ATMega88PB calculating problem

nobner · Joined: 29 Apr 2015 Posts: 24

Hello to all,
i'm counting two PWM-Pulses (500Hz) into PinC.1 and PinC.2 of an ATMega88PB (10MHz Crystal).
Therefore i'm using Timer1 with a Prescaler of 8.
Data input:
Start Timer1
Timer1 = 0
while PinC.1 = 1
wend
value = Timer1

this measurement i'm doing 10 times in a loop to achieve higher value for calculation

the single value is always correct, but the value calculated after the loop is wrong in ONLY ONE POSITION OF PWM:
Stepping down in 1µs steps, it jumps at a value of 6300 about 200 digits to 6100. After that, counting is correct again (6100, 6090, 6080.....)
This means, that the 10 times counting loop is wrong on only this single position.
Stepping up, the same jump happens (6090, 6100, 6300, 6310, 6320...)
The PWM time at this issue is 630µs

NEW:
i had a serial display attached on PortE.3 to show these values. When i take the display programm out of the code, everything works fine... don't understand this, because counting loop is in a complete other programm section.

I would be thankful for any suggestion.

kind regards
Norbert

(BASCOM-AVR version : 2.0.8.1 )

Evert :-) · Joined: 18 Feb 2005 Posts: 2165

Without the rest of the code it's hard to help.
2 things regarding the code you posted.