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Pi 3 + pHAT DAC + 7 Inch Touchscreen in Case
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Please be positive and constructive with your questions and comments.

Pi 3 + pHAT DAC + 7 Inch Touchscreen in Case

by JonnyAlpha on Fri Dec 09, 2016 8:03 am

Hi;

I need a little help here please. I am building an in car entertainment system for which I have bought a Raspberry Pi 3 and an official 7 Inch Touch Screen with case.
The sound from the Pi 3 3.5mm Audio Out was rubbish so after doing some investigation went ahead and bought a pHAT DAC (The Zero version). I bought the Zero version because whilst looking I read that it would fit inside the 7 Inch Touch Screen.

My pHAT arrived today and on looking at the back of the 7 Inch Touchscreen I remembered that 3 of the GPIO pins are in use as it is wired to power the Pi from the Touchscreen. This means that with the pHAT in place on its header I will not be able to plug these power pins in as (a) there will be no header protruding from the pHAT and (b) the pins will stick out too far to fit the back of the Touchscreen case on.

Anyone have any solutions that I can try?

JonnyAlpha
 
Posts: 5
Joined: Sat Nov 05, 2016 2:57 pm

Re: Pi 3 + pHAT DAC + 7 Inch Touchscreen in Case

by Hakugin on Fri Dec 09, 2016 1:35 pm

JonnyAlpha wrote:Hi;

I need a little help here please. I am building an in car entertainment system for which I have bought a Raspberry Pi 3 and an official 7 Inch Touch Screen with case.
The sound from the Pi 3 3.5mm Audio Out was rubbish so after doing some investigation went ahead and bought a pHAT DAC (The Zero version). I bought the Zero version because whilst looking I read that it would fit inside the 7 Inch Touch Screen.

My pHAT arrived today and on looking at the back of the 7 Inch Touchscreen I remembered that 3 of the GPIO pins are in use as it is wired to power the Pi from the Touchscreen. This means that with the pHAT in place on its header I will not be able to plug these power pins in as (a) there will be no header protruding from the pHAT and (b) the pins will stick out too far to fit the back of the Touchscreen case on.

Anyone have any solutions that I can try?


If your power supply is connected directly to the official pi touchscreen there is a USB port on the screen you can use to power the Pi. Essentially daisy chaining power to the Raspberry Pi.

Now, I have a question for you. Will this be replacing your factory (otherwise pre-existing) stereo/infotainment unit in the vehicle? If so please keep in mind that the RPi can take a couple minutes to fully boot up, which is much longer than other available options.

Hakugin
 
Posts: 119
Joined: Tue Oct 13, 2015 1:18 pm

Re: Pi 3 + pHAT DAC + 7 Inch Touchscreen in Case

by JonnyAlpha on Fri Dec 09, 2016 3:10 pm

Thanks for the reply.
Managed to resolve the power and GPIO issue by connecting the pHAT DAC using some dupont connectors.
Power is supplied via a Mausberry 3A PSU which is designed to boot the Pi when the Ignition is turned on and shut the Pi down when its turned off.

Here is my blog (work in progress).

https://picodeandchips.wordpress.com/20 ... d-content/

JonnyAlpha
 
Posts: 5
Joined: Sat Nov 05, 2016 2:57 pm

Re: Pi 3 + pHAT DAC + 7 Inch Touchscreen in Case

by Hakugin on Fri Dec 09, 2016 6:03 pm

I read the blog post that you linked. I have to admit, while I had tried something similar earlier this year, I shelved my project.

I found there were a lot of "variables", as they say, that need addressed.
- Boot times
- General response time
- Type of storage
- Reliability

Those are just the main things I came across in my endeavor. Perhaps we can collaborate and combine our findings.

Hakugin
 
Posts: 119
Joined: Tue Oct 13, 2015 1:18 pm

Please be positive and constructive with your questions and comments.