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Issue with serial communication

Posted: 04 Mar 2019, 03:07
by theMainframer
My Gigatron has an issue where the left arrow does not work on both the controller and the keyboard. Also, when I tested the keyboard many of the keys did not output their corresponding letter and some were even duplicates (I have two keys that output '7' for example). I checked for bad soldering, but I did not see any obvious problems. What are your opinions for what could be causing this?

Re: Issue with serial communication

Posted: 04 Mar 2019, 10:01
by marcelk
This would be the connection of the shift register U39 pin 1 to the data bus. It can be checked with a multimeter. For example verify that this pin makes a connection to U10 pin 9.

74HC595.jpeg
Game controller buttons to bus
74HC595.jpeg (270.47 KiB) Viewed 315 times

Re: Issue with serial communication

Posted: 05 Mar 2019, 21:55
by theMainframer
Thank you, that solved the problem.