The Problem:
When powered from USB (PC or wall adapter) LED always turns ON.
When powered from my PCB, sometimes the LED doesn't turn on. It seems that if LED doesn't turn on, successive power cycles (4-5) will eventually make the LED turn ON. Once ON, if power is cycled with short dead times, the LED will come on every time. However, if I power it OFF and wait, I'm back to first case where it might not turn ON.
Things I've tried:
- Use a delay (1000) at beginning of program,
- Ensured the issue is repeatable with simple "turn built in LED ON" program (No waiting for serial or peripherals)
- Set USB type to "No USB"
- Temporarily added a 5V regulator (center of picture) on PCB, removed the 3.3V pin on teensy and supped power to the Vin pin instead. (asumed my 3.3V source was not good)
Any idea what's causing this?
PCB has built in 3.3V voltage regulator and Normally powers the Teensy directly on the 3.3V pin. In the following picture a 5V regulator was added to supply power on Vin pin.
When powered from USB (PC or wall adapter) LED always turns ON.
When powered from my PCB, sometimes the LED doesn't turn on. It seems that if LED doesn't turn on, successive power cycles (4-5) will eventually make the LED turn ON. Once ON, if power is cycled with short dead times, the LED will come on every time. However, if I power it OFF and wait, I'm back to first case where it might not turn ON.
Things I've tried:
- Use a delay (1000) at beginning of program,
- Ensured the issue is repeatable with simple "turn built in LED ON" program (No waiting for serial or peripherals)
- Set USB type to "No USB"
- Temporarily added a 5V regulator (center of picture) on PCB, removed the 3.3V pin on teensy and supped power to the Vin pin instead. (asumed my 3.3V source was not good)
Any idea what's causing this?
Code:
void setup() {
pinMode(13, OUTPUT);
}
void loop() {
digitalWrite(13, 1);
}
PCB has built in 3.3V voltage regulator and Normally powers the Teensy directly on the 3.3V pin. In the following picture a 5V regulator was added to supply power on Vin pin.