1.
Running JavaScript
on microcontrollers
Volodymyr Shymanskyy

2.
What systems are we talking about?
System architecture
Engines overview
Benefits
Used on production?
Demo!

3.
V8
SpiderMonkey
JavaScriptCore
Chakra
JavaScriptCoreV8 ???

4.
Raspberry Pi Zero W
VoCore v2
Intel Joule

5.
Library
Processor(s) Memory Devices
Kernel
Drivers
Supervisor
Application
Hardware
Library Lib
Library L
Program
Program
Program
ProgramNode.js
SYSTEM OVERVIEW

6.
ARDUINO UNO
CPU 16 MHz [8-bit]
Flash 32 Kb
RAM 2 Kb
Bare metal (no OS)

7.
ESP8266 ~ $1.8
CPU 160 MHz
Flash 4 Mb
RAM 128 Kb
+ WiFi
ESP32 ~ $4.5
CPU 2x 240 MHz
Flash 4 Mb+
RAM 520 Kb
+ WiFi
+ Bluetooth 4.2
+ crypto engine, etc.
nRF52832 ~ $8.5
CPU 64MHz
Flash 512 Kb
RAM 64 Kb
+ Bluetooth 5
+ 6LoWPAN
+ NFC
+ Low Power

8.
HOW MUCH IS ENOUGH?
Engine License Binary RAM
Google V8 BSD 3-clause >8M >24M
JavaScriptCore LGPL 2.0 >4M >8M
Duktape MIT 100k 30k
V7 GPL v2.0 70k 1k
mJS GPL v2.0 50k 1k
JerryScript Apache 2 200k 64k
Espruino MPL v2.0 128k 8k

9.
JS Library
Processor(s) Memory Devices
RTOS Drivers
Application
Hardware
JS Lib JS
JS Library
JS App
JS engine
Supervisor
SYSTEM OVERVIEW

10.
JS Library
Processor(s) Memory Devices
JS engine
Drivers
Supervisor
Application
Hardware
JS Lib JS
JS Library
JS App
SYSTEM OVERVIEW

11.
Bluetooth Key Tag ~ $12

12.
DISASSEMBLING

13.
SOC: nRF51822
● Single chip 2.4 GHz multi-protocol device
● 32-bit ARM Cortex M0 CPU core
● 256k Flash
● 32k RAM
● Bluetooth Low Energy 4.0
● Thread safe and run-time protected
● Event driven API

14.
+3.3v IO CLK GND

15.
● Feature-rich JS engine
● Declares nRF51822 support
(as well as many other MCUs)
● Supports Bluetooth
● Has an IDE
● Auto-minifies JS
● Provides REPL via bluetooth
● & I had some prev. experience ;)

16.
BUILD IT
1. Get Espruino release from github
2. Install gcc-arm-none-eabi-5_4-2016q3 toolchain
3. Build:
BOARD=NUT2 RELEASE=1 make
-> hex file is produced
4. Flash it to the board
.:[ complete instructions ]:.
ST-Link V2 ~ $2

17.
LET’S CODE
LED1.write(1); /* Turn led ON */
LED1.write(0); /* Turn led OFF */
function toggle() {
state = !state;
LED1.write(state);
}
/* Start timer */
setInterval(toggle, 500)
/* Output frequency: 1000 hz square wave */
analogWrite(D30, 0.5, { freq: 1000 } )

18.
function buzz(f, duration) {
analogWrite(D30, 0.5, { freq: f } );
setTimeout(function() {
pinMode(D30, 'input');
}, duration);
}
let mario_freq = new Uint16Array([330,330,0,330,0,262,330,0,392,0,0,196,0,0, ...]);
let mario_temp = new Uint8Array([80 ,80,80,80,80,80,80,80,80,80,40,80,80,40, ...]);
let pos = 0, tmr = -1;
function step() {
let freq = mario_freq[pos];
if (freq === undefined)
return stop();
let temp = 10000/mario_temp[pos];
changeInterval(tmr, temp);
buzz(freq, temp);
pos++;
}
function stop() {
if (tmr >= 0) {
buzz(0);
clearInterval(tmr);
tmr = -1;
}
}
function play_mario() {
stop();
pos = 0;
tmr = setInterval(step, 0);
}
Not too much simplified ;)

