Teensy 4.0 Blink Twice Issue

Hello!

I have a Teensy 4.0 and whenever I plug in the usb b adapter into the port the red LED constantly blinks twice instead of the orange light turning on.

I believe that the red LED blinking twice is an error code signaling that there is a problem regarding between the MKL02 and IMXRT chip, which I don't know how to resolve.

The only modifications I have done to the teensy are that I have soldered pins onto it. I have also tried multiple USB cables to plug my teensy into different computers (including ones that used to work with my previous teensies) and I have had no luck removing this error.

Does anyone have any ideas on how I can resolve this issue?

Thank you!
 
So the T_4.0 powered up to Blink Orange from New before pin ssoldering?

This page: www.pjrc.com/store/ic_mkl02_t4.html

Gives this not ( for DIY boards ) that would suggest the expected reason for seeing that 'dual RED blink"
Code:
2 Blinks = NXP JTAG Not Responding
No communication is working! The 2 likely causes for this problem are improper power startup sequence, or a problem with any of these connections between the MKL02 and IMXRT chip:

Perhaps a close examine or good photos will show some short or soldering issue that might be affecting the power up process. Either s short to the pin soldering or a splatter blob of solder or rosin somewhere it should not have gone.

Also perhaps compare the board in hand to the posted T_4.0 images: pjrc.com/store/teensy40.html
To make sure each of the expected components is in place.
 
Sorry, probably a long shot.

But one of the first things I would try, would be to: power it up and then hold the program button down for maybe 15-30 seconds and see if you get a single like blink and then release the button. Hopefully you do and it reprograms the Teensy back to the ship program and it works again.
 
Hello! Thanks for helping me out!

I forgot to mention that the teensy is soldered to another circuit board, so I won't be able to take out the pins and inspect it. I have however tested each pin and every adjacent pin with a multimeter to see if there are any shorts through multimeter, but unfortunately I haven't found any shorts or anything.

Is there anything else I can try attempting?
 
Hello! Thanks for helping me out!

Yeah I have tried holding the program button for like a minute or so but it doesn't seem to stop the blinking twice error code. It doesn't seem to be detected by my PC either so I don't think its a code problem or anything like that.

is there anything else I can try?
 
Was going to suggest 15sec Restore next - but figured if it was an electron/power issue that wouldn't work so other steps were first.

What is on the PCB it is soldered to?

Did the visual inspection show anything? No adjacent pin bridging is a good sign - but something is affecting power up and apparently not a USB cable or incoming USB power with multiple tested. A sputtering bit of solder could be sitting in a bad place making a connection.

As attached to another, can't see the bottom side - but top side only soldering to pins shouldn't have changed anything below.

Is this the only T_4.0 on hand? If another is there, seeing the computer and cable connect to upload to that would assure the problem is just that now soldered T_4.0.

Tough to debug ... do VIN and 3.3V pins show the right voltage, Nothing hot to touch? A meter in line with 5V supply to measure Current draw might show if something is odd - but the startup timing window is very short.
 
What is on the PCB it is soldered to?


Hello!

It's soldered onto a phob 1.23 pcb board (it's a custom pcb for the Nintendo Gamecube Controller). The layout looks something like this: image_2022-08-30_000932518.png

Is this the only T_4.0 on hand? If another is there, seeing the computer and cable connect to upload to that would assure the problem is just that now soldered T_4.0.

I actually have another teensy 4.0 attached to a phob pcb with the exact same problem. I also have another teensy attached to another phob 1.23 pcb board which actually works. On that one I can upload code just fine on it (so the project does actually work)

Tough to debug ... do VIN and 3.3V pins show the right voltage, Nothing hot to touch?

Hm it appears when I try this I get about 1.03 volts. Is this a problem?

A meter in line with 5V supply to measure Current draw might show if something is odd - but the startup timing window is very short.

I'm not exactly sure how to test this (I'm slightly new to this soldering and testing electronics stuff), which pins do I put my multimeter on to test this?
 

Attachments

  • image_2022-08-30_000817925.png
    image_2022-08-30_000817925.png
    96.6 KB · Views: 15
Yes, 1.03 V (on 3.3V pins?) would be signs of a problem.

Measuring current takes putting a multimeter properly set and probes connected then put inline with incoming voltage - which requires breaking out the USB cable with an adapter or a cable split open with power line cut and meter probe tips completing the circuit. Not sure what it would show - as the 1.03 V indicates some problem, that I'm not equipped to diagnose.
 
Ohh so from what I'm getting, measure the current between the USB A end and the USB B end? If that's the case, what type of current should I be expecting?

Also as for the 1.03V on the 3.3V pins, could that be caused by a short somewhere?
 
No pretense of EE details assumed or implied ...

Yes, current measure in a line passing all the electrons. Meter inserted in a cut in the line to complete the circuit through the meter. Can be + or -/GND path. T_4.0 typical maybe 80-100 mA? Test it with the working one if you do that test.

A short or some ruined component it would seem. Earlier post asked about a hot component? Seems eating ~2.2V would get hot, unless something got fried and it just isn't working right to make the 3.3V, and not drawing the expected current.
 
Back
Top