Hi everyone. Hey I’m working on a project and I need some help on hardware suggestions. And a disclosure I’m very inexperienced with this. So, I have a Pi 4b and I have a Hyperpixil 2 ¼”X3 ¾” touch screen display attached to it using the 40 pin GPIO header and what appears to be a 8mm stacking header with 14mm standoffs that came with the display.
So, I would like to add a fan and a battery to this project. The problem with a fan is that there isn’t enough room between the Pi and the display to fit one in and also all the fans I’ve seen are plugged into the 40 pin GPIO header and that isn’t available because of the display. Also it would be nice if the fan was controlled by a thermostat. What is the best solution here? Maybe a low profile fan and a taller stacking header and longer standoffs? I’ve searched and can’t seem to find a taller stacking header that says it’s for a Pi 4b and even if I could I don’t know how much I need with what fan, even if that’s the correct solution. Perhaps the fan could be plugged into a battery board, I don’t know if that is possible or not.
You may have issues with the Fan Hat, namely the software controlled fan speed and or soft shutdown function. The Hyperpixel uses all of the GPIO Pins and repurposes the functions of a lot of them.
This pretty well precludes any other hat from using the GPIO to talk to the Pi. If any of the hats you want to use use i2c etc to get info like CPU temp, they won’t work.
The battery Hat may work, if it can supply enough current to drive the Pi and display. Not a lot of info on what it needs from the Pi info wise.
If you try this both hats have to be stackable and I would go
Pi > Fan > battery > hyperpixel.
Thank you for the response. The only reason I was looking at that fan, or any hat fan, was so I could control when it ran to extend battery life. I don’t really know if that is a concern or not. Also there isn’t another way to get power to a fan that I can see. I could tap the fan off of the battery perhaps but then I’d have to be able to turn it off somehow.
You could run a regular stock fan off of the +5V. And it would stop when that 5V is removed after shutdown. Which your going to want to do if running from a battery. I use Adafruits PowerBoost 1000c in a few projects. It has an enable pin that will let you turn it off, no 5V out. I do that when not in use to keep the battery from slowly running dead. It won’t supply enough current for what your powering though.
Anything that gets its power from a LIPO battery is going to have to boost that up to 5V, and hopefully have a provision to turn the boost section off.
The +5V GPIO pins are one spot. Pins 2 and 4 are +5V and Pin 6 is ground. That’s where your battery hat feeds +5V into the Pi. It’s where the Hyperpixel gets its 5V from.
With stock normal setup +5V comes in to the Pi via the power supply, that same +5V also goes to those two GPIO pins to power Hats that need 5V for power. You can back power the Pi via those pins, which is what the battery hat does. It takes the LIPO’s 3.2 to 4 Volts and boost it to 5V.
You could also get the 5V from one of the USB ports. There should also be a couple of tests points on the bottom side of the Pi you could solder a wire to.
Or use a proto Hat on a stacking header.