I'm an avid home brewer and what better than to combine your hobbies in the service of home brewing? The Raspberry Pi is a low cost computer with some very nifty interfaces for interacting with the real world. We can utilize that to monitor all things home brewing to make sure our brews come out great! Join me for a whirlwind tour of brewing beer and hacking Erlang on the Raspberry Pi. Agenda: The Raspberry Pi Erlang on Pi using Erlang/ALE (Actor Library for Embedded) Beer Brewing Monitoring temperatures Target audience: Anyone interested in Raspberry Pi and how you can get started with Erlang on it. Anyone interested in beer and how it's made.

1. Brewing ALE with Pi
Kristian Kristensen
@kkristensen

2. Get $5 to start:!
http://bit.ly/
VenmoKristian

3. Agenda
•
Beer Brewing
•
Raspberry Pi
•
Erlang/ALE
•
Monitoring temperatures

23. Raspberry Pi
•
ARM 700 MHz CPU
•
512 MB RAM
•
10/100 Ethernet
•
HDMI, Comp. Video, Audio.
•
$40!

24. Interface Real World (I)
•
GPIO
•
I2C
•
SPI
•
<Others>

25. Interface Real World (II)
•
Memory Mapped
•
/dev/mem
•
•
Kernel modules
•
•
Fast, needs root, dangerous!
Slow, doesn’t need root, easier, safer
Can Erlang help us?

26. Erlang/ALE
•
Actor
•
Library for
•
Embedded
https://github.com/esl/erlang_ale

27. Erlang (hearts) Embedded
•
Soft real time
•
Concurrency and Parallelism
•
Fault tolerant & Robust
•
Hot-code loading
•
(http://www.erlang-embedded.com/2013/10/minimal-downtime-in-flight-drone-firmware-upgrade-in-erlang/)

28. Architecture
•
Fix the mess
we saw earlier
•
Familiar
abstractions
•
Clean model

29. What works
•
GPIO and GPIO interrupts
•
Basic I2C and SPI
•
Erlang Solutions actively working on it

30. GPIO
A
{init, 17, output}
GPIO
pin 17

31. GPIO
A
B
{state, 17, high}
GPIO
{state, 17, low}
pin 17
{state, 17, high}
C

32. GPIO Supervisor
•
Replaces locks
•
•
Access Control, Mutual Exclusion
Safety constraints
•
Toggling, sequence detection, direction
control, etc.

33. Blink some LEDs
{ok, _} = gpio:start_link(?LED_PIN, output),
!
blink() ->
gpio:write(?LED_PIN, 1),
!
timer:sleep(1000),
!
gpio:write(?LED_PIN, 0),
!
timer:sleep(1000).

34. Blink some LEDs
•
http://bit.ly/18KP8xF

35. Interrupts
{ok, _} = gpio:start_link(?IN_PIN, input),
!
ok
= gpio:set_int(?IN_PIN, rising),
!
handle_info({gpio_interrupt, _Pin,
_Condition}, State) ->
blink().

37. 1-wire
•
Creates a network of sensors all communicating
using 1 single wire
•
Great digital thermometer sensor available
•
DS18B20

40. Raspberry Pi & 1-wire
•
Kernel module
•
•
/sys/bus/w1/devices/28-0000044719d7/w1slave
=>
•
4b 01 4b 46 7f ff 0e 10 d8 : crc=d8 YES
4b 01 4b 46 7f ff 0e 10 d8 t=26125

41. Read temperature
•
read(<<A1:16,_,A2:16,_,A3:16,_,A4:16
,_,A5:16,_,A6:16,_,A7:16,_,A8:16,_,C
RC:16,_,$:,_,”crc=",CRC:
16,_,"YES",Rest0/binary>>
•
read(<<A1:16,_,A2:16,_,A3:16,_,A4:16
,_,A5:16,_,A6:16,_,A7:16,_,A8:16,_,C
RC:16," t=",Rest/binary>>
•
http://bit.ly/1cst0ah

44. Projects
•
Kegerator control
•
Boil Wort
•
Strike water, Hot Liquor Tank
•
Mash temperature
•
Fermentation Chamber
Control

45. Thank you

46. Links
•
https://github.com/esl/erlang_ale
•
http://www.erlang-embedded.com/
•
Blink LEDs: http://bit.ly/18KP8xF
•
Read Temperature: http://bit.ly/1cst0ah