Custom MicroMod board

toyosm

Well-known member
I made a couple of boards based on the MicroMod gerbers on Sparkfun site. After power up I have a 2 blink error from the bootloader stating "2 Blinks = NXP JTAG Not RespondingNo 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". I checked the power up sequence and everything is ok until step 8, where I have to see the 1.15v coming from the 1062. I checked all the voltages and components that I could check but everything seems fine. I can't get the 1.15v on L2 (attached the schematic for reference) that I got on a Sparkfun MicroMod which I'm comparing it with. The MKL02 is bought from PJRC, the DCDC_PSWITCH is high (that should enable the internal voltage of the 1062), the microcontroller I'm using is the MIMXRT1062DVL6B is the same as the MicroMod I have and the flash memory is also the same. To test both I'm using an ATP board carrier from Sparkfun to ensure that everything is ok and only testing what's happening on the module.

Any thoughts on what can it be or what else I can check?
 

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Can you monitor the startup with an oscilloscope? Trigger on DCDC_PSWITCH rising edge. You're looking for whatever activity happens on both sides of L2 after that rising edge. The DCDC switching is supposed to start up.
 
Can you monitor the startup with an oscilloscope? Trigger on DCDC_PSWITCH rising edge. You're looking for whatever activity happens on both sides of L2 after that rising edge. The DCDC switching is supposed to start up.
I have 0v on either side of L2, using the DCDC_PSWITCH as trigger
 
I can't imagine any explanation other than something isn't connected, such as L2 or the DCDC_PSWITCH signal.

The DCDC switcher inside the RT1062 chip is supposed to start up when it hears a rising edge on DCDC_PSWITCH. The rising edge is supposed to be transmitted only after 3.3V power has stabilized, so you might want to also capture the 3.3V power if your scope has another channel unused. But even if the 3.3V power isn't great, it will still try to start switching by delivering pulsed output from the DCDC_LP pins. You should see some sort of activity on L2.

The only plausible explanations I can imagine are the DCDC_PSWITCH rising edge isn't making to the RT1062 pin, or L2 isn't connected at all to the RT1062's 2 DCDC_LP pins.
 
Well, finally the problem was a manufacturing one... I made a batch of 5 pcb's, the first one that I grabbed is the only one of the batch that doesn't work!. Thanks for the answers, was an interesting testing
 
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