Issues with Custom Board using iMXRT1062 Chip - Page 1
Forum section: electronics / beginners

author: SamS
author_rank: Newbie
timestamp: May 14, 2024, 04:29:03 pm
content: Hello All,I've attempted to make my own board using the MIMXRT1062CVJ5B. This is my first experience in the electronics world and my first attempts at hardware design (KiCad), software design (MBDT in Simulink) and debugging (MCUXpresso with MCU-Link). I've been stuck on this issue for months and would appreciate any help.When using the SDK-Examples with the MIMXRT1060-EVKB, they work without issue (iled Blinky + Hello World). When using my board and flashing over SWD in MCUXpresso, iBlinky appears to stop when trying to do something with the EnetPLL:And Hello World generates a Hardfault, but also has issues, I believe, during the Clock EnablingBut I can write my own code using MBDT in Simulink and flash over SWD to generate a flashing LED and it works, the LED will flash but at times it has memory access issues when looking at "Disassembly".This is all with the device in "Internal Boot" with BOOT_MODE_0 pulled low and BOOT_MODE_1 pulled high. The board has USB and UART and I'd like to use "Serial Downloader". When I set the device to "Serial Downloader" (BOOT_MODE_0 pulled high and BOOT_MODE_1 pulled low), the LED will stop blinking but the device can't been detected by MCUBootUtility or SecureProvisioningTool (either with UART or USB).From all of this, I believe I have a hardware issue and my best guess is that I have an issue with clocks, specifically the XTAL 24MHz.I'm using the NX3225GA-24MHZ-STD-CRG-2 (https://datasheet.lcsc.com/lcsc/1810171130_NDK-NX3225GA-24MHZ-STD-CRG-2_C156248.pdf). To my knowledge, it fulfills the requirements from NXP:Measurements at XTALO with an oscilloscope seem, to a rookie, ok:Here's my schematic:And my layout:I did make the rookie mistake of copying the capacitors for the XTAL from a schematic. My design has 12pF, but my calculations show that 6-8pF may be better (Cl = 8pf, Cstray = ~4-5pF).Any obvious mistakes or things I can check?I've also checked that the power supplies are all and stable. Measurements with the oscilloscope at the capacitors closest to the pins show stable voltages and within the ranges specified in the Hardware Design Guideline:I also measured RTC_XTALO:I know that the chip has to start up in a certain way and there's requirements for Por_B, but the start up appears to conform to the requirements in the Hardware Design Guideline:I've also posted some additional information here:https://forum.pjrc.com/index.php?threads/custom-pcb-board-with-mimxrt1062dvj6b.74992/My device can be powered by USB or a 12V supply. The issues are independent of the power supply and whether the USB is plugged in or not.The board was manufactured by JLCPCB with FR-4 TG155, ENIG and JLC04161H-3313.I'd appreciate any and all help.Regards,Sam

author: cortex_m0
author_rank: Regular Contributor
timestamp: May 17, 2024, 02:20:03 am
content: The amplitude of the 24MHz clock is low. 128mV p-p is actually very low. I like to see at least 0.5V on those pins.Note, NXP does not list a minimum, and I am not deeply familiar with these chips. This is based on my intuition.For a quick test, desolder your crystal. Connect a signal generator to XTALI. Follow the amplitudes listed in Table 21 "XTALI and RTC_XTALI (clock inputs) DC parameters".Additionally, I would say that an IMXRT10xx is quite a large project for someone's first PCB.

author: aliarifat794
author_rank: Regular Contributor
timestamp: May 18, 2024, 06:54:58 am
content: I think the 12pF capacitor value should be decreased.

author: SamS
author_rank: Newbie
timestamp: December 05, 2024, 11:50:12 pm
content: Hello All,I appreciate the input and I recognise I jumped straight in the deep end.For anyone who should experience something similar, my clocks, power steps were all correct.I made the rookie mistake of the wrong footprint for on my USB data filter hardware, DP changed to DN.At startup the device must check USB (potentially for booting etc.) and it caused the device to lock up. Correct USB lines and the board works perfectly.