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PSoC 4 MCU

AdRa_4011776
New Contributor

We are using the CYBLE-214015-01 microcontroller, in one of its pins we configure it as "High Impediance Analog" or "Open Drain" and connect it to an LED, the power of the microcontroller is 2.5V, and for the LED it is 5V Then according to the configuration that we have adjusted when a 1 or 0 is sent to the pin output, it should be floating, that is, the LED should be completely off or on depending on the configured mode, but it happens that when we want to turn off the LED (with any of the settings), it remains illuminated. Could someone explain to me why this happens?

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3 Replies
VenkataD_41
Moderator
Moderator

Hi,

There will be two protection diodes that are present on every GPIO  pulled to VDDIO and ground irrespective of the drivemode of the pin. Please refer the page number from the device architecture TRM obtained from link below:

https://www.cypress.com/file/137266/download

Since the voltage level of PSoC is different from LED voltage, there is always a forward drop between LED power supply and the PSoC. This is the reason you are facing this issue. You can make both PSoC voltage as well as LED voltage as same then you wont see the LED glowing.

Thanks

Ganesh

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AdRa_4011776
New Contributor

Thank you very much for the information, we already knew that, but we don't believe that the problem has to do with the diodes. Regardless of that, the output should be floating, there should be no voltage.

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VenkataD_41
Moderator
Moderator

Hi,

If possible please connect and see both PSoC voltage and external voltage that drives LED to same voltage level. If this makes the LED glow then there is a problem with the module. Please confirm this.

Thanks

Ganesh

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