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Electronics => PCB/EDA/CAD => KiCad => Topic started by: bd139 on January 18, 2018, 12:35:48 pm

Title: PWR_FLAG vs input pin on 4027 JK FF
Post by: bd139 on January 18, 2018, 12:35:48 pm
I've got a 4027 which I've tied both Sd to ground on. gnd is marked with PWR_FLAG. This is an input pin in theory but the ERC is showing error as follows:

(https://i.imgur.com/ElQ8gyj.png)

Schematic:

(https://i.imgur.com/ysaM9Pk.png)

In theory the Sd pin should be both grounded and both inputs.

Any ideas how to proceed on this one to pass the ERC? Is this a bug in the symbol i.e. the pin should be an input?
Title: Re: PWR_FLAG vs input pin on 4027 JK FF
Post by: fable on January 18, 2018, 01:34:03 pm
Edit library... Change the state of that pin
Title: Re: PWR_FLAG vs input pin on 4027 JK FF
Post by: bd139 on January 18, 2018, 01:54:05 pm
That did the trick. Bug in kicad library then!

Thank you :)
Title: Re: PWR_FLAG vs input pin on 4027 JK FF
Post by: hermit on January 18, 2018, 04:35:03 pm
Quote from: bd139 on January 18, 2018, 01:54:05 pm
That did the trick. Bug in kicad library then!

Thank you :)
The fact you ground them for your application doesn't make this a bug.  The data sheet I'm looking at says "1SD, 2SD
 9, 7 asynchronous set-direct input (active HIGH)".  Why would the library list it as a power pin?
Title: Re: PWR_FLAG vs input pin on 4027 JK FF
Post by: bd139 on January 18, 2018, 06:00:50 pm
https://www.intersil.com/content/dam/Intersil/documents/cd40/cd4027bms.pdf (https://www.intersil.com/content/dam/Intersil/documents/cd40/cd4027bms.pdf)

Page 6. IC schematic. Definitely inputs. Were marked as outputs in library.
Title: Re: PWR_FLAG vs input pin on 4027 JK FF
Post by: donotdespisethesnake on January 20, 2018, 08:33:21 am
I found several issues like this when I reworked the CMOS library, it should be fixed in the latest version.
Title: Re: PWR_FLAG vs input pin on 4027 JK FF
Post by: bd139 on January 20, 2018, 01:23:15 pm
Cool. Thank you  :-+