The Emotional Stock Market

Documentation for Printing TweetsBy Max Dovey

Receipt printers

All shares in an emotional enterprise are sold by printing tweets as receipts to the customer. I have to work out how to print tweet search results.

I need to get 3 cheap thermal receipt printers.

Checklist

An old receipt printer - I have a Citizen CBM-231

from ebay

An Arduino board, bread board and jump wires (from Cool

Components)

An Arduino Ethernet shield (also from Cool Components)

A MAX233 Chip and serial plug (from Maplins)

The serial output of the Arduino board isn't natively

compatible with the printer - you need to run the signal

through the MAX233 chip to transform the output to the

correct voltage.

http://tomtaylor.co.uk/projects/microprinter

Luckily I wasn’t the first person to want to do this….

Product IdentifiersBrand CitizenModel CBM-1000MPN CBM1000IIUF120S-CW, cbm1000iiuf120cw

Key FeaturesPrinter Type LabelFamily Line Citizen CBMOutput Type Monochrome PrinterBlack print speed up to 150 mm/secPlatform PC

Technical FeaturesExtend Printer Technology Thermal InkjetInterface Cable, Parallel (IEEE1284), RJ-45 Network Adapter, Serial

RS-232C, USBForm Factor Desktop, Point Of Sale

Media

Media Type Roll PaperMax Media Size Roll (8 cm)Media Capacity 1 Roll(s)

NetworkingNetworking Type 10/100BaseTData Link Protocol Ethernet, Fast Ethernet, IEEE 1284 ECP/EPP

I have bought 8 CBM 1000 printers.

Guide to getting the CBM1000 up and running.

http://microprinter.pbworks.com/w/page/21489360/CBM-1000

Once my eight receipt printers arrived I checked they all turned on. 5 out of the 8 worked on there test print function.

Getting the printer printing digital text

The Input on the printer is a serial female 25pin. The computer signal has to be changed to talk to this analogue input. So a bit of electrics and circuits has to happen. Luckily I found this circuit diagram for my cbm1000. ( a neater version of what is above)

The Max232 chip converts the voltage from the computer to the printer. I learnt a lot about jump cables, capacitors and fiddled for a great deal of time. Once the circuit was made we had to test it. We found some code by roo Reynolds on github – https://github.com/rooreynolds/microprinter/that is a driver for processing to send digital signals to receipt printer via arduino.

TEST PRINT WORKED

With Roo Reynolds arduino sketch we were able to enter text to print in processing via arduino then converted into a 25 pin serial signal.

PROBLEMS The arduino circuit was very messy and I was concerned that it would be vulnerable during the installation.

I did not know how to get the printer to print tweets from twitter in real time.

Python

According to other examples of other social microprinting devices it was easier to send online posts to a receipt printer with the programming language Python. Ben O’ Steen had created a sketch using roo Reynolds code for processing to print onto receipts. https://github.com/benosteen/microprinter

The Python option was more appealing because it cut out all the wires, at the expense of having to work in a much more complex programming language. I also found a very simple example from a german hackerhouse that appeared to be so simple –

import serial import time import tweepy # Twitter credentials auth = tweepy.OAuthHandler("<InsertConsumerKeyHere>", "<InsertConsumerSecretHere>") auth.set_access_token("<InsertAccessTokenHere>", "<InsertAccessTokenSecretHere>") api = tweepy.API(auth) # receipt printer is connected via serial-to-usb converter printer = serial.Serial("/dev/ttyUSB0", 19200) while True: # read savepoint file = open("id", "r") savepoint = file.read()

file.close() timeline = api.friends_timeline() timeline.reverse() for status in timeline: # assuming that Twitter assigns IDs in ascending order

message = "(%(created)s) %(screenname)s: %(statusmessage)s\n\n" % \ {"created" : status.created_at,

"screenname" : status.user.screen_name, "statusmessage" : status.text.encode('cp437', 'replace')}

printer.write(message) # write savepoint file = open("id", "w")

file.write(str(status.id)) file.close() # Twitter API allows 350 requests per hour (every ~11 sec

should be ok ;) time.sleep(11)

http://hickerspace.org/wiki/Microprinting

This code pulled tweets every 11 seconds and printed them on a receipt printer. It all seemed to be very efficient. However I did not have the programming knowledge to get python working. I began requesting assistance.

Advice from geniuses Efficiency isnt really necessary - just a method that you can get to work ;)

If you are more familair with python then go with that.

Nick- Show quoted text –

- be wary of the 9 pin to 25 pin - it might be fine but of the wrongvariety in which case no serial gets through to your printer and youdon't know which part is faulty.

have you done a Power On Self Test on the printer? normally you holddown LF, switch on the power and it'll print out a self test (so youcan confirm that the print head etc is working).

re. python code my github project should point you in the right direction:https://github.com/ianozsvald/SocialMicroprinter

i'd say (in order of importance):* confirm that the printer does a self test and prints ok (without aserial lead)* confirm that you can use a serial program (e.g. HyperTerm, CoolTerm)to talk to the printer* test that pySerial (or serial driver for whatever language you wantto use) works* add twitter on top

don't jump the stages else you won't know which parts of the puzzleare dead. getting the right serial lead combo (and serial settingse.g. 9600 8N1, 19200 8N1 etc) is key to the whole puzzle.

re. buildbrighton - i'm the only python programmer and i hardly attend(and for the next month there's no way - i'm under several bigdeadlines with conference talks/tutorials to write! mongo busy!). i'd

really suggest the London Hackerspace, they're lovely and will behappy to offer some guidance if you just rock up and ask

I also visited the London Hackerspace on Tuesday 17th MayThe London Hackspace is a non-profit, community-run hacker space in central London. We provide infrastructure for our members to make and learn things.london.hackspace.org.uk/

It was a really great communal space with some great people, sharing great ideas and awesome tools. However this was there open evening and it felt more for socialising then coding. I returned still non the wiser. I decided to go back to using processing, the language I was a bit more experienced in.

Gregzek, the Wimbledon college technician helped me to connect a processing sketch that pulled tweets to arduino. By sending it down the serial monitor. This was successful and we had our first tweet printed on receipt. IT was based on sketches that I had found whilst researching twitter based processing environments.

ConclusionGetting the receipt printers working caused the most concern during the creative process. I have learnt not to try and connect ancient analogue technology. However it has also been the most rewarding outcome and will be the core aspect of the emotional stock market.

Many Thanks to Archie Sinclair, Gregzek, Tinker Nick, Ian Oszvald, Ben o Steen and the London Hackerpsace for helping me all out to an incredible degree.

Receipt printer bibliography

Arduino forum http://www.arduino.cc/

http://arduino.cc/blog/category/hacks/urban-hacks/page/2/ (the twitter typewriter)

http://www.flipbit.co.uk/micro-printer.html (rss microprinter)

Models – CBM-231 (used by Tom) CBM233http://little-scale.blogspot.com/2007/11/arduino-printer-how.html

The core arduino sketch by Roo-http://rooreynolds.com/2009/02/01/microprinter/

guide by the excellent Ian Oszvaldhttp://ianozsvald.com/2010/11/06/building-a-social-microprinter/

Another online guide –http://adamendicott.com/blog/2009/mar/22/my-microprinter/

The Wikihow page http://microprinter.pbworks.com/w/page/20867146/FrontPage

The German python code http://hickerspace.org/wiki/Microprinting