The ATX Watchdog hat is here:
https://www.tindie.com/products/tomtibb ... -module-4/
It controls an ATX supply, and needs a switch connected to two of its pins for powering everything on. With a jumper (that isn't part of the kit, but has a mounting location present on the PCB), it will provide regulated 5V power to the pi via the GPIO header. (It will provide whatever max current the connected ATX power supply can do.)
But the pi 5 already has a power switch on the board, next to the LED and the PCIe flex connector. So if there's an externally available pair of contacts that this button shorts, then it's possible to connect that switch to the hat's power-button contacts, and use it to do both operations. (As long as the pullup resistor doesn't go to a voltage rail that will break one of the inputs that ends up connected to the button, like potentially on the micro on the watchdog board.)
Schematics (even partial ones) are not available for the pi 5 (...yet?), but I'm hoping someone can describe what the button connects to. It's a GPIO input on the pi 5's main microcontroller, but what does it pull up to, and is it also connected to the pair of contacts next to the battery backup connector? (The one in between the USBC port and HDMI-0.) Is it connected to other circuitry in order to trigger a pi startup and hard shutdown?
I might still need a separate power button anyway, but let's see if I can reuse the existing one first.
Thanks very much!
https://www.tindie.com/products/tomtibb ... -module-4/
It controls an ATX supply, and needs a switch connected to two of its pins for powering everything on. With a jumper (that isn't part of the kit, but has a mounting location present on the PCB), it will provide regulated 5V power to the pi via the GPIO header. (It will provide whatever max current the connected ATX power supply can do.)
But the pi 5 already has a power switch on the board, next to the LED and the PCIe flex connector. So if there's an externally available pair of contacts that this button shorts, then it's possible to connect that switch to the hat's power-button contacts, and use it to do both operations. (As long as the pullup resistor doesn't go to a voltage rail that will break one of the inputs that ends up connected to the button, like potentially on the micro on the watchdog board.)
Schematics (even partial ones) are not available for the pi 5 (...yet?), but I'm hoping someone can describe what the button connects to. It's a GPIO input on the pi 5's main microcontroller, but what does it pull up to, and is it also connected to the pair of contacts next to the battery backup connector? (The one in between the USBC port and HDMI-0.) Is it connected to other circuitry in order to trigger a pi startup and hard shutdown?
I might still need a separate power button anyway, but let's see if I can reuse the existing one first.
Thanks very much!
Statistics: Posted by bkadzban — Wed Apr 24, 2024 4:44 am