Getting Started with RIOT and YARM

RIOT is a real-time multi-threading operating system that supports a range of devices that are typically found in the Internet of Things (IoT): 8-bit, 16-bit and 32-bit microcontrollers

This short tutorial shows the necessary steps to install all the tools used to develop applications based on RIOT, running on Yarm devices.

Please note : This procedure has been tested on a PC running Virtual Box VM, Host Win10 Pro 64, Guest Ubuntu 22.04 64.

Preparing your system for RIOT

First we download all the necessary tools

Development / Compile Tools

System compiler, linker, make etc.

sudo apt install build-essential

Toolchain

Arm cross-compiler for Yarm SAM L21E18B MCU.

sudo apt-get install gcc-arm-none-eabi

Git

Git version control tool.

sudo apt install git

Edbg

Command line utility for programming ARM-based MCUs through CMSIS-DAP SWD interface on Atmel-ICE.

cd ~ git clone https://github.com/ataradov/edbg.git cd edbg/ sudo cp 90-atmel-edbg.rules /etc/udev/rules.d/ sudo udevadm control --reload sudo apt-get install libudev-dev make

Install pip

Pip is the package installer for Python

sudo apt install pip

Install RIOT (Antonio Galea branch for yarm radio)

Thanks to Antonio, it is possible to use the ATA8510 chip of the Yarm on RIOT.

Download RIOT from Git

Main branch.

cd~ git clone https://github.com/ant9000/RIOT.git

Branch to yarm radio by Antonio Galea.

cd RIOT git checkout yarm_radio

Cross platform utilities

If developing on a 64 bit platform, install these to run 32 bit apps.

sudo apt-get install gcc-multilib sudo apt-get install g++-multilib

Install python module pySerial

This module is used by pyterm, a python based serial terminal, included in the RIOT repository

pip install pyserial

Install python module twisted

"twisted is an event-based framework for internet applications, supporting Python 3.6+."

pip install twisted

First RIOT test application

Once the installation is completed, let's check that everything was properly done by running the following test.

Setup programming connections

First of all we must prepare the right setup to program the YARM.

Connections to PC, Atmel-ICE, YARM-2_ICE and YARM DEV are shown in the following picture

Make sure the switch on the YARM-2-ICE is set to SAM

Create a workspace folder

cd~ mkdir workspace

In workspace create a first test folder

cd workspace mkdir riot_first cd riot_first

Create and save this Makefile

APPLICATION = Task01
BOARD = yarm
RIOTBASE = /home/$(USER)/RIOT
CFLAGS += -DDEVELHELP
QUIET ?= 1
USEMODULE += shell
USEMODULE += shell_commands
USEMODULE += ps
include $(RIOTBASE)/Makefile.include

Create and save this main.c file

#include <stdio.h>
#include <string.h>
#include "shell.h"

int main(void)

{
int j;
int i=0;

    for(j=0;j<25500000;j++);
    printf("This is Task-01");
    while(1)
    {
        for(j=0;j<5500000;j++);
        printf("Running  %8x - %2x\n",i, i%0x10);
        i++;
    }
    return 0;
}

Compile, flash

The following command will compile and link the source code, flash the MCU, then execute the terminal emulator

make all flash term

A successful compile and link procedure looks like this :

Building application "Task01" for "yarm" with MCU "saml21". "make" -C /home/user/RIOT/boards/yarm "make" -C /home/user/RIOT/core "make" -C /home/user/RIOT/cpu/saml21 "make" -C /home/user/RIOT/drivers "make" -C /home/user/RIOT/sys "make" -C /home/user/RIOT/drivers/periph_common "make" -C /home/user/RIOT/sys/auto_init "make" -C /home/user/RIOT/sys/event "make" -C /home/user/RIOT/sys/isrpipe "make" -C /home/user/RIOT/cpu/cortexm_common "make" -C /home/user/RIOT/sys/newlib_syscalls_default "make" -C /home/user/RIOT/sys/auto_init/usb "make" -C /home/user/RIOT/cpu/sam0_common "make" -C /home/user/RIOT/sys/pm_layered "make" -C /home/user/RIOT/cpu/saml21/periph "make" -C /home/user/RIOT/sys/ps "make" -C /home/user/RIOT/sys/shell "make" -C /home/user/RIOT/sys/shell/commands "make" -C /home/user/RIOT/sys/tsrb "make" -C /home/user/RIOT/sys/usb/usbus "make" -C /home/user/RIOT/cpu/sam0_common/periph "make" -C /home/user/RIOT/cpu/cortexm_common/periph "make" -C /home/user/RIOT/sys/usb/usbus/cdc/acm text data bss dec hex filename 23432 136 5856 29424 72f0 /home/user/workspace/riot_first/bin/yarm/Task01.elf

Then the MCU is flashed

/home/user/RIOT/dist/tools/edbg/edbg --target saml21 --verbose --file /home/user/workspace/riot_first/bin/yarm/Task01.bin --verify || /home/user/RIOT/dist/tools/edbg/edbg --target saml21 --verbose --file /home/user/workspace/riot_first/bin/yarm/Task01.bin --verify --program Debugger: ATMEL Atmel-ICE CMSIS-DAP J41800017751 01.24.007E (SJ) Clock frequency: 16.0 MHz Target: SAM L21E18B (Rev C) Verification....... at address 0x4e0 expected 0x88, read 0x84 Error: verification failed Debugger: ATMEL Atmel-ICE CMSIS-DAP J41800017751 01.24.007E (SJ) Clock frequency: 16.0 MHz Target: SAM L21E18B (Rev C) Programming................................................................................................ done. Verification................................................................................................ done.

Entering terminal and monitoring program execution

sleep 2 /home/user/RIOT/dist/tools/pyterm/pyterm -p "/dev/ttyACM0" -b "115200" 2023-06-01 16:07:58,007 # Connect to serial port /dev/ttyACM0 Welcome to pyterm! Type '/exit' to exit. 2023-06-01 16:07:59,036 # Running 4 - 4 2023-06-01 16:07:59,036 # Running 5 - 5 2023-06-01 16:07:59,112 # Running 6 - 6 2023-06-01 16:07:59,576 # Running 7 - 7 2023-06-01 16:08:00,040 # Running 8 - 8 2023-06-01 16:08:00,503 # Running 9 - 9 2023-06-01 16:08:00,967 # Running a - a 2023-06-01 16:08:01,431 # Running b - b 2023-06-01 16:08:01,894 # Running c - c 2023-06-01 16:08:02,358 # Running d - d 2023-06-01 16:08:02,822 # Running e - e 2023-06-01 16:08:03,285 # Running f - f 2023-06-01 16:08:03,748 # Running 10 - 0 2023-06-01 16:08:04,212 # Running 11 - 1 /exit 2023-06-01 16:08:04,337 # Exiting Pyterm