Trouble with internal pull ups on i.mx6

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Trouble with internal pull ups on i.mx6

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adamgarrison
Contributor III

I’m seeing odd behavior with the internal pull-ups on the i.mx6.

When I configure a GPIO as in input and enable the pull-up, it yanks the input very strongly high.  If I tie a 100k pull-down externally, it doesn’t change the voltage at the input.  If I tie the input directly to ground, it sources ~95mA.  I’m positive it’s not configured as an output.  If I disable the pull-up through a register write, it no-longer does this behavior.

Any suggestions on what could be causing this?

FYI,

The particular register I’m using to control the pull-up is IOMUXC_SW_PAD_CTL_PAD_EIM_ADDR21.

I have it configured as a GPIO2_17 through the MUX_MODE bits in IOMUXC_SW_MUX_CTL_PAD_EIM_ADDR21

I have bit 17 in GPIOx_GDIR cleared (where x = 2).

Thank you,

Adam

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adamgarrison
Contributor III

this was a circuitry issue.  Buffers exterior to the device were responsible.