Skip to content
New issue

Have a question about this project? Sign up for a free GitHub account to open an issue and contact its maintainers and the community.

By clicking “Sign up for GitHub”, you agree to our terms of service and privacy statement. We’ll occasionally send you account related emails.

Already on GitHub? Sign in to your account

MCP_INT is push-pull on boot - expected open-drain, needs a PNP transistor in series #63

Closed
CRImier opened this issue Aug 9, 2018 · 1 comment

Comments

Projects
None yet
1 participant
@CRImier
Copy link
Contributor

commented Aug 9, 2018

MCP23017, unexpectedly, has the INT pins in the push-pull mode on boot (at least it's still active low). This interferes with HAT EEPROM detection by Pi Zero, since it expects the GPIO0 to not be driven and instead pulled up to VCC. So, we need to add this solution between MCP23017 and Pi Zero/EEPROM:


Draft1.asc.txt

This also means we need to add a jellybean PNP transistor to the BOM. This is a suitable solution by now, but I'll look into whether we have a way around it.

@CRImier

This comment has been minimized.

Copy link
Contributor Author

commented Aug 9, 2018

Done!

@CRImier CRImier closed this Aug 9, 2018

CRImier added a commit that referenced this issue Aug 9, 2018

Sign up for free to join this conversation on GitHub. Already have an account? Sign in to comment
You can’t perform that action at this time.