Hi -
I know that this topic has been covered before, but I can't get my Teensy 3.2 to boot except when it is powered via a computer USB port. More specifically, it won't even boot when powered by a USB battery source. It won't boot with 5V on Vin from my bench supply or 3.3V on the 3.3V line from my bench supply. It will only boot when the computer is powering it.
I am watching the VUSB, 3.3V, PROG, and reset lines on a scope and can see that the VUSB power comes up first (with slightly different response, depending on the power source), then the 3.3V starts coming up about 30 uSec later, then reset comes high 100 uSec after the 3.3V line gets above 2.45V or so. Prog comes high about 30uSec before reset. This consistently happens no matter the power source.
I tried the capacitor from ground to reset trick, and played with different capacitors, but no luck. In fact, I can't get reset to work even when I ground it if the power source is anything other than a computer port. Grounding reset works fine if it is powered from a computer.
Yes, I'm running a power up blink so I can see the LED come on and blink when it boots correctly.
No, the VUSB/Vin jumper is not cut.
I don't have any other devices attached.
Is the boot device able to keep the processor from running even if reset is high?
Boot from Computer USB - Teensy boots.
Boot from Large USB Battery Pack - No joy.
Boot from Small USB Battery Pack - No joy.
Green = Vin; Yellow = 3.3V Out; Pink = PROG; Blue = Reset (Test point on back of Teensy 3.2)
I know that this topic has been covered before, but I can't get my Teensy 3.2 to boot except when it is powered via a computer USB port. More specifically, it won't even boot when powered by a USB battery source. It won't boot with 5V on Vin from my bench supply or 3.3V on the 3.3V line from my bench supply. It will only boot when the computer is powering it.
I am watching the VUSB, 3.3V, PROG, and reset lines on a scope and can see that the VUSB power comes up first (with slightly different response, depending on the power source), then the 3.3V starts coming up about 30 uSec later, then reset comes high 100 uSec after the 3.3V line gets above 2.45V or so. Prog comes high about 30uSec before reset. This consistently happens no matter the power source.
I tried the capacitor from ground to reset trick, and played with different capacitors, but no luck. In fact, I can't get reset to work even when I ground it if the power source is anything other than a computer port. Grounding reset works fine if it is powered from a computer.
Yes, I'm running a power up blink so I can see the LED come on and blink when it boots correctly.
No, the VUSB/Vin jumper is not cut.
I don't have any other devices attached.
Is the boot device able to keep the processor from running even if reset is high?
Boot from Computer USB - Teensy boots.
Boot from Large USB Battery Pack - No joy.
Boot from Small USB Battery Pack - No joy.
Green = Vin; Yellow = 3.3V Out; Pink = PROG; Blue = Reset (Test point on back of Teensy 3.2)