General • Re: Bare-metal Bit Banging GPIO (AQA Assembly style)

There is quite a lot of work I need to do here but for now I am adapting the files in Life-With-David's repository

He has created a linker script and it uses elf2uf2 which simplifies things for me a lot in terms of allowing students to deploy their programs and it's allowing me to work on resources to teach about differences between AQA's theoreticla instruction set and the real ARM version it's based on, 32 bit addresses being accessible via 16 bit instructions and so forth...

• I will go through the RP2040 architecture and bus.
  Split up the reset and assign GPIO to SIO and blink the LED on 25 as theoretical paper based activities.
  I'll provide an adapted version of Life-with-David's repository so they can have a working assembly program of that program with linker script at their disposal.

They will get a Pico with a 7 segment LED display connected to GPIO 0 to 6 and their task will be to write a number, make a countdown or blink the LEDs in a circle. Obvs. displaying a number leads on to more useful stuff later.

Why did ARM create a 16 bit version of their normal 32 bit instructions? The interweb says

For Thumb code, more instructions can be fetched at the same time, which requires less stalls.

but why is that?

Statistics: Posted by morphy_richards — Thu Jul 04, 2024 12:14 pm

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