Boron VIN solar charger problem with firmware 1.4.2

Troubleshooting
8

I’d like to give everyone affected by this change an update on:

  • Why this change was made
  • The unintended side effect
  • The workaround
  • Our choices now
  • Some input needed

  1. This initial change was made so that it is possible to utilize the Boron without using a LiPo battery enabling 1500ma of current to be drawn from VIN. The fact that it did not already do so was a bug as the USB was incorrectly detected whether powered from USB or not therefore limiting current to 500ma.

  2. The unintended side effect is that devices without current draw protection at this level could be damaged. Current-limited devices would not be affected.

  3. This workaround disables the interrupt for LOW_BAT_UC so that the system does not reset the limit and enables the user to set a new limit.

void setup() {
    detachInterrupt(LOW_BAT_UC);
    // Delay for up to two system power manager loop invocations
    delay(2000);
    // Change PMIC settings
    PMIC pmic;
    pmic.setInputVoltageLimit(4640);
}

This might be needed to be executed after waking from STOP mode sleep as well.

  1. The simplest thing we can do now is to reset the limit back to 500ma by default. However, that introduces an incompatibility with the Electron which has a default charging current of 900ma. Therefore the reset should really be 900ma while providing an ability to set a larger charging current to avoid having to use a LiPo battery.

  2. We would like to know whether the 900ma default would still cause the problems that you have. If that current resolves the problem we’ll set the default the same as the Electron and provide a mechanism to increase it to 1500ma.

We are sorry that anyone has been impacted by the change and appreciate your input in helping us to get the right result going forward.

Thanks, Ian.

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