PiUPShield - Looking for Input

[TexasStingray]

Wanted to get a group discussion started here about having a Pi HAT/Shield here that would be a battery backup for you pi that would trigger a GPIO that would let the pi know that it is running on battery power to take action. I think that it would require 2 GPIO's so that the shield knows when the Pi has shut down so that it removed the batteries power from the pi so that when the mains power is back it triggers a start of the Pi.

[Bwinter]

What type of "action" would it take if it recognized it's on battery?


If the Pi is "shut down," how would a GPIO trigger it to start back up?

[TexasStingray]

Action would depend on the script, but in most cases if there is no mains power then there is not enough power to run the light show show it should shut down. The Pi by default when power is applied to it would power on. So when the mains power is on then the pi would start up as usual. Then when the mains power is cut off for some reason the shield would kick in keeping the pi up and triggering the GPIO which the script would recognize and take action. Then when the 2nd GPIO goes LOW because the pi is shutdown the shield would have to kill its power going to the pi, so that when the mains power does come back on it would trigger a normal startup.

[CaptainMurdoch]

This sounds like a good idea to me.  There are some commercially available solutions, but they seem to cost as much as or more than the Pi.

[k6ccc]

I'm watching this thread...  Very interested to see where this goes...

[TexasStingray]

Looking for the developers out there that have developed HATS for the Pi, that have made them available to others! What GPIO pins are available for use?

[CaptainMurdoch]

Most of the pins used by the various Hats are documented on the Channel Outputs popup help page in FPP.  The RGBMatrix output needs updating as it now can use almost all the pins to drive the 3 chains of LED panels.

If you are looking for pins to avoid, avoid the PCM and i2c pins unless you need i2c.  The newer version of the ws281x library has the option of using those to drive pixels and I may see if I can drive 4 strings of pixels off the Pi at one time using those and the two PWM outputs we currently use.

[TexasStingray]

Maybe i should allow the user to set jumpers for the pins to use?

[Bwinter]

Most of the pins used by the various Hats are documented on the Channel Outputs popup help page in FPP.  The RGBMatrix output needs updating as it now can use almost all the pins to drive the 3 chains of LED panels.

If you are looking for pins to avoid, avoid the PCM and i2c pins unless you need i2c.  The newer version of the ws281x library has the option of using those to drive pixels and I may see if I can drive 4 strings of pixels off the Pi at one time using those and the two PWM outputs we currently use.

Wait....you're saying the Pi could potentially drive 4 WS281x strings, instead of just the two that we're accustomed to??

[CaptainMurdoch]

Wait....you're saying the Pi could potentially drive 4 WS281x strings, instead of just the two that we're accustomed to??

I am not sure yet but the possibility exists.  I believe the updates version of the library supports outputs over PWM, PCM/SPI, and i2c but I am not sure if it can do all at the same time.  Even if it can't, do all at the same time, I want to explore using the other outputs.  The advantage of using those will mean you could still use the onboard PWM audio while driving pixels at the same time.

[Bwinter]

How soon would this be implemented?  In enough time to develop new boards that could take advantage of this for the upcoming season?

[CaptainMurdoch]

How soon would this be implemented?  In enough time to develop new boards that could take advantage of this for the upcoming season?

I plan on upgrading the library used in the master branch sometime soon and will then regression test the existing PWM method and also test the new output methods to get them working and see if I can drive 3-4 at the same time.

[TexasStingray]

Working on this and having a great time learning. Using a breadboard I've been able to run my Pi Zero W with the main power and the power pack hookup up at the same time and when i cut the main power the pi keeps on running off the power pack. Using FPP GPIO I've been able to trigger a shutdown script. Next is to edit the script to check to wait some period of time and see if the main power is still off or take action.
have been able to run

[Bwinter]

Most of the pins used by the various Hats are documented on the Channel Outputs popup help page in FPP.  The RGBMatrix output needs updating as it now can use almost all the pins to drive the 3 chains of LED panels.

If you are looking for pins to avoid, avoid the PCM and i2c pins unless you need i2c.  The newer version of the ws281x library has the option of using those to drive pixels and I may see if I can drive 4 strings of pixels off the Pi at one time using those and the two PWM outputs we currently use.

Was this ever implemented?  Can a RPi now drive 4 separate ws281x outputs?

[Bwinter]

How soon would this be implemented?  In enough time to develop new boards that could take advantage of this for the upcoming season?

I plan on upgrading the library used in the master branch sometime soon and will then regression test the existing PWM method and also test the new output methods to get them working and see if I can drive 3-4 at the same time.

Still curious on where this project ended up (the ability to drive 3-4 strands off a Pi).