Resistive Pull Up/Down GPIO Not Correct Voltages

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RyWi_4724536
Level 3
Level 3
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I found that when I set a GPIO drive mode to resistive pull up/down the voltages are 2.5V high, and 1V low. 

In strong drive mode setting the pin high is correct at 3.3V and low correct at 0V.

With drive mode set to resistive pull down I see 3.3V high, 1V low

With drive mode set to resistive pull up I see 2.5V high, 0V low

Any idea why this is happening? I would like to use resistive pull up/down drive mode and have the gpio output 3.3V and 0V when I set it high or low

I am using CY8C6347LQI-BLD52 pin P7.2

 

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Len_CONSULTRON
Level 9
Level 9
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RyWi,

Hi.  Do you have any external components attached to P7.2?   Resistors ... maybe?

Len
"Engineering is an Art. The Art of Compromise."

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Len_CONSULTRON
Level 9
Level 9
Beta tester 500 solutions authored 1000 replies posted

RyWi,

Hi.  Do you have any external components attached to P7.2?   Resistors ... maybe?

Len
"Engineering is an Art. The Art of Compromise."
RyWi_4724536
Level 3
Level 3
10 replies posted 10 questions asked 10 sign-ins

Good catch! I didn't realize I had a pull up resistor populated there

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RyWi,

Good deal!   If you have a bias resistor (pull-up) already on the pin, you don't need to have resistive elements in the GPIO pin.

You can probably use Open Drain Low mode.  Note: depending on the value of your external pull-up and the total capacitance on the circuit connected to P7.2, you will get fast fall times but the rise time will be limited by the pull-up resistance times the total cap.

Len
"Engineering is an Art. The Art of Compromise."