LM4F120XL

It is an older (2013) TI Launchpad board.

The CPU is a LM4F120H5QR 32-bit ARM Cortex M4F running at 80MHz. It has 256 kB flash memory and 32 kB SRAM.

Tools

Ubuntu 18.04 provides all necessary tools in the packages binutils-arm-none-eabi and lm4flash. All steps required to build and upload the code is in the launchpad-arm/Makefile. Just run make clean && make && make upload in one go.

Flashing the binary requires root privileges. See lm4tools for a solution.

Features

The RGB led is initialized and can be controlled with commands like red or black (turns it off).

> red \ turns on the red LED
 ok
> cyan blue yellow white
 ok
> black \ essentially turns off the LED
 ok
>

The CPU contains a timer that can be used for hardware assisted delays. It is started in the turnkey action and runs independently. The millisecond wait loop calls the word pause internally to make the multitasker happy. The loop terminates as soon as the minimum time is expired. This way, the actual delay may be slightly longer.

> delay-init
 ok
> 1000 ms \ waits 1 second
 ok
> 400000 us \ waits 400.000 microseconds
 ok
>

Basic flash write words are available:

• !i ( n addr – ) stores n at addr, with repeated writes to the same address only bit changes from 1 to 0 are done.
• c!i ( n addr – ) stores a single byte at addr. Same restrictions as !i
• w!i ( n addr – ) stores a 16-bit number at addr. Same restrictions as !i
• flashpageerase ( addr – ) erases the 1KB flash page at addr

Access to the data stored provide the usual @ and c@ operations.