RubyConf2013: "How to control physical devices with mruby" by Yamanekko

1. How to control
physical devices
with mruby
RubyConf 2013
Team Yamanekko
Yurie Yamane / Masayoshi Takahashi

2. Demo
Blinking 4 LEDs
on STM32F4 Discovery
(using Timer)

3. DEMO (STM32F4 Discovery)
●
blinking LED
Green on -> Orange on -> Red on -> Blue on ->
Green off -> Orange off -> Red off -> Blue off -> ...

4. Contents
●
Demo (STM32F4 Discovery)
●
Introduction
●
What's mruby
●
7 steps to use mruby
●
Demo (Raspberry Pi)
●
Another Demo (STM32F4 Discovery)

5. Who are we?
●
やまね ゆりえ
●
高橋征義
(Yurie Yamane)
(Masayoshi Takahashi)

6. Who are we?
Team Yamanekko

7. Independent E-Book Publisher
Tatsu-zine Publishing Inc.
http:/
/tatsu-zine.com/

8. This session is supported by
http:/
/ruby-no-kai.org/

9. members of asakusa.rb

10. Who are we?
●
Not professional Embedded
programmers
–
it's our hobby project
●
not made e-book reader yet

11. Our goals
“embedded programming
for everyone without hassle”

12. Our talks
RubyConf2012

13. Our talks
RubyConf.tw 2012

14. Our talks
OSDC.tw 2013

15. Our talks
http://www.flickr.com/photos/igaiga/8564676738/
Ôedo RubyKaigi 03

16. Embedded is hard??
●
small memory
●
RTOS or no OS
●
no STDIO
●
cross compile C/C++/Asm
●
cross debugger with ICE

17. Embedded is hard??
●
small memory
●
RTOS or no OS
●
no STDIO
●
cross compile C/C++/Asm
●
cross debugger with ICE

18. http://mrb.h2so5.net/

19. What's mruby?
●
“yet another implementation
of Ruby”
–
not a new language nor
variant

20. CRuby vs mruby
●
mruby is not “an application”
●
mruby is “a part”
–
embedded into other application
●
–
webserver, editor, game, ...
embedded into other systems
●
robot, router, vending machine, ...

21. mruby's feature
(1)
embeddable
(2)
configurable
(3)
pluggable

22. (1) embeddable
CRuby app
mruby app
*.rb
*.rb
(bytecode)
libmruby.a
/usr/bin/ruby
C/C++ app

23. CRuby
*.rb (your code)
*.rb (stdlib)
Gems
/usr/bin/ruby

24. Bytecode
(C String)
Bytecode
(C String)
mruby
*.rb (your code)
*.rb (stdlib) mrbgems
libmruby.a
mruby core
C/C++

25. (2) configurable
●
mruby has many #define macros to configure
–
–
using NaN boxing or not
–
●
float or double as Float object
default size of heap, pool, khash, ...
You can change them at compile time

26. #define in mrbconf.h
●
MRB_USE_FLOAT
●
MRB_IREP_ARRAY_INIT_SIZE
●
MRB_INT64
●
KHASH_DEFAULT_SIZE
●
MRB_NAN_BOXING
●
POOL_ALIGNMENT
●
MRB_ENDIAN_BIG
●
POOL_PAGE_SIZE
●
MRB_FUNCALL_ARGC_MAX
●
MRB_STR_BUF_MIN_SIZE
●
MRB_HEAP_PAGE_SIZE
●
MRB_PARSER_BUF_SIZE
●
MRB_USE_IV_SEGLIST
●
ENABLE_DEBUG
●
MRB_IVHASH_INIT_SIZE

27. (3) pluggable
●
mruby has mrbgems like RubyGems
●
mrbgems in C are linked statically
●
some functions in CRuby are
provided as gem
–
you can choose which is added /
removed

