It looks like I've killed my latest Teensy 3.2 (soldered to a Prop Shield LC) by accidentally swapping the +6V and GND from my batteries when testing the PCB boards I've had fabricated. The puzzling thing is the Teensy appeared to be working for a while after this initial mishap, but died an hour later during subsequent testing. The Teensy is no longer recognized as a USB device, and I get an error message from my Mac OS when I hook it up (something like the USB device is drawing too much power).
Is it possible to damage a Teensy in such a way that it can withstand a few power cycles before dying, or should I be looking for some other culprit in my circuitry?
This is a breadboarded version of the circuit I've been working on forever:
I taught myself KiCad and had these boards fabricated by OSHPark (note the components shown have just been placed temporarily into the board):
Last night I went about soldering in the Teensy 3.2/Prop Shield LC, the voltage regulator, some PicoBlade connectors, the transistors I'm using for the touchswitches, and their associated resistors. I wanted to solder in a minimal amount of components to see if the thing powered up and whether the touchswitches were working.
I'm using this voltage regulator to step down the 6.2V from my batteries to 5V:
https://www.pololu.com/product/2836
Unfortunately, I misread my schematic and swapped the + and - leads from my battery to the PicoBlade connector through which the 6.2V runs to the voltage regulator. When I switched on the batteries I saw a flash of grey haze appear next to the regulator and a burning smell. Idiot. I removed the regulator and tested it on the breadboard, It appeared to still be working, so I soldered it back onto the PCB board via some jumpers. Upon troubleshooting I found that the trace that ran from the 6.2V pin of the PicoBlade to the input of the voltage regulator appeared to have broken; I no longer get continuity when I test those contacts.
To troubleshoot further I hooked my batteries directly up to the regulator (with the correct polarity), bypassing the PicoBlade connector. The touchswitches now worked as designed, sending the servos to their proper positions (I'd yet to hook up any LEDs). The audio, however, wasn't working. I was just getting static or a squeal when the servos moved. I'm guessing I fried my Prop Shield during the initial polarity screwup.
As a test I then tried jumping the broken trace by soldering a small wire between the 6V input pin on the PicoBlade to the input of the regulator. I switched on the batteries, heard the servos briefly move to reestablish their "home" position (as they usually do), then nothing (except maybe a slight burning smell). I disconnected everything I could and attempted to upload the Blink sketch to the Teensy, but no go. USB isn't seeing it.
So is it possible I damaged the Teensy on the initial polarity screwup enough to injure but not kill it, but then it died completely after a few more power cycles? There's a very slight possibility that a bare input wire touched an LED output wire from one of the harnesses. I have no idea whether such an event would fry the whole Teensy.
This is the second Teensy 3.2 I've bricked in the past few months, and I think both were due to me screwing up the battery power. The first happened during the breadboarding stage while moving jumpers. My subsequent breadboard (with a new Teensy and Prop Shield), as shown in the video, performed perfectly.
I'm not what you would call an electronics expert, so any insight from experienced engineers or designers would be greatly appreciated. If it would help I could post my schematics.
Thanks.
Shawn Marshall
Is it possible to damage a Teensy in such a way that it can withstand a few power cycles before dying, or should I be looking for some other culprit in my circuitry?
This is a breadboarded version of the circuit I've been working on forever:
I taught myself KiCad and had these boards fabricated by OSHPark (note the components shown have just been placed temporarily into the board):
Last night I went about soldering in the Teensy 3.2/Prop Shield LC, the voltage regulator, some PicoBlade connectors, the transistors I'm using for the touchswitches, and their associated resistors. I wanted to solder in a minimal amount of components to see if the thing powered up and whether the touchswitches were working.
I'm using this voltage regulator to step down the 6.2V from my batteries to 5V:
https://www.pololu.com/product/2836
Unfortunately, I misread my schematic and swapped the + and - leads from my battery to the PicoBlade connector through which the 6.2V runs to the voltage regulator. When I switched on the batteries I saw a flash of grey haze appear next to the regulator and a burning smell. Idiot. I removed the regulator and tested it on the breadboard, It appeared to still be working, so I soldered it back onto the PCB board via some jumpers. Upon troubleshooting I found that the trace that ran from the 6.2V pin of the PicoBlade to the input of the voltage regulator appeared to have broken; I no longer get continuity when I test those contacts.
To troubleshoot further I hooked my batteries directly up to the regulator (with the correct polarity), bypassing the PicoBlade connector. The touchswitches now worked as designed, sending the servos to their proper positions (I'd yet to hook up any LEDs). The audio, however, wasn't working. I was just getting static or a squeal when the servos moved. I'm guessing I fried my Prop Shield during the initial polarity screwup.
As a test I then tried jumping the broken trace by soldering a small wire between the 6V input pin on the PicoBlade to the input of the regulator. I switched on the batteries, heard the servos briefly move to reestablish their "home" position (as they usually do), then nothing (except maybe a slight burning smell). I disconnected everything I could and attempted to upload the Blink sketch to the Teensy, but no go. USB isn't seeing it.
So is it possible I damaged the Teensy on the initial polarity screwup enough to injure but not kill it, but then it died completely after a few more power cycles? There's a very slight possibility that a bare input wire touched an LED output wire from one of the harnesses. I have no idea whether such an event would fry the whole Teensy.
This is the second Teensy 3.2 I've bricked in the past few months, and I think both were due to me screwing up the battery power. The first happened during the breadboarding stage while moving jumpers. My subsequent breadboard (with a new Teensy and Prop Shield), as shown in the video, performed perfectly.
I'm not what you would call an electronics expert, so any insight from experienced engineers or designers would be greatly appreciated. If it would help I could post my schematics.
Thanks.
Shawn Marshall
