vortex314 / tiva-rs

Using stellaris launchpad modules as an USB coupled IoT. LM4F120h5QR

First project on Stellaris Launchpad using Rust

This is a simple project for the Stellaris Launchpad using Rust.

[tm4c123x-hal](https://github.com/rust-embedded-community/tm4c-hal) is used to access the hardware. ## Requirements for an embedded actor model - async/await and timers - usable on std and no_std - actors shouldn't be aware of each other existance - wiring happens outside actor - actors should be able to be used in a non-embedded environment - actors should be able to be used in a multi-threaded environment - fast and efficient use of cpu resources - suport buffering of messages - actor should be internally handling, one message at a time ## Requirements - communicate via serial to serial2redis - serial protocol is JSON or CBOR - serial protocol should be consumable by a USB client inside browser

References

• Tutorial stellaris - pinout
• Datasheet
• Product Sheet
• Stellaris Launchpad board
• StellarisWare User Guide
• Olimex UEXT extension board
• Olimex Stellaris UEXT product page
• Olimex Stellaris UEXT Schematic

Too look at

• probe usage and embassy example
• embassy on ESP32
• async in embedded driver
• general rust async

Embassy ( on hold )

RUST setup embassy

rustup target add thumbv7em-none-eabihf
rustup toolchain install nightly
rustup default nightly

Encountered issues

• most JSON serializer use std
• embassy on a not officially supported board is a bit of a pain to get working
• embassy timers drags in a lot of dependencies , if you don't have a stm32 or nrf52 board you are basically out of luck

RTIC

• stopped this one,as the programming model just deviates too much from the normal rust async model

spin_on

• very simple, but also very limited

std on microcontroller

• Excellent article

rustup target add thumbv7em-none-eabihf
rustup +nightly target add thumbv7m-none-eabihf
# build
cargo +nightly run --release
# list all targets
rustc --print target-list
cargo +nightly build -Z build-std=std,panic_abort --target thumbv7em-none-eabihf

This works fine, but the resulting binary is 247kB in size for an empty program, which is a bit too much for a microcontroller with 256KB of flash.

• Build with std and panic_abort

   text    data     bss     dec     hex filename
 247692      28      56  247776   3c7e0 target/thumbv7em-none-eabihf/debug/tiva-rs

• Build with no_std

   text    data     bss     dec     hex filename
  36480       0       4   36484    8e84 target/thumbv7em-none-eabihf/debug/tiva-rs

Build with

GDB cheat sheet

• (gdb) l - list source code
• (gdb) b - set breakpoint
• (gdb) r - run
• (gdb) c - continue
• (gdb) n - next - code line by line
• (gdb) s - step - step into function and next instruction cpu
• (gdb) p - print
• (gdb) bt - backtrace
• (gdb) i r - info registers
• (gdb) i r r0 - info register r0
• (gdb) i r pc - info register pc
• (gdb) i r sp - info register sp
• (gdb) i r lr - info register lr
• (gdb) jump reset - jump to reset
• (gdb) jump main - jump to main
• (gdb) x/10x $sp - examine stack
• (gdb) x/10x $pc - examine program counter
• (gdb) info break - list breakpoints
• (gdb) delete breakpoints - delete all breakpoints
• (gdb) x/i $pc - examine instruction at program counter
• (gdb) info functions - list all functions
• (gdb) info variables - list all variables