28. standard mrbgems
●
●
●
●
●
●
●
●
●
●
mrbgems/mruby-array-ext
mrbgems/mruby-enum-ext
mrbgems/mruby-eval
mrbgems/mruby-exit
mrbgems/mruby-fiber
mrbgems/mruby-hash-ext
mrbgems/mruby-math
mrbgems/mruby-numeric-ext
mrbgems/mruby-object-ext
mrbgems/mruby-objectspace
●
●
●
●
●
●
●
●
●
●
mrbgems/mruby-print
mrbgems/mruby-proc-ext
mrbgems/mruby-random
mrbgems/mruby-range-ext
mrbgems/mruby-sprintf
mrbgems/mruby-string-ext
mrbgems/mruby-struct
mrbgems/mruby-symbol-ext
mrbgems/mruby-time
mrbgems/mruby-toplevel-ext
you can remove them all

29. 7 steps to use mruby
●
choose your target board
●
setup development environments
●
write application
●
cross build
●
transfer binary to the board
●
cross debugging
●
it works!

30. 7 steps to use mruby
●
choose your target board
●
setup development environments
●
write application
●
cross build
●
transfer binary to the board
●
cross debugging
●
it works!

31. Our targets crieteria
●
easy to buy around the world
–
●
don't use apps depending on OSs or environments
–
●
some are hard outside Japan :(
FLOSS tools are better
a bit large memory that mruby can run on
–
> 64KB is MUST, > 1MB is BETTER

32. (1) STM32F4 Discovery
●
ARM (Cortex M4)
●
1MB Flash, 192KB RAM
●
●
8LEDs, 2Buttons, MEMS
Accelerometer etc.
on board STLINK
http://www.st.com/web/catalog/tools/FM116/SC959/SS1532/PF252419

33. (2) Raspberry Pi
●
ARM (arm1176jzf-s)
●
256/512MB RAM
●
SD card
●
700mA (3.5W)
●
JTAG

34. ARM11 & Cortex-M4
Raspberry Pi
STM32F4
http://www.emcu.it/CortexFamily/CortexFamily.html

35. **NOTICE**
●
We do not use OS on Raspberry Pi
–
no raspbian nor other Linux/Unix

36. Why no OS (bare metal)?
●
same as STM32F4 Discovery
–
●
We want to use Raspberry Pi like MCU, not PC
–
–
●
STM32F4 Discovery is used without OS
just as MCU with HUGE memory
If using Linux, even CRuby can work on
Raspberry Pi :-/
Bare metal programming is fun :-)

37. bare metal RasPi Programming
●
dwelch67's github repos is incredibly useful
–
–
https:/
/github.com/dwelch67/raspberrypi
everything we need is here

38. apps
STM32F4d architecture
main
(c)
Ruby code (*.rb → bytecode)
mruby core (in c)
mrbgems for STM32F4 Discovery
libmruby.a
CMSIS
Core Peripheral
Device Peripheral
Functions
Functions
Peripheral Register & Interrupt Vector Definitions
MCU
libc (newlib), syscalls
Cortex
MCU
Systick
timer
NVIC
interrupt controller
other
peripherals

39. Raspberry Pi architecture
Ruby code (*.rb → bytecode)
apps
mruby core
mrbgems for Raspberry Pi
libmruby.a
libc (newlib), syscalls
SoC
vectors.s
ARM11
MCU
Timer
Other BCM2385
peripherals

40. 7 steps to use mruby
●
choose your target board
●
setup development environments
●
write application
●
cross build
●
transfer binary to the board
●
cross debugging
●
it works!

41. Our Development Environment
●
Cross Compiler: GNU tool chain
●
IDE: Eclipse CDT + our original plugin
●
Debugging :
–
STLINK (for STM32F4d)
–
JTAG (for RasPi)

42. cross compiler for STM32F4
GNU Tools for ARM Embedded Processors
(https:/
/launchpad.net/gcc-arm-embedded)

43. cross compiler for RasPi
●
'GNU Tools for ARM Embedded Processors' is...
–
–
“1. ARM11 is not our primary targets, so those tools are not
tested on such targets.”
“Thus I don't recommend this tool chain for Raspberry Pi.”
https://answers.launchpad.net/gcc-arm-embedded/+question/227876
●
So we use GNU Tools built by our own.
https://github.com/dwelch67/build_gcc/blob/master/build_arm

