This project shows how to recycle an old keyboard and a dot matrix printer to make a typewriter.

What and how.

The idea is connect the keyboard to the printer with a basic and cheap interface, i have used Arduino because is a fast development board for this kind of  projects and have a large community behind. The board read the keyboard signals (use a data/clock system) and transform this info about the character to the printer. Parallel format controlling the strobe.


Is very basic too, a keyboard adapter with clock, data, power and GND (figure-1), a printer adapter with 8 data bits, strobe and GND (figure-2) all this

Connected to Arduino as figure-3.


The source code.

// Typewriter with an old AT Keyboard and a Dot Matrix printer.
// 2011 www.xbot.es
// Francisco Reinoso "furri"

#include <PS2Keyboard.h> // library to use a PS2Keyboard with Arduino
#include <string.h>
#include <stdio.h>

#define KBD_CLK_PIN 3
#define KBD_DATA_PIN 2
#define d0 4
#define d1 5
#define d2 6
#define d3 7
#define d4 8
#define d5 9
#define d6 10
#define d7 11
#define strobe 12
#define autofd 13

PS2Keyboard keyboard;

int caracter = 0;

void setup() {
pinMode(d0, OUTPUT);
pinMode(d1, OUTPUT);
pinMode(d2, OUTPUT);
pinMode(d3, OUTPUT);
pinMode(d4, OUTPUT);
pinMode(d5, OUTPUT);
pinMode(d6, OUTPUT);
pinMode(d7, OUTPUT);
pinMode(strobe, OUTPUT);
pinMode(autofd, OUTPUT);

#define is_printable(c) (!(c&0x80)) // don't print if top bit is set

void imprime(int letra)
// decode character into 8 bits
if (letra >= 128) { letra = letra - 128; digitalWrite(d0,HIGH); } else { digitalWrite(d0,LOW); }
if (letra >= 64) { letra = letra - 64; digitalWrite(d1,HIGH); } else { digitalWrite(d1,LOW); }
if (letra >= 32) { letra = letra - 32; digitalWrite(d2,HIGH); } else { digitalWrite(d2,LOW); }
if (letra >= 16) { letra = letra - 16; digitalWrite(d3,HIGH); } else { digitalWrite(d3,LOW); }
if (letra >= 8) { letra = letra - 8; digitalWrite(d4,HIGH); } else { digitalWrite(d4,LOW); }
if (letra >= 4) { letra = letra - 4; digitalWrite(d5,HIGH); } else { digitalWrite(d5,LOW); }
if (letra >= 2) { letra = letra - 2; digitalWrite(d6,HIGH); } else { digitalWrite(d6,LOW); }
if (letra >= 1) { digitalWrite(d7,HIGH); } else { digitalWrite(d7,LOW); }
// send the character to the printer

void loop() {
if(keyboard.available()) {
byte c = keyboard.read();
if ( c == 13 ) { Serial.print(c); imprime(10); }
if ( is_printable(c) ) { Serial.print(c); imprime(c); } // don't print special characters

<p>this kind of printer works? </p><p>http://www.banggood.com/POS-5890K-58mm-Thermal-Receipt-Printer-Support-WIndows-Linux-p-1053549.html?rmmds=search</p>
<p>I made this for standard LPT printers (Centronics cable), your printer seems USB interfaced... </p>
<p>hello! this is really a great project!!<br>I was wondering if it is possible to control, for example, the space between the letters, or something like that - by messing with the code, or actually put that function in one key of the keyboard.<br>Also, this code can be used for a bigger dot matrix printer? A4, A3 paper size?<br><br>Thank you!</p>
Yes, you can write in a A4 printer, in a laser one also, you can change letter types, bold... and more...<br> <br> BUT... those things depends on the printer that you are using, you must know the Escape Codes (named Printer Codes too), something like this<br> <br> http://www.bighole.nl/pub/mirror/homepage.ntlworld.com/kryten_droid/Atari/ST/spg/st_prog_guide_c.htm<br> <br> I use those codes last time 15 years ago so actual printers don't use i think and to find information about this will be harder and harder, but in searching and discovering is the enjoy.<br> <br> good luck in your project.
<p>Great Build!</p>
Been trying this all day and have had no luck. Hopefully you can offer some guidance. <br> <br>First off, do you tie all the grounds to ground, or just strobe and d0-d7? <br>http://www.hilmanind.com/pinouts/cent36.htm - looks like there are 15 total grounds. <br> <br>What about auto-feed, what are you doing with it? <br> <br>What did you do with all the wires you didn't need? just leave the dangling? <br> <br>Thanks!
i want a dot matrix printer <br>do you think that you could invent a code that writes without the keyboard <br>you rock
print without keyboard, easy... What do you want to print?<br><br>&quot;I'm the gosth of the printer... HaHaHA&quot;<br><br>a good joke.
what kind of arduino do I need?<br>is it works whit uno?
any arduino works
i love it <br>

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More by furri:Flying Witch Laser Transceiver (laser data link) Making a typewriter with an old keyboard and a dot matrix printer 
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