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ATMega32U4 Strange Looking Clock and MOSI Signals when doing ISP
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Topic: ATMega32U4 Strange Looking Clock and MOSI Signals when doing ISP (Read 1168 times)
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bendras
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ATMega32U4 Strange Looking Clock and MOSI Signals when doing ISP
«
on:
June 02, 2018, 12:04:34 pm »
I am seeing strange signals when trying to program ATMega32U4 with an ISP programmer (
https://www.sparkfun.com/products/9825
to be more precise).
Anybody has any ideas on what might be causing such a stepped signal?
If I measure the clock signal which comes out of the ISP when its not connected to the ATMega32U4 board then it looks correct:
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Rerouter
Super Contributor
Posts: 4700
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Question Everything... Except This Statement
Re: ATMega32U4 Strange Looking Clock and MOSI Signals when doing ISP
«
Reply #1 on:
June 02, 2018, 12:19:20 pm »
Its defiantly not transmission line effects, At a guess its a contested pin, What else connects to that pin on your circuit?
E.g. one device is pulling or driving high, and the other is trying to drive low.
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Gibson486
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Re: ATMega32U4 Strange Looking Clock and MOSI Signals when doing ISP
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Reply #2 on:
June 02, 2018, 02:22:08 pm »
Looks like you have another output or input pulling it down
One cause could be multiple push pull outputs on the same line.
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bendras
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Re: ATMega32U4 Strange Looking Clock and MOSI Signals when doing ISP
«
Reply #3 on:
June 02, 2018, 03:54:06 pm »
Thank you for the tips
. It turned out that the MOSI and CLOCK pins on the ATMega32U4 IC where accidentally shorted while soldering
. After removing the solder bridge everything works as expected.
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