Boron Charge Fault Question

So recently I managed to turn off charging on my Boron 2G/3G device which works well. However, when running the Boron I notice the charging LED blinking slowly which indicates a charge fault. The LED does not start blinking immediately, only after a few mins of operation (~20mins+). This does not seem to affect the operation of the device whatsoever so I am just curious and have some questions:

  • With charging disabled and nothing connected to the LiPo port, how is a charge fault triggered? Re-enabling charging seems to stop the LED from blinking.
  • Anyway to nicely turn off this LED? I guess I could clear the fault and stop the LED from blinking?
  • I have not printed out the fault registers value and since it doesn’t seem to affect operation, its on my TODO backlog. Are the following values for the electron applicable/accurate for the Boron?

Charge fault values:

//Fault Register
//NOTE: This is a read-only register
					1: watchdog timer expired
6: Reserved
--- Charge fault status
5: CHRG_FAULT[1]	| 00: Normal, 01: Input fault (VBUS OVP or VBAT < VBUS < 3.8 V)
4: CHRG_FAULT[0]	| 10: Thermal shutdown, 11: charge safetly timer expiration
--- Battery fault status
3: BAT_FAULT		0: Normal
					1: BATOVP battery over threshold
--- NTC thermistor fault status
2: NTC_FAULT[2]		| 000: Normal
1: NTC_FAULT[1]		| 101: Cold
0: NTC_FAULT[0]		| 110: Hot

Set up

  • Boron 2G/3G on DeviceOS 0.9.0
  • USB powered with 5V, 2.4A

Relevent Docs

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@ParticleD, or @mstanley are you able to assist?

The problem is most likely the charge safety timer. It must be disabled as well as disabling charging, otherwise the charge fault light will come on at some point in the future.

This post is for the Electron and E series, but the Boron uses the same PMIC and I think it should work the same on the Boron 2G/3G.

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@rickkas7 thanks!

I tried this on my Boron unit and ran into some issues. Fire I assume Wire3 is replaced with Wire? It seems that “Wire3” isnt defined for Boron. After added the Write.write() it seems my Boron gets stuck on breathing white. I guess it gets stuck somewhere and doesn’t reach Particle.connect(). Removing the Wire.write() reverts the issue.

void setup() {
  // Disable charging
    PMIC pmic;
    // 0b11001110 = disable watchdog
    // 0b11000110 = disable watchdog and charge safety timer
    byte DATA = pmic.readChargeTermRegister();
    DATA &= 0b11000110;
    // This would be easier if pmic.writeRegister wasn't private (or disable
    // charge safety timer had an exposed method

  // Set up cellular connection
  	Particle.keepAlive(gKeepAlive); // This is needed if we are using Roger's network
    Particle.connect(); // Make sure connect is alway last since we want to register all cloud components first
    cellular_credentials_set(gCellularAPN, "", "", NULL);

The block diagram in the Boron datasheets shows this

and these are not the Wire pins.

But you may want to try Wire1 instead.

Sorry, yes, it should be Wire1 on the Boron, not Wire3.

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