Building Air Purifier and Pollution Sensors with the help of Ruby in Beijing. Talk was given at eurucamp 2014 in Berlin.

1. Internet
of
Dusty Things
by Daniel Bovensiepen

2. Building Metros
mruby core committer
<3 3D Printer

3. – Objective
“My kid is the youngest attendee @eurucamp 2014.
I want him to be the oldest @eurucamp 2114.”

4. Airpocalypse
~2

6. Masks
self-protection outside

8. Bad Air Good Air
MAGIC(TM)

9. Bad Air Good Air
MAGIC(TM)
airflow

10. 1. Version
• Dual-use of dorm room fan
• HEPA filter (80RMB)
• Tape and cardboard

12. ~7

13. –Dylos Serial reading
port = ARGV[0]
logfile = ARGV[1]
ser = SerialPort.new(port, 9600, 8, 1, SerialPort::NONE)
loop do
line = ''
loop do
char = ser.getc
# .. normalize line format ..
sleep 0.1
end
File.open(logfile, "a+") do |f|
txt = "#{DateTime.now.strftime("%Y-%m-%d--%H-%M-%S")} #{line.strip}"
f.puts txt
end
end

14. Dylos

15. Dylos

16. Dylos

17. expensive

18. –Cross Compile mruby configuration to ARM
http://blog.mruby.sh/201305310507.html

19. –SHINYEI TECHNOLOGY Co., Ltd.
“Thank you for your inquiry of Shinyei Particle Sensor.
We usually do not disclose the information you have inquired.”

20. expensive

21. –SAMYOUNG S&C Co., Ltd.

22. –SAMYOUNG S&C Co., Ltd.

24. –flank Algorithm
# .. mcu loop ..
if digitalRead(pin) == LOW
unless was_low?
# just changed to low; lets save the start
start_low = millis
was_low? = true
end
else
if was_low?
# Low pulse complete
# Calculate the duration of the low pulse
duration = millis - start_low
# Valid low pulses are only 10ms to 90ms long
low_sum += duration if duration >= 10 && duration <= 90
not_low_anymore
end
end

25. –flank Algorithm
# .. mcu loop ..
if digitalRead(pin) == LOW
unless was_low?
# just changed to low; lets save the start
start_low = millis
was_low? = true
end
else
if was_low?
# Low pulse complete
# Calculate the duration of the low pulse
duration = millis - start_low
# Valid low pulses are only 10ms to 90ms long
low_sum += duration if duration >= 10 && duration <= 90
not_low_anymore
end
end
Low Flank
High Flank

26. Dylos
DSM501a

27. Dylos
DSM501a

28. DIY Air Purifier
~17

30. airflow
airflow
airflow
under
pressure

32. Potsdam
Air
Good Air
airflow

33. Beijing
Air
Good Air
airflow

34. –PWM based on low pulse ratio
# .. mcu loop ..
# acquire ratio (usually between 0% to 10%)
ratio = lowpulseoccupancy_ratio(sensor_pin)
# map 0-10% to full PWM range and
# re-use this ratio as duty cycle
analogWrite(fan_pin, 255 / 100 * ratio * 10)

35. 2. Version
• using suction for air flow
• fan speed based on air quality

36. Internet of Dusty Things
• contains WIFI and ETH
• stable Linux support
• 4MB Flash
• 16MB RAM

37. mruby ARM
MIPS4k
Cross Compile

38. mruby ARM
MIPS4kmruby
Cross Compile
Cross Compile

39. http://blog.mruby.sh/201405051415.html
Port mruby to everything
mruby OpenWRT
MIPS4k
i.e. PS3Cross Compile
Cross Compile
pack

40. Feature Wish List
Cloud Storage of Pollution
Remote Control
Time Scheduler
Automatic Filter Exchange Notification
History Graph of Pollution
Software Upgrade

41. 3. Version
• remote control via wlan
• air sensing and filter check
• data graphing and collection

42. I see particles

43. Portable Counting

44. Sum-Up