44. How to debug with STM32F4d
PC
STM32F4d
stlink
STLINK
USB cable
gdb
for arm
Eclipse
arm-none-eabi-gdb
stlink: https:/
/github.com/texane/stlink

45. How to debug with RasPi
PC
RasPi
armjtag
OpenOCD
USB and
JTAG cable
gdb
for arm
Eclipse
arm-none-eabi-gdb
OpenOCD: http:/
/openocd.sf.net/
armjtag:
https:/
/github.com/dwelch67/raspberrypi/tree/master/armjtag

46. JTAG debugger (hardware)
ARM-USB-TINY-H
●
connect ARM via USB
https://www.olimex.com/Products/ARM/JTAG/ARM-USB-TINY-H/

47. JTAG debugger (hardware)
●
connect JTAG cable
and RasPi
●
Use 6pins only (and GND)
https:/
/www.olimex.com/Products/ARM/_resources/arm-jtag-layout.gif

48. JTAG debugger (software)
●
http://openocd.sourceforge.net/
You can do fash
programming
and GDB
debugging with
OpenOCD.

49. armjtag
https:/
/github.com/dwelch67/raspberrypi/tree
/master/armjtag
“an alternate bootloader”
“The ARM11 on the Raspberry Pi has a jtag
based debug port for software development.”

50. are you tired?

51. 7 steps to use mruby
●
choose your target board
●
setup development environments
●
write application
●
cross build
●
transfer binary to the board
●
cross debugging
●
it works!

52. write application
●
write Ruby code
●
write mrbgems
●
write C code

53. Including Ruby code in mruby
●
As source code of Ruby
Human readable
As Byte code
–
●
–
Machine readable

54. Including Ruby code in mruby
●
As source code of Ruby
Human readable
As Byte code
–
●
–
Machine readable

55. hello world in mruby (1)
#include
#include
#include
#include
<stdlib.h>
<stdio.h>
<mruby.h>
<mruby/compile.h>
int main(void)
{
mrb_state *mrb = mrb_open();
char code[] = "p 'hello world!'";
mrb_load_string(mrb, code);
mrb_close(mrb);
return 0;
}

56. hello world in mruby (1)
mrb_state *mrb = mrb_open();
char code[] = "p 'hello world!'";
mrb_load_string(mrb, code);
mrb_close(mrb);

57. Including Ruby code in mruby
●
As source code of Ruby
Human readable
As Byte code
–
●
–
Machine readable

58. hello world in mruby (2)
mrb_state *mrb = mrb_open();
const uint8_t bcode[] = {
0x52,0x49,0x54,0x45,0x30,0x30,0x30,
(… byte byte byte …)
0x00,0x00,0x00,0x00,0x08,
};
mrb_load_irep(mrb, bcode);
mrb_close(mrb);

59. hello world in mruby (2)
$ cat hello.rb
p 'hello world!'
$ ./bin/mrbc -Bbcode hello.rb
$ cat hello.c
#include <stdint.h>
const uint8_t foo[] = {
0x52,0x49,0x54,0x45,0x30,0x30,0x30,0x31,0x
b9,0x71,0x00,0x00,0x00,0x65,0x4d,0x41,
(…)
0x00,0x00,0x00,0x00,0x08,
};
$

60. mrb_open
Create and initialize new mruby VM
Usage:
mrb_state *mrb = mrb_open();

61. mrb_close
release mruby VM
Usage:
mrb_close(mrb);

62. mrb_load_irep
load mruby bytecode and execute.
Usage:
mrb_load_irep(mrb, bcode);

63. mruby API
In include/mruby.h
and include/mruby/*.h
※all API has mrb_state at 1st arg.
ex.
mrb_load_string(mrb, code);

64. mrbgems
●
●
●
“mruby gems” by bovi
library packaging system like
RubyGems
static linked with compile time

65. mrbgem.rake
MRuby::Gem::Specification.new(
'mruby-rs-led') do |spec|
spec.license = 'MIT'
spec.authors = 'yamanekko'
end

66. minirake
mruby has minirake full source
minimal rake clone by masuidrive
– you do not have to install rake even if
using Ruby 1.8
mrbgems and mruby itself are built by
minirake
–
●

