GPIO_AD_B1_12 not working (i.MXRT 1062)

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GPIO_AD_B1_12 not working (i.MXRT 1062)

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bennxp
Contributor III

I have a custom board with an MIMXRT1062 on it and I'm seeing strange behavior on only one pin. That pin, GPIO_AD_B1_12 is acting like it isn't connected to the PCB:

  • If I configure the pin as an output, setting it high or low has no affect on the output of the pin.
  • If I configure the pin as an input with a pullup resistor it reads high no matter what voltage is on the pin
  • If I configure the pin as an input with a pulldown resistor it reads low no matter what voltage is on the pin

All other pins in the GPIO_AD_B1 bank work perfectly through all those tests. I have 5 boards. One 3 of them, all the pins works fine. On 2 of them, I get this bad behavior just on this one pin. While this could be an assembly issue, the boards were electrically tested and the iMXRT processor was x-rayed after assembly. Pressing down on the chip does not temporarily fix the problem. Given that I'm seeing identical problem on the same 1 pin across 2 boards. a bad solder joint seems somewhat unlikely, so I'm trying to rule out other possibilities.

Is there anything special about the GPIO_AD_B1_12 pin?

Is there a Fuse setting that would redirect the H12 pad away from normal GPIO functionality?

Is there some pin read at boot that might configure this pad to be repurposed?

Any ideas on what could cause this behavior other than a bad solder connection on the pad to the PCB?

 

For reference, here is how I configure the pin for different settings:

IOMUXC_SW_MUX_CTL_PAD_GPIO_AD_B1_12 = 0x15; // Set pad as GPIO
IOMUXC_SW_PAD_CTL_PAD_GPIO_AD_B1_12 |= 0x80 // Set bit 15 for 100k pull up
IOMUXC_SW_PAD_CTL_PAD_GPIO_AD_B1_12 &= ~0xC0 // Clear bits 14 and 15 for 100k pull down
GPIO1_GDIR = 0x1000; //Set pin as output
GPIO1_GDIR = 0x0000; //Set pin as input
GPIO1_DR_SET = 0x1000; //Set pin high
GPIO1_DR_CLEAR = 0x1000; //Set pin low

 

 Thanks!

 

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bennxp
Contributor III

I was able to confirm that the issue was a bad solder joint. Thanks for the help.

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jeremyzhou
NXP Employee
NXP Employee

Hi,
Thank you for your interest in NXP Semiconductor products and for the opportunity to serve you.
It seems a bit weird and I guess the issue is related to hardware.
In addition, I'd like to suggest you use the below code line to configure the GPIO_AD_B1_12 pin as GPIO1_IO28.

IOMUXC_SW_MUX_CTL_PAD_GPIO_AD_B1_12 = 0x5; // Set pad as GPIO


Have a great day,
TIC

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bennxp
Contributor III

Thanks for the quick reply.  I changed from 0x15 to 

IOMUXC_SW_MUX_CTL_PAD_GPIO_AD_B1_12 = 0x5; // Set pad as GPIO

and it made no difference.

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jeremyzhou
NXP Employee
NXP Employee

Hi,
Thanks for your reply.
According to your statement, I think the GPIO_AD_B1_12 pin is floating, in other words, the pad is not assembled well.
I'd like to suggest you use the GPIO_AD_B1_12 as ADC2_IN1to to check whether ADC2 detects the analog signal that connects to the pad.

jeremyzhou_0-1638497279415.png


Have a great day,
TIC

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bennxp
Contributor III

Thanks, that's a really good idea. The boards are currently out for inspection of their solder connections. Assuming they doesn't find anything, I'll do this test when I get the boards back. 

Thanks,

 

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bennxp
Contributor III

I was able to confirm that the issue was a bad solder joint. Thanks for the help.

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