GPIO2_0 is low

Designing hardware and software for systems that use the VS1010 MP3 Audio DSP Microcontroller.
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Arek
Senior User
Posts: 53
Joined: Thu 2016-09-01 10:58

GPIO2_0 is low

Post by Arek » Fri 2018-08-17 13:48

Hi,
my application use GPIO2_0, GPIO2_1 and GPIO2_2 as inputs pins. They are connected to optocouplers output transistor with 4k7 pull-up to IOVDD.
Program is running and all three inputs works well. After checking with oscilloscope the GPIO2_0 shows something else to the others inputs as well as awaiting.
Instead of near 2V8 (pull-up to IOVDD, output transistor of opto is off) I get near 0V with short peaks (19us) to 2,8V. The peaks are coming when my program checks the inputs (GpioReadPin(0x20)).
I haven’t found anything in the datasheet where this phenomenon comes from.
Perhaps making output pin with 4k7 pull up is nothing danger but, I think, also not necessary.

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