GPIO pins only provide 1,8V

#1

Hi everyone,
I just recently bought the Rock Pi X (revision 1.4). With libmraa I am trying to control the GPIO pins. Setting them to high and resetting them to low works as it is supposed to. Unfortunately the voltage on any pin is only 1.8 Volts when set to high.

A friend with way more understanding of these things studied the schematics and the data sheet of the UM3204 level shifter and following the logic it seems as if there was a possibility that this part was connected the wrong way (UM3204 B channel to CPU, A channel to GPIO connector) and therefore not compliant with the UM3204 rule VCCA <= VCCB.
The available schematics for V1.3 show correct connection but V1.4 board layout and UM3204 placement point to a modification there… or the footprint drawing was mirrored.

Both 1v8 and 3v3 voltages are measurable and ok (only 3v3 measurable directly at um3204 due to ball grid layout).

Can anyone confirm this?

Logic Level Converter
#2

Tested GPIO335, Rev1.4:
Set to Low: 0.03v
Set to High: 1.83v

#3

Nice catch. Indeed the UM3204 footprint was mirrored…

#4

what is the solution? I was planning to use the SPI port which appears to use the same UM3204.

#5

I was about to ask the same thing.
Getting in touch with the dealer for a replacement probably will only result in getting another Rev1.4 with the same problem.

#6

It is very disappointing to hear this. Mine is still in shipment, at least I haven’t started doing any development on it yet. I doubt it is worth returning it, but I don’t think I have any use for it now.

#7

That’s a joke, how can something like that happen?
Was there no quality control here?
Was the product not extensively tested?
Something like this would not go undetected if it had been tested.
I spent € 125 for it, how do you think to solve the problem?

1 Like
#8

Is there a board file that shows the routing of the traces? I couldn’t find it on the wiki page. but I wanted to know if we can cut and swap traces to bypass the UM3204 chip. the schematic file appears to be correct.

#9

Guess it is time to build some logic level translators. You can use the 3.3V on the GPIO and a simple 1.8V regulator with the logic level translators to interface them. Will be trying this soon.

#10

@jack, does this issue exist in all v1.4 boards? Or has it been fixed in later v1.4 boards now that it has been discovered?

#11

It is a problem that the pins output 1.8v. However, if the input voltage of the pins is 1.8V, it will be a big problem.

#12

Is this issue fixed on new version of board? I also found same issue on my V1.4 Rock Pi X board. But I need 3.3V GPIO input/output on Rock PI X side. Any solutions?

1 Like
#13

@jack Is there any update for the solution for this problem?

#14

V1.41 revision fixed this issue. Tested and confirmed by the Intel Team in Shanghai.

#15

jack,
When will the V1.41 RockPiX boards be available? All of mine are V1.4 version boards.

HAL

#16

wait @jack , does this mean the boards that are being currently sold still have this problem and just a future batch of new boards will have it solved?

I bought mine one week ago from here:https://shop.allnetchina.cn/collections/frontpage/products/rock-pi-x

#17

One week ago, it should be the new version. Check the silkscreen on the board, v1.41 is the right version.

#18

Sorry, I mixed it up the terms, it arrived one week ago, but I bought 20/07 and the version on the board is 1.4. So it probably still have the problem

#19

@jack,
Thanks for the update.

Am I correct that the GPIO I2S Bus audio interface pins that are available are not going through any UM3204 level converters from the SoC? I do not see it in the schematic for V1.3 which is the same as the V1.4 version. If so, I can design my own 1.8V to 3.3V logic level interface for an external DAC.

Please let me know.

Best regards,

#20

@jack the board I bought on the 20/07 has 1.4 on the silkscreen, so this version still has the pins problem?(I am asking because for the foreseeable days I am unable to test it)