IMX8MN USB OTG not recognized (when doing ddr test)

AccuJie — Tue, 16 Nov 2021 21:53:48 GMT

We have three customized IMX8MN boards. Now, we are trying to do the ddr training & stress test.

However, two of our boards are not recognized by the PC at all. Another one just got a warning of USB device not recognized. We already changed the boot mode to serial download mode.

Of cause we got the error inside ddr training and stress test tools:

ERROR: Can't open USB device!!!
Please check if the correct target is selected and set to the serial download mode

We are using the PMIC of PCA9450 with a 2Gb DDR4. Here is the power rail supply from the pmic I measured(when in serial download mode before firmware download):

VSYS_5V	5V
PCA9450B_BUCK1(VDD_SOC&VDD_DRAM)	0.85V
PCA9450B_BUCK2(VDD_ARM)	0.85V
PCA9450B_BUCK4(VDD_3V3/NVCC_3V3)	3.3V
PCA9450B_BUCK5(VDD_1v8/NVCC_1V8)	1.8V
PCA9450B_BUCK6(NVCC_DRAM)	1.1V
PCA9450B_LDO1(NVCC_SNVS_1V8)	1.78V
PCA9450B_LDO2(VDD_SNVS_0V8 )	0.8V
PCA9450B_LDO3(1V8_VDDA)	1.8V

Base on my understanding, the firmware download in ddr test tools(download into on-chip internal RAM) only needs the basic voltage(default config).

Where should I have a check in the next step?

Thanks.

Re: IMX8MN USB OTG not recognized (when doing ddr test)

igorpadykov — Tue, 16 Nov 2021 23:36:24 GMT

Hi Jie

for that issue one can check sect.Table 8. USB recommendations, clock stability

using sect.Table 10. Oscillator/Crystal recommendations i.MX 8M Nano Hardware Developer’s Guide

Best regards
igor

Re: IMX8MN USB OTG not recognized (when doing ddr test)

AccuJie — Fri, 19 Nov 2021 18:37:46 GMT

Thanks for your suggestion. We found out that the problem is from our oscillator.

i.MX ProcessorsのトピックIMX8MN USB OTG not recognized (when doing ddr test)

IMX8MN USB OTG not recognized (when doing ddr test)

Re: IMX8MN USB OTG not recognized (when doing ddr test)

Re: IMX8MN USB OTG not recognized (when doing ddr test)