Digital Output pin connected to Logic Low '0'

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Anonymous
Not applicable

Hello,

When I directly connect Logic Low '0' to Digital Output Pin, it seems that the output pin should be always Low but it is always high voltage when I checked the output pin with Digital Multimeter.

Why is its output always high?

Best regards,

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Add my project. if you find any problem, please let me know anything.

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Bob_Marlowe
Level 10
Level 10
First like given 50 questions asked 10 questions asked

I assume that the fitter optimizes-out the unused (always zero) pin. Since no clock can toggle the input it will stay as during initialization.

Way out: Remove the hadware connection and set the initial drive mode to "strong" and "low".

Bob

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GyanC_36
Employee
Employee
250 replies posted 100 replies posted 50 replies posted

Hello,

    Yes , if you have connected a Logic '0' to an output pin configured as 'Hardware Connection' should give a logic Level '0'.

Please check your pin configuration as below -

     Pin_Config.PNG

Refer the attached project.

-Gyan

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Anonymous
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Hello Gyan-san,

I checked my project and the pin configuration is perfectly same as your project except Pin position. I use P0_0 of CY8C4045AZI-S413.

Also I checked this on CY8CIT-145-40XX, PSoC4000S Prototyping it.

Thanks and regards,

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RyanZhao
Moderator
Moderator
Moderator
250 sign-ins First question asked 750 replies posted

Okegawa-san,

Could you double-check if there is any external pull-ups on the pin?

Which pin in which kit/chip/board were you using to test the case?

I tried with KIT-042, used P0_0.

Used logic '0' to connect the pin internally. The result of digital multimeter is 0V.

Used logic '1' to connect the pin internally. The result of digital multimeter is 5V.

Thanks,

Ryan

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Anonymous
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Hello Ryan-san,

I checked schematic again but there is no pull-up register. That pin is connected to LED through 820 ohm resister. I use CY8CIT-145-40XX and although I divided the sub board including slider touch sensor and checked P0_0 pin voltage, the P0_0 is always high, about 4.74v.

Thanks and regards,

...

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Anonymous
Not applicable

There are no macro cells in this device to allow this hardware connection. Creator should not have allowed. It throws error when I connect Logic 1. Creator can possibly optimize it by writing initialization code before calling main function. Initialization code for the pin in the function cyfitter_cfg() seems to be taking what is appearing in the pin customizer window and not based on what logic level, it is connected to. I have asked the software team to have a look into it.

Thanks for bringing it to our notice. As a workaround, please uncheck hardware connection in the pin customizer window and control the pin logic level in firmware.

-Rajiv 

odissey1
Level 9
Level 9
First comment on KBA 1000 replies posted 750 replies posted

It is possible that pin is fried. Set the initial state on startups to 0. If after programming it shows +5V, the pin's high-side FET is fried.

/odissey1