defragster
Senior Member+
Teensy 4 Beta2 Mod tolerates powered UARTS on startup
ALL GOOD - First indications show T4B2mod able to power up and run without issue when 2 T_3.x UARTs powered and connected::
> USB power on connect
> Off/ON breakout button
> 15s Restore Button press
Just in from mail box, removed T4B2 from Breakout, installed T4B2mod onto Breakout - existing UART Tx&Rx Serial #2 and #4 connects in place to T_3.5 and T_3.1.
added Notes - T_3.x UARTS power in all cases [except 2(b)/(c)] - no vBat power applied:
1: The UART power glows the Breakout Green LED when breakout Power Button used to OFF, then cutting T4's USB power with switch the LED goes from GLOW to near half bright or Dim - don't recall that Glow/Dim difference - so assume the brownout change is diverting power to GND differently.
2(a): When breakout Power Button used to OFF - and power removed ( 5V from USB cut or Cable pulled ) - and then power is restored it maintains the OFF state until breakout Power Button used to ON - UART power maintains the state.
2(b): When breakout Power Button used to OFF - and power removed ( 5V from USB cut or Cable pulled ) - and T_3.x UARTS powered off - and then power is restored it returns in ON state.
2(c):: UART 3.3V [RE 2(a)] is keeping the part of the MCU alive that is recording ON/OFF power button state. The same when vBat is powered and UART and other power removed.
3: As expected the Teensy Button has no effect in either of the above cases
4: Power button on breakout works normally as expected
ALL GOOD - First indications show T4B2mod able to power up and run without issue when 2 T_3.x UARTs powered and connected::
> USB power on connect
> Off/ON breakout button
> 15s Restore Button press
Just in from mail box, removed T4B2 from Breakout, installed T4B2mod onto Breakout - existing UART Tx&Rx Serial #2 and #4 connects in place to T_3.5 and T_3.1.
added Notes - T_3.x UARTS power in all cases [except 2(b)/(c)] - no vBat power applied:
1: The UART power glows the Breakout Green LED when breakout Power Button used to OFF, then cutting T4's USB power with switch the LED goes from GLOW to near half bright or Dim - don't recall that Glow/Dim difference - so assume the brownout change is diverting power to GND differently.
2(a): When breakout Power Button used to OFF - and power removed ( 5V from USB cut or Cable pulled ) - and then power is restored it maintains the OFF state until breakout Power Button used to ON - UART power maintains the state.
2(b): When breakout Power Button used to OFF - and power removed ( 5V from USB cut or Cable pulled ) - and T_3.x UARTS powered off - and then power is restored it returns in ON state.
2(c):: UART 3.3V [RE 2(a)] is keeping the part of the MCU alive that is recording ON/OFF power button state. The same when vBat is powered and UART and other power removed.
3: As expected the Teensy Button has no effect in either of the above cases
4: Power button on breakout works normally as expected
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