Presentation about Mbed OS, the community and how to engage with >400 contributors. Given at FOSS North in Gothenburg.

1. 17,000 contributions
in 32K of RAM
Jan Jongboom, Arm
FOSS North
9 April 2019

2. Jan Jongboom
Principal Developer Evangelist
jan.jongboom@arm.com

4. © 2019 Arm Limited 4
Processor shipments (by Arm)
Arm: the industry’s Architecture of Choice
>95% the world’s
smartphones are
based on Arm
22 years
4 years
4 years
20171991 2013 2021
50 billion
chips shipped
50 billion
chips shipped
100 billion
chips expected to ship
>50% of Arm chips
shipped in FYI6 (17+bn)
into embedded devices

5. © 2019 Arm Limited 5
Majority of these do not go into personal computers

6. © 2019 Arm Limited 6
But rather in these

8. © 2019 Arm Limited 8
Microcontrollers
Small (1cm²)
Cheap (~1$)
Efficient (standby: 0.3 μA)
Everything in one package
Slow (max. 100 MHz)
Limited memory (max. 256K RAM)
Downsides
8 cm

9. © 2019 Arm Limited 9
Microcontroller vs. application processor
No Memory Management Unit (MMU)
No BIOS, much simpler boot sequence
Waking up: <10 us. from sleep mode, <10 ms. from deep sleep mode
Real-time
General-Purpose Input/Output ports (GPIO)
But much less powerful

10. © 2019 Arm Limited 10
Development board

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Not a microcontroller!

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An operating system
for microcontrollers

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Many software parts
Bootloader
Asymmetric crypto
Storage driver
Resilient filesystem
Advanced
networking stack
Radio drivers
FlashIAP
Sleep managementRTOS

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Arm Mbed
A free, open source Platform OS targeting IoT end node devices
Mbed
OS
Cortex-M
RTOS
kernel
Portable
drivers
Integrated
security
IoT
connectivity
Device
management
Development
tools
Developer
community
Partner
ecosystem
170 development boards
LoRa, BLE, Cellular, Wi-Fi, etc.
14

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Open source and community built
325,000 developers
70+ partners
Apache 2.0 licensed
https://os.mbed.com

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Contributions over time
Arm
Partners
Community

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Release schedule
Feature Releases
• Bringing new and
enhanced features every
3 months
Patch Releases
• Adding new partner
target support and
delivering bug fixes
every 2 weeks
2017 2018 2018
A regular release train for effectively supporting developers and partners
1980
Mbed OS 5.7
1980
Mbed OS 5.8
1980
Mbed OS 5.9
1980
Mbed OS 5.10

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Managing the community

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Mbed OS developer community

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Community leaders, partners, and support team

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Commercial support

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Community engagement through Office Hours

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Q&A is vital part of Office Hours

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Documentation lives on GitHub

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Continuous integration

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Tests
Mbed OS 5.6
~500 functional tests
System tests
Mbed OS 5.10
~1150 functional tests
System tests
Host unit tests
Fast model
More than 100,000 tests cases run per day
Farm of over 800 devices
~40,000 hours of testing for Mbed OS 5.10
release

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Features

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Components

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Tooling
Online compiler Mbed CLI Offline IDE
C:> mbed

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https://os.mbed.com/platforms

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Porting
Application
Mbed C++ HAL (generic)
Mbed C HAL (vendor specific)
Peripherals
Thread safety, sane API
Ties in with HAL

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Blinky, C++ to peripheral
#include "mbed.h"
DigitalOut led(LED1);
int main() {
while (1) {
led = !led;
wait_ms(500);
}
}

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Blinky, C++ to peripheral
Cortex-M boot sequence explanation: https://www.youtube.com/watch?v=3brOzLJmeek
// Mbed C++ HAL
DigitalOut::write(int value) {
gpio_write(&gpio, value);
}
// Mbed C HAL (implemented by vendor)
void gpio_write(gpio_t *gpio, int value) {
if (value == 1) {
0x40200000 = 1U << gpio->pin;
}
else {
0x40200004 = 1U << gpio->pin;
}
}

35. © 2019 Arm Limited 35
Porting

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Low power
Providing Low Power
features & optimizations
required for IoT devices
Low Power
Modes
Power Mode
Tools
Tickless Scheduler

37. © 2019 Arm Limited 37
Idle (no sleep)

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Deep sleep

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Networking stacks
LwIP (IPv4, IPv6, PPP)
Nanostack (IPv6, 6LoWPAN, Thread)
Certified 6LoWPAN over 802.15.4 stack
Certified LoRaWAN stack
BLE 5.1 stack

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Other features
RTOS included (KEIL RTX)
Event scheduler (Mbed Events)
Filesystems included (FAT and LittleFS)
Device statistics
Memory tracing supported
40

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Getting started

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https://os.mbed.com/platforms

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Connecting a moisture sensor
Signal
Power
Ground
A3
3.3V
GND

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Online Compiler
https://ide.mbed.com/compiler

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Mbed Studio
A desktop IDE designed for Mbed OS, suitable for professionals and hobbyists alike.
✓ Arm Compiler 6
✓ Import Mbed programs from
os.mbed.com and GitHub
✓ C/C++ code completion and inspection
✓ Mbed library management
✓ Build, run and debug connected
platforms
✓ Support for Windows, Linux and Mac OS
✓ Updated online IDE based on the same
framework

46. © 2019 Arm Limited 46
Reading from the moisture sensor
AnalogIn moisture(A3);
while (1) {
float value = moisture.read();
printf("Moisture value is %fn", value);
wait_ms(500);
}

47. © 2019 Arm Limited 47
Flashing through drag-n-drop
Compile
Drag .bin file to your board (mounts as mass-storage device)
Automatically flashes
Attach serial monitor to see progress

48. © 2019 Arm Limited
Mbed Labs

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http://mbed.com/js

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Recap
1. Most computers are neither in your pocket nor on your desk
2. A constraint device does not have to be scary, actually it can be fun
3. Mbed OS is the platform to help you with this!
4. Come and join our community at https://os.mbed.com !

54. © 2019 Arm Limited 54
https://os.mbed.com
Slides: http://janjongboom.com
Thank you!