07-29-2020, 01:24 AM
(07-28-2020, 10:52 PM)KC9UDX Wrote: If you want to go low level, I wouldn't use Linux at all. I'd start out with Minix or NetBSD.
(07-29-2020, 12:41 AM)Subsentient Wrote:(07-28-2020, 10:14 PM)overdrawnfettuccine Wrote: How sure are you about that? As the solo programmer I was able to check the status of the SIM card, connect to 4g cell towers, check the signal strength, receive text messages, react to them, store them on the phone, send text messages and pull up GPS information with GLONASS. I specifically remember using AT+CMGF and wondering why my PDU text is not correct and switching to text because it was suitable for our application. It's not too hard
The problem you'll have is getting the system to boot that far. Take a look at the device tree structure for Linux's implementation of the pinephone. This isn't an ATTiny85 where you can just fiddle registers directly and run on bare metal at kernel-level with almost no setup. For example, look at the U-Boot implementation, and that's just to get the kernel executed. U-Boot also has its own device tree implementation. ARM devices are a nightmare to get booted from ground zero and doing anything useful, just in general. If the PinePhone had ACPI/EFI it would be different.
I'm not saying it can't be done, but it's going to be a LOT more difficult than hacking on an arduino or ATMega AVR MCU, and even much more difficult than an x86 PC.
I have to ask, why would you want to go to all that trouble, when anything one man can write would be a vast underutilisation of the PinePhone's Cortex-A53 CPU? I run full desktop-grade XFCE and desktop Firefox etc on mine, and that's my daily driver.
Oh I had no idea there were many hoops to jump through. I thought it'd be fun to program a device that only runs my code with a touchscreen and wifi