AnsweredAssumed Answered

Open drain Input to PTA17

Question asked by Tomoki Okuno on Sep 29, 2013
Latest reply on Oct 9, 2013 by jiri-b36968


Hi all,

 

We use PTA17(GPIO7) as open-drain input,and mount the external pull-up resistor of 10k Ohm.

The power supply is 3.3V same as VDD33 on Vybrid.

 

But, Hi level input to PTA17 will not be 3.3V.

We can see it about 1.0V.

 

We guess that there is a current leak path to ground,about 1k Ohm.

 

Off course, We checked the register settings,

IOMUXC_PTA17=0x2051

MUX_MODE=000, PUE=0, OBE=0, IBE=1.

 

We tried changing the register settings.

Only when we set to MUX_MODE=111(I2C), We can see Hi level 3.3V.

 

This behavior could also be seen in the PTB0 and PTC31 that we use as open-drain input as well.

 

We want you to find any errors in the circuit or register settings.

 

In our circuit, VDD12_AFE, VDDA33_AFE, VDDA33_ADC tie directly to ground,

as it is indicated in the reference manual.

 

Best Regards,

Tomoki

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