S32K146 debug_Couldnot connect to the target

[ankan_creatara]

Greetings all,

We are designing a vehicle control unit using the S32K146 microcontroller. We have designed the schematic and PCB boards and have initiated the project with the first sample testing of 5 boards. 

The process adopted in developing and assembling of the boards are identical for all the 5 samples. To our surprise, 2 of the boards are working perfectly fine (i.e. codes are successfully flashed, all the GPIO pins are working as intended). However, there are issues with the remaining 3 boards. The issues are as follows:

1. In one board, the code is flashed successfully, however, the VCU board is not performing as intended (i.e. the GPIO pins are not working). On trying to debug the board using the S32K Design Studio IDE (using breakpoints in the code), its not hitting the breakpoints and it seems it is stuck in an infinite loop. 

2. In the remaining 2 boards, on trying to flash the code, there is an error which summarizes to "Could not connect to target ". 

I have tried my best to figure out the issue; but I am not being able to identify the same. Also, since the process adopted in developing the boards are exactly same (using the same Gerber and components from the same batch), I could not understand, why these 3 boards are behaving abnormally. 

Please help. 

P.S. If anyone had ever faced this issue and had resolved it. Please help me identify and rectify the boards. 

[Robin_Shen]

Hi

Please check the Figure 11. JTAG/SWD signal connections of AN5426, make sure the circuit is correct. Reset of MCU must be connected to debug interface.

The section 2 Power system of AN5426 mentioned:
1. All VDD and VDDA pins must be shorted and connected externally together to a common reference on the PCB. A decoupling capacitor must be used per each supply pin and a local Bulk/bypass capacitor just for the VDD and VDDA domains.
2. VREFH must be equal or less than VDD and VDDA.
3. VSS and VREFL must be shorted to GND at package level.

Which debugger are you using? PEMicro Multilink or Segger J-Link? Try a different debugger.

Best Regards,
Robin
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