When the peripheral device is connected, the 5V voltage of 40PIN is pulled down and the voltage of SPI SCK is pulled down too

[jdsb]

I want to use 40pin header.
when any peripheral is connected, I find that the 5V voltage is pulled down and the peripheral can’t start running. The voltage changes from 5V to 2.2V. my device does not have any high power devices, only two stm32 chips or 1 nrf51822 chip.

Therefore, I don’t use jetson-NX for power supply.Instead, I connect SPI-SCK,SPI-MOSI,GND directly to my peripheral. But I also found that the spi-sck and spi-mosi voltages are also pulled down.

I have already configured the SPI using the jetson-IO tool. When the spi pins of jetson-NX are not connected to any device, they are 0V-3.3V. Once another device is connected, the voltage of spi-sck becomes 0-1.5V or 0-2V

some picture and movie
no connect

connect

Uploading: 2df1e5a93a6880186bce03f0108aa93c.mp4…

[ShaneCCC]

@Trumany
May I have your comment for this topic.

Thanks

[Trumany]

Hi, please refer to below 40-pin docs in DLC first. There are some requests on the external device.

https://developer.nvidia.com/jetson-nano-developer-kit-40-pin-expansion-header-gpio-usage-considerations-applications-note

https://developer.nvidia.com/embedded/dlc/Jetson-Nano-40-Pin-Expansion-Header-1.1

[jdsb]

Thank you very much, according to your suggestion, I have successfully solved the problem of SPI voltage, but there is still a problem left above. I tested all the 5V and 3.3V voltages, only 3.3V is normally powered, but the 5V connected device immediately dropped to 2.2V

[jdsb]

How much current can be drawn from pin2/4 of 40 pin header

Also could you send a picture of the rework so as to check how 220ohm was soldered? As it is very strange. Q23 is a P-FET so if its gate is at 0V and drain is 5.11V, then source should be also at 5.11V and not 1.99V.

I found a similar problem, and according to the description here.

no connect.
Q23 drain(to 5V_SYS) is 5V, source (to 5V_GPIO) is 5V, gate is 0V.

is connected
Q23 drain(to 5V_SYS) is 5V, source (to 5V_GPIO) is 2V, gate is 0V.

[jdsb]

emmmm.
I find anthoer jetson-NX, it’s 5V output is ok.

[Trumany]

If so, seems the previous module has issue on this. You can run RMA for it if necessary.