HW Bug: R3 on REB Rev C causes Low Battery Detection to never work #35

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opened 2023-09-19 21:43:12 -03:00 by ZAdamMac · 1 comment
ZAdamMac commented 2023-09-19 21:43:12 -03:00 (Migrated from github.com)

The position of Resistor R3 is wrong, and worse, the resistor itself is superfluous.

Because it stands between the Low Battery (LBO) pin on the TPS module and the matched GPIO pin on the microcontroller, the line is constantly pulled high to the level of the main 3.3v rail; that is, the low battery signal is never sent.

By removing this resistor the issue is resolved in f/power-management-enhance's recent commits; using the internal pullup resistor on the MSP430 more than suffices.

Users of revision C development kits should cut resistor R3 off the board or otherwise remove it. TODO: remove from revision D before committing the schematics.

The position of Resistor R3 is wrong, and worse, the resistor itself is superfluous. Because it stands between the Low Battery (LBO) pin on the TPS module and the matched GPIO pin on the microcontroller, the line is constantly pulled high to the level of the main 3.3v rail; that is, the low battery signal is never sent. By removing this resistor the issue is resolved in f/power-management-enhance's recent commits; using the internal pullup resistor on the MSP430 more than suffices. Users of revision C development kits should cut resistor R3 off the board or otherwise remove it. TODO: remove from revision D before committing the schematics.
ZAdamMac commented 2023-09-19 21:45:50 -03:00 (Migrated from github.com)

Fix for this will be included on the Revision D schematics.

Fix for this will be included on the Revision D schematics.
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zadammac/PETI#35
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