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COPYRIGHT 2016 – Fundação CERTI
eLua _ Lua for
Microcontrollers
Vinicius Zein
Bruno Herrera

https://br.linkedin.com/in/viniciuszein
Vinicius Tadeu Zein

www.linkedin.com/in/bherrera
Bruno Herrera

R&D Institute
Founded in 1984 with the mission to
develop technology solutions for products
and processes
500 employees
Private, but results are reinvested in R&D
MCTI and SUFRAMA accredited – projects
with “Lei de Informática”, “Lei do Bem” and
Embrapii
More than 500 clients around the world

The information in this presentation was compiled from sources believed to be
reliable for informational purposes only.
Content includes opinions, presentations, articles, hyperlinks or other third
party content (“Third Party Material”) that is not intended to, nor constitutes an
endorsement by CERTI of the author or the Third Party Materials. The content
and views within the Third Party Material are solely those of the third party and
do not reﬂect the opinions of CERTI.
The opinions expressed in this presentation and on the following slides are
solely those of the
presenter and not necessarily those of CERTI. CERTI does not guarantee the
accuracy or
reliability of the information provided herein.
. Disclaimer

Ag
en
da
CAPÍTULO 1
Introdução
CAPÍTULO 2
Lógica de
negócios
CAPÍTULO 3
Embedded Lua
CAPÍTULO 4
DevKits e build
CAPÍTULO 5
eLua demo
CAPÍTULO 6
Wrap-up

INTRODUÇÃO
CAPÍTULO 1

CAPÍTULO 1 | INTRODUÇÃO
O que é Lua?

Onde está Lua?

LÓGICA DE
NEGÓCIOS
CAPÍTULO 2

CAPÍTULO 2 | LÓGICA DE NEGÓCIOS
Business Logic with script > Motivação
Processo de
Desenvolvimento
e.g. em C
1.  Alterar código
2.  Compilar
3.  Deploy

Business Logic with script > Processo de
desenvolvimento
com script
1.  Alterar código
2.  Compilar
3.  Deploy

Business Logic with script > Linguagens de script são
simples de se apreender
Menor complexidade
Precisa ser
integrável à
linguagem
compilada
(C, C++)

Business Logic with script Lua
Por que Lua?

Porque Lua
é leve x86 – 171K
arm – 160K
arm – 124K
liblua.so

Porque Lua é leve
180K
171K
160K
124K

Robusta &
estabelecida

Portátil &
livre

PODEROSA>permite orientação a objetos
>permite estender aplicações em outras
linguagens
>pode ser estendida por bibliotecas
escritas em outras linguagens
e também

Exemplo 1:
User interface do Set-Top Box CERTI

Integração Lua e C
CAPÍTULO 2 | INTEGRAÇÃO LUA E C

Módulo C

Lua
Bind

Módulo C

Bind

Módulo C

Bind

Módulo C

Bind

CAPÍTULO 3 | EMBEDDED LUA
2 ﬂavors:
> Aplicação C inicializa scripts Lua
> Script Lua carrega biblioteca naNva
É possível ter
a combinação
dos dois

Aplicação C inicializa máquina Lua
> lua_State *lua_newstate (lua_Alloc f,
void *ud);
> void luaL_openlibs (lua_State *L);
> int luaL_doﬁle (lua_State *L, const
char *ﬁlename);
> int lua_pcall (lua_State *L, int nargs,
int nresults, int msgh);
> void lua_close (lua_State *L);

Integração Lua e C > Inicialização da máquina Lua

Integração Lua e C > Bind para ser usado em Lua

IntegraçãoLuaeC

Integração Lua e C > Biblioteca C ( ? ) em Lua

CAPÍTULO 2 | EXEMPLOS
Exemplo 1:
Modiﬁcação do menu do STB Certi

Exemplo 2:
Modiﬁcação da interface do IP Phone


Embedded Lua
CAPÍTULO 3

“Microcontrollers are designed for
embedded applications, in contrast to
the microprocessors used in personal
computers or other general purpose
applications consisting of various
discrete chips.”
-Wikipedia

