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PiTFT 3.5" Plus: How to initialize w/o the onboard EEPROM
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PiTFT 3.5" Plus: How to initialize w/o the onboard EEPROM

by Eierkuchen on Fri Mar 27, 2020 10:47 am

Hi,
I just purchased this little display for a bedside clock project with internet radio and music player.
I already have an audio hat attached on my Pi. But now I become aware that hats are not stackable, because the hat spec foresees only one EEPROM on the I2C bus on address 0. This is the reason why pins 27 and 28 (EEDATA and EECLK) are not accessible on one hat to other hats.

Since I want to operate the display apart from the Pi anyway connecting it with a cable attached on the 26 pin GPIO header, I won't connect pins 27 and 28 at all.

I just wonder then whether it is sufficient to run the installer script to set up the DT overlay or what else has to be configured manually in absence of the EEPROM which normally initializes the hat?

The DT overlay is probably stored in the EEPROM. So where can I get the DT overlay and which one? Does it already exist in the most current Raspian?

Would appreciate any helpful hint.

Eierkuchen
 
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Joined: Thu Mar 26, 2020 10:22 am

Re: PiTFT 3.5" Plus: How to initialize w/o the onboard EEPRO

by Eierkuchen on Fri Mar 27, 2020 11:02 am

Meanwhile I looked into the adafruit-pitft.sh script and understood that it updates the config.txt for the display pointing to the DTO which exists already i the overlays folder. It als takes care of some fb settings, rotation, SDL tweaks, etc.
So it seems the script sets up everthing to make the display work.

I still wonder then what the purpose of the EEPROM is and what might be left to manual configuration if the Pi does not detect the (not connected) EEPROM.

Perhaps somebody can shed some light on this situation.

Eierkuchen
 
Posts: 2
Joined: Thu Mar 26, 2020 10:22 am

Re: PiTFT 3.5" Plus: How to initialize w/o the onboard EEPRO

by har1eyk on Wed Nov 11, 2020 4:48 pm

Hi, the response to this question may help you.

viewtopic.php?f=50&t=171697&p=838332&hilit=eeclk#p838332

har1eyk
 
Posts: 9
Joined: Sat Mar 24, 2018 3:54 pm

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