Muon M404 40 pin header dropping power pins

Hardware
1

I have two new M404’s in test. Everything is working as spec’d except the 40 pin header power. I used Particles web setup and also installed the STARTUP code recommended on this site. When I first boot the device I have both 3.3v and 5.0v power to the pins - after 30 to 60s the power to both output fades over a 2-3s interval at that point the 3.3v pins output 0.973v.

I traced the boot process and cannot locate a specific action that causes this. Anyone else seeing this behavior?

2

Hi, are you talking about the code mentioned in the link below?

Is your code changing d7 by any chance? From the link above as well:

To control 3V3_AUX manually from your firmware, use pinMode(D7, OUTPUT) in setup(). Use digitalWrite(D7, 1) to turn 3V3_AUX on and digitalWrite(D7, 0) to turn it off.

Best,

3

Yes, that is the code I added to my firmware.

I am not changing D7 but will test your feedback and report. What about the 40 pin 5v? It too is active at boot then when 3.3v drops so does 5v. I’ll look at GitHub maybe there is a pin mapped to that also.

4

Which STARTUP code are you using? That's not the recommended way to enable 3V3_AUX on the Muon.

You should use the firmware settings to enable 3V3_AUX, and this only needs to be done once. It also cannot be done from STARTUP, it should be done in setup().

// Enable 3V3_AUX
SystemPowerConfiguration powerConfig = System.getPowerConfiguration();
powerConfig.auxiliaryPowerControlPin(D7).interruptPin(A7);
System.setPowerConfiguration(powerConfig);
5

Thank you Rick. I am using the code you list but in STARTUP not setup. Will relocate it this morning a test.

6

Made the change, works perfect. Thank you both.

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