BSP(board support package) / HAL
(hardware abstraction layer) provided
by the “Chip” vendor
Hardware dependent code, not
portable
No operating system
Hard to port applications
Hard to update on the ﬁeld
Do not forget: it is all about
registers!!
without
addition; basic
and simple
Bare Metal

eLua www.eluaproject.net
Embedded power, driven by Lua
Quickly prototype and develop embedded
software applications with the power of Lua and
run them on a wide range of microcontroller
architectures
MicroPython micropython.org
MicroPython is a lean and eﬃcient
implementation of the Python 3 programming
language that includes a small subset of the
Python standard library and is optimised to run
on microcontrollers and in constrained
environments.
Netduino www.netduino.com
Netduino, an open-source electronics platform
using the .NET Micro Framework.
Cont: JavaME,
Not so bare
Bare Metal

e-Lua Embedded Lua
On a wide range of
microncontrollers
The power of Lua
Flexibility
Rapid prototyping
Reduced time-to-market

eLua is not an operational system
commercial software
nor GPL
reduced Lua
platform speciﬁc

Lightweight,
but...

Porting eLua > prerequisites
Program memory
128kB (basic image)
256kB (full image)
RAM
minimum 32kB*
Recommended 64kB
* LTR (Lua Tiny RAM) – less than 32kB

eLuaArchitecture

adc
elua
bit
i2c
can
net
cpu
pack
pd
spi
pio
term
pwm
tmr
rpc
uart
eLuaGenericmodules

eLuaPlatformmodules
mbed.pio
lm3.disp
str9.pio
mizar32.lcd
Mizar32.rtc

DevKits e Build
CAPÍTULO 4

CAPÍTULO 4 | DEVKITS AND BUILD
eLuaSupportedtargets

src/platform/<name>
> type.h – specific data types
> conf.lua – build configuration file
> stacks.h – stack size definition
> platform.c – platform interface impl
> platform_conf.h – info about platform
and build config
> others: network config, start up,
linker, CPU support package
Porting eLua > structure
CAPÍTULO 4 | DEVKITS AND BUILD

>type.h–speciﬁcdatatypes
Porting eLua >
structure

>conf.lua–buildconﬁgurationﬁle
Porting eLua >
structure

Porting eLua >
structure
>stacks.h–stacksizedeﬁnition

>platform.c–platforminterfaceimpl

>stm32f4xx_conf.h–infoabout
platformandbuildconﬁg

Porting eLua > new CPU
1.  edit build_data.lua
2.  add a new board to eLua
3.  customize the list of source ﬁle and/or
compilation ﬂags

Porting eLua > new board
1.  Name your board - stm32f429disco
2.  Write a configuration file
3.  Change the file list according to the board name
> cp boards/known/stm32-port407z.lua boards/
known/stm32f429disco.lua
> edit stm32f429disco.lua to set up UART and RX/
TX pins

eLua demo
CAPÍTULO 6

CAPÍTULO 6 | eLUA DEMO
Target
Action

Tools
Toolchain
https://launchpad.net/gcc-arm-
embedded/4.9/4.9-2014-q4-major
sudo add-apt-repository ppa:terry.guo/gcc-
arm-embedded
sudo apt-get update
sudo apt-get install gcc-arm-none-eabi
Open OCD
git clone git://git.code.sf.net/p/openocd/
code openocd
cd openocd
git submodule init && git submodule update
&& ./bootstrap && ./conﬁgure --enable-
stlink && make && sudo make install
Action

GPIO
The famous hello world “led blink” at
user space
gpio = (bank * 16) + pin
gpio = 6 * 16 + 14(LD4) = 110
cd /sys/class/gpio
echo 110 > export
echo out > gpio110/direction
Action

Wrap-up
CAPÍTULO 6

CAPÍTULO 6 | WRAP-UP

Take away
Use a script language for
app development
Lua is lightweight,
portable and easy to use
eLua runs in
microcontrollers
CAPÍTULO 6 | WRAP-UP

?

Obrigado!
https://br.linkedin.com/in/viniciuszein
https://www.linkedin.com/in/bherrera

Links úteis
www.lua.org
site principal para todas as coisas Lua
www.eluaproject.net
site do projeto eLua

Referências
Slide 6 h)p://www.lua.org/
Slide 33, 35 e 36 h)p://www.eluaproject.net

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