19.
DEMO
(plays Mario theme)

20.
● Platform abstraction
● Interactive, dynamic execution
● Event-Driven model
● Semi-automatic Power Management
● Perfect for prototyping
● Security
BENEFITS

21.
IN PRODUCTION
Python, actually

22.
Puck.js
.:[nRF52]:.
M5stack
.:[ESP32]:.
OUT OF THE BOX

23.
.:[ Q & A ]:.

24.
Volodymyr Shymanskyy
Entrepreneur, Software & Hardware Developer, Trainer
Co-Founder of Blynk, Hackerspace Coordinator
● Lots of projects
● 10+ years in IT, 8 in outsourcing and embedded
● Master’s degree in Cybernetics
@ National Taras Shevchenko University of Kyiv
> facebook > LinkedIn > vshymanskyi@gmail.com
Disclaimer: these brands are not affiliated with current presentation or it’s topic

25.
.:[ additional materials ]:.

26.
TI CC2650 ~ $8.5
CPU 48MHz
Flash 128 Kb
RAM 28 Kb
+ Bluetooth 4.2
+ 6LoWPAN
EZ-BLE™ PSoC® ~ $10
CPU 48MHz
Flash 128 Kb
RAM 16 Kb
+ Bluetooth 4.1
TI CC3220 ~ $15.6
CPU 80 MHz
Flash 1 Mb
RAM 256 Kb
+ WiFi
+ secure + low power

27.
OpenOCD: Backup
source [find interface/cmsis-dap.cfg]
set WORKAREASIZE 0
source [find target/nrf51.cfg]
openocd_ble_nano.cfg:

28.
OpenOCD: Backup
$ openocd -f openocd_ble_nano.cfg
Open On-Chip Debugger 0.9.0 (2015-09-02-10:42)
Licensed under GNU GPL v2
For bug reports, read
http://openocd.org/doc/doxygen/bugs.html
Info : only one transport option; autoselect 'swd'
cortex_m reset_config sysresetreq
adapter speed: 1000 kHz
Info : CMSIS-DAP: SWD Supported
Info : CMSIS-DAP: Interface Initialised (SWD)
Info : CMSIS-DAP: FW Version = 1.0
Info : SWCLK/TCK = 0 SWDIO/TMS = 1 TDI = 0 TDO = 0 nTRST = 0 nRESET = 1
Info : CMSIS-DAP: Interface ready
Info : clock speed 1000 kHz
Info : SWD IDCODE 0x0bb11477
Info : nrf51.cpu: hardware has 4 breakpoints, 2 watchpoints

29.
OpenOCD: Backup
$ telnet localhost 4444
Trying 127.0.0.1...
Connected to localhost.
Escape character is '^]'.
Open On-Chip Debugger
> flash list
{name nrf51 base 0 size 0 bus_width 1 chip_width 1} {name nrf51 base 268439552 size 0
bus_width 1 chip_width 1}
> flash banks
#0 : nrf51.flash (nrf51) at 0x00000000, size 0x00040000, buswidth 1, chipwidth 1
#1 : nrf51.uicr (nrf51) at 0x10001000, size 0x00000100, buswidth 1, chipwidth 1
> flash info 0
nRF51822-QFAA(build code: H0) 256kB Flash
…
> dump_image backup.bin 0x00000000 0x00040000
dumped 262144 bytes in 16.601297s (15.420 KiB/s)
http://openocd.org/doc/html/Flash-Commands.html

30.
OpenOCD: Restore
$ telnet localhost 4444
Trying 127.0.0.1...
Connected to localhost.
Escape character is '^]'.
Open On-Chip Debugger
> reset halt
target state: halted
target halted due to debug-request, current mode: Thread
xPSR: 0xc1000000 pc: 0x000006d0 msp: 0x000007c0
> program backup.bin verify reset exit 0x00000000
...