Rigid-Flex Custom Teensy 3.2 not loading the firmware

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ElkinDiaz

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Dear PJRC Community,

We have a prototype project that require a rigid flex PCB design. It implies a custom Teensy 3.2 board. We have already some experience with rigid Custom Teensy 3.2 with success in two previous projects.

Our first units are not loading the firmware, we have been investigating about the problem, and particularly have been checking the different ideas found on:
https://www.pjrc.com/store/ic_mkl02.html


Items we have checked:
• VBAT is connected with the external 3.3V supply.
• VREGOUT is connected with the 3.3V supply trough a BAT54C diode.
• Pin 33 PTA4 is floating
• D+ and D- are not swapped
• Differential Pair was certified and measured by PCB manufacturer at 85 ohms.
• PROGRAM signal when the pushbutton is not pressed is at: 3.289V
• RESET signal while holding the pushbutton down is: 0.002V

I have measured the signal on MK20 RESETB using the oscilloscope:

waveform_2.png

waveform_1.png

Here I attach the schematics and layouts of the project, please check the attached file "STX_Rigid_Flex_Design.pdf". While the PCB Stack is rigid-flex, the Teensy 3.2 components are all located in a rigid part, the flexible parts are only used for buses.

Can you please give an advice or idea on things we might also review? In the meanwhile we will continue looking for the issue and double-checking everything.

Thanks,
 

Attachments

  • Schematics.pdf
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  • Schematics_Battery.pdf
    111 KB · Views: 68
  • Schematics_BLE.pdf
    107.9 KB · Views: 56
  • Schematics_IMU.pdf
    107.1 KB · Views: 69
  • STX_Rigid_Flex_Design.pdf
    556.6 KB · Views: 74
Last edited:
Dear PJRC Community,

I have find the issue it was a bad placement of one component in the assembly, please delete this thread.

Thanks,
 
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