recklessfb
Posts: 37
Joined: Wed Jul 06, 2016 12:26 am

Sensehat ground pins?

Sat Feb 04, 2017 2:40 am

Hello,
I currently have my sensehat connected to my pi3 using an extended header but since I have some spare dupont cable lying around, I want to use them instead. I understand the sensehat uses 6 data GPIOs, 1 3V and 1 5V pin. My question is how many ground pins does it need? 1 or 2?
I did look at http://pinout.xyz/pinout/sense_hat# but I am still confused. Yes, I could connect all the pins with the dupont cable but I only want to connect the pins in use and leave the rest for a PIR sensor.

Thanks for your help.

User avatar
rpdom
Posts: 15023
Joined: Sun May 06, 2012 5:17 am
Location: Chelmsford, Essex, UK

Re: Sensehat ground pins?

Sat Feb 04, 2017 7:50 am

Looking at the Schematic for the Sense Hat (linked to by that page), you only need to connect one Ground pin and you can use any of them for that.

I'd say for normal use you could connect just pins 1, 2, 3, 5, 6, 16, 18, 22, 24, 27 and 28.

If you need to reprogram the Atmel chip for any reason you'll also need to connect pins 19, 21 and 23, but you don't need to do that unless you need to update the code in the Hat itself.

Just for clarification, when it refers to "6 gpios", it doesn't include the power connections (1, 2 & 6) or the Hat ID connections (27 & 28).

User avatar
ahaughs
Posts: 6
Joined: Fri Apr 29, 2016 2:20 am

Re: Sensehat ground pins?

Thu Feb 16, 2017 2:25 am

FANTASTIC! Thank you-- this is exactly the information I was looking for! I'd used Pinout.xyz but, like you said, pins 27 & 28 aren't highlighted and that was causing me issues as I couldn't figure out what was missing on my own. Got everything working perfectly now!
Amanda Haughs
@mshaughs

MikalL
Posts: 2
Joined: Thu Jun 01, 2017 7:42 pm

Re: Sensehat ground pins?

Thu Jun 01, 2017 7:48 pm

Different hat, same problem.
Thanks for clearing up the ground pins, but do ALL hats need pin 27 and 28 too?

I'm trying to wire the PiTFT, but I have a hard time figuring out which pins to wire.
https://pinout.xyz/pinout/pitft_plus_35#

Would this be the complete list?
1, 2, 6 (or another GND), (12), 18, 19, 21, 22, 23, 24, 26 and then 27 and 28?

Mikal

User avatar
rpdom
Posts: 15023
Joined: Sun May 06, 2012 5:17 am
Location: Chelmsford, Essex, UK

Re: Sensehat ground pins?

Fri Jun 02, 2017 4:05 am

All HATS require pins 27 and 28. That is in the official HAT specifications. Not all add-on boards are called HATs.

The PiTFT specs I found seem to have the ID chip that uses pin 27 and 28, but aren't referred to as HATs. Perhaps they don't meet the specifications in some other way.

MikalL
Posts: 2
Joined: Thu Jun 01, 2017 7:42 pm

Re: Sensehat ground pins?

Fri Jun 02, 2017 5:47 am

Thanks for the quick reply!
Is there any sure-fire way for figuring these kinds of things out?
Because Adafruit is not really clear on the pins.
Or maybe (probably) I'm just looking in the wrong places...

User avatar
bensimmo
Posts: 4162
Joined: Sun Dec 28, 2014 3:02 pm
Location: East Yorkshire

Re: Sensehat ground pins?

Fri Jun 02, 2017 6:48 am

Sure fire way, ask the manufacturer or shop you get it from.

Return to “HATs and other add-ons”