adjusted). I am reading all eight from this register and expect the six highest bits to be zero all the time, but are these bit really zero? maybe they are undefined and this is the reason for my troubles.
How do I check that the libm.a is added to the project?

in AVRSstudio, go to Project -> Configuration Options ->setup dialog. Then go to the Libraries button down the side, and you can select libm.a to be used.

Alex

---------- Post added at 16:29 ---------- Previous post was at 16:25 ----------

The 16bit integer isn't the problem but if you want you can use (ADCW & 0x3ff)

Alex

for anyone reading this thread, the solution is described in a similar thread
https://www.edaboard.com/threads/206873/#post875005

Alex