Is there a wise way to debug a large code?

[richard]

I think, maybe this is RMW issue somehow?

not at all likely , which pin is having its expected digitally "read back" value changed by a digital write to another pin on the the same port ?

as ioannis suggests this is looks very much an EMI problem that could most likely could be ameliorated by having the switch circuitry of more suitable impedance and using appropriate adc conversion speed along with sample hold time and rate.


with no schematic or code to look at it might just be bad code who would know

[CuriousOne]

Ok, here is the part of code which reads the keys:

adcin 7,ard
if ard<130 then 'if any button is pressed
ticker=ticker+1 'increase value and wait - debouncing
pause 1
endif
if ticker>150 and ard<100 then  'if left button is pressed then next menu item
menuitem=menuitem+1
ticker=0 'reset debouncer
endif
if ticker>150 and ard<130 AND ARD>100 then  'if right button pressed, change the value
CVLADI=CVLADI+1
if cvladi>ulim or cvladi<dlim then cvladi=dlim
ticker=0

here is PCB

[richard]

Ok, here is the part of code which reads the keys:

pointless snippet . how is adc setup ?

good luck trying to use adc value without passing it through a lpf

a pic of blank pcb is not a schematic

[CuriousOne]

DEFINE ADC_BITS 8 ' Set number of bits in result
DEFINE ADC_CLOCK 3 ' Set clock source (rc = 3)
DEFINE ADC_SAMPLEUS 50 ' Set sampling time in microseconds

Here is ADC setup. All PBP defaults.

Unfortunately, I don't create schematics - I directly draw PCB, since I can read it in same way, as schematics

[richard]

Unfortunately, I don't create schematics - I directly draw PCB, since I can read it in same way, as schematics

that just explains so much
good luck with your endeavors i'm out

[CuriousOne]

Well, added 0.1uf capacitor at ADC input, so far, works fine.

[Ioannis]

This just shows that you have strong interference in the analog inputs because of EMI noise. Where it is coming from?

Well, you can read the PCB as schematics, so as Richard said, good luck here!

If you make a lot of ADC readings, say 20, and then sort them in order, through away the 5 first and last numbers, with the rest 10 make a mean number, then you may get rid off the 100nF capacitor and be more confident of the readings. This makes for a low pass filter in software.

Personally, NEVER use raw adc readings. This is just looking for troubles. A spike can ruin your day. Make many readings and get the best of them to be sure of noise free readings.

Ioannis