67. Why (mini)rake
●
old mruby used CMake
●
but mruby build system became complex
–
–
get source code from github
–
●
build mrbgems (Ruby and C)
support gem bundle (gembox)
we want to write them in Ruby

68. build_config.rb
●
Ruby (not mruby) script
Execute in host machine at building time
DSL to build mruby
–
●
●
Load from Rakefile

69. Default (minimal) build_config.rb
MRuby::Build.new do |conf|
toolchain :gcc
conf.gembox 'default'
end

70. DEMO (Raspberry Pi)
●
blinking LED (like STM32F4 Discovery)
Green on -> Orange on -> Red on -> Blue on ->
Green off -> Orange off -> Red off -> Blue off

71. Ruby Code (init)

72. Ruby Code (blink)

73. 7 steps to use mruby
●
choose your target board
●
setup development environments
●
write application
●
cross build
●
transfer binary to the board
●
cross debugging
●
it works!
demo
using Eclipse

74. Install MrubyTools plugins

75. Install MrubyTools plugins

76. create mruby project
●
cloned from https:/
/github.com/mruby/mruby

77. CREATE CUSTOM mrbgems
●
create new mrbgem to control STM32F4-Discovery's LED
from ruby

78. generated mrbgem files
mrbgem wizard can create necessary files,
directory structure and template files

79. generated mrbgem template

80. add code for Led class
← class
← constants
↑ methods

81. build_config.rb for RasPi

82. libmruby.a generated

83. CREATE RasPi'S PROJECT
●
Create new C project
●
Create new files
–
demo.c
–
syscalls.c
–
vectors.s
–
memmap
–
makefile
–

84. create app project

85. Write ruby code
●
Insert “beginning tag” and “ending tag”
●
write ruby code between beginning tag and ending tag
●
Two ways to embed ruby code
1. se
U
menu bar
Insert ruby code in .c file
2. se
U
tool bar
/* <ruby->
...
<-ruby> */
Insert .rb file name in .c file
/* <rubyfile->
aaa.rb
<-rubyfile> */

86. before conversion

87. execute mrbc wrapper

88. after conversion

89. OpenOCD uses gdb and telnet
Eclipse
gdb
command Interface
telnet
port 3333
openocd
RasPi
port 4444

90. openocd as external tool

91. call openocd

92. OpenOCD log in Eclipse

93. connect OpenOCD via telnet

94. setting gdb command

95. Another Demo: blinking LED &
MEMS Accelerometer
using STM32F4d
Power ON
blinking
mode
Push Button
Push Button
tilt sensor
mode
switching 2 modes by pushing button

96. Tilt sensor in STM32F4d
●
using 3-axis MEMS accelerometer
in STM32F4 Discovery
only use 2 axis (X and Y)
– LED show which side is downward
–

97. Another Demo: blinking LED &
MEMS Accelerometer
using STM32F4d
Power ON
blinking
mode
Push Button
Push Button
tilt sensor
mode
switching 2 modes by pushing button

98. future issues
●
Ruby source level debugger
●
●
support bytecodes generated by mrbc
more mrbgem samples

99. Our Links
●
source code
●
●
Eclipse Plugin download site (for Eclipse)
–
●
http:/
/github.com/yamanekko/mruby/tree/rubyconf
http:/
/yamanekko.github.io/mruby-tools-EclipsePlugin
This slide
●
http:/
/slideshare.net/yamanekko/rubyconf2013

100. Useful mruby links
mruby repos: https:/
/github.com/mruby/mruby
mruby.sh: http:/
/blog.mruby.sh/
Introduction to Lightweight Ruby "mruby" (by Toshiba):
http:/
/www.tjsys.co.jp/page.jsp?id=3059
mruby code search: http:/
/mruby-code-search.ongaeshi.me/
ngx_mruby: http:/
/matsumoto-r.github.io/ngx_mruby/
webruby: https:/
/github.com/xxuejie/webruby
mobiruby: http:/
/mobiruby.org/

101. Thanks!
Happy mruby Hacking!
special thanks to: @tenderlove and @_zzak