Just a quick example of using a gameboy printer with pokitto…
https://os.mbed.com/users/spinal/code/GB_Printer/
You’ll have to cut up a gameboy link cable to do this one.
Pins used are set in the main.c file
DigitalInOut datClk(P0_11);
DigitalInOut datIn(P0_17);
DigitalInOut datOut(P0_13);
// GND also
You can probably use any pins you like, I chose these because they are next to each other.
Yeaahh, you finaly have it working ? How did you solve it ? 
Would you believe most of my issues were low battery related?
lol really, that was it? I geuss you dont have the original power supply for the printer then ? Or is it powered by the GB ?
It’s supposed to be powered by batteries (6xAA). But I modified mine to use a 9v power supply.
Neat.
I wonder if my local computer museum has a GB Printer.
Is the next step to try and connect the gameboy camera to the pokitto?
The GB Camera is a game cart you have to emulate the Gameboy to let it capture
If you want a camera you can look into Arduino camera modules
I have too much camera gear as it is. I was more wondering how inspired you were on this theme and whether it was a actually possible to wire something into the PEX that could connect a GB game cart.
you can, its usualy just 2 chips rom and lockoutchip (on a regular game), but doing something with the data is another thing
Good News!!!
Look my face, it comes to my GB photo.
My friend just give me a GB printer from Japan. But I don’t have papers using it.
Maybe I can buy some commeral paper and cut it suitable size.
You can buy the correct size from eBay etc. However I just asked at a local store for some left over receipt paper, as there is usually a little left on the roll, then I just cut it to size.
OK, had a go a converting this to uPython…
# Welcome to Python on Pokitto!
from umachine import *
import upygame as upg
import umachine as pok
upg.display.set_palette_16bit([
63519,57545,60340,31666,
04266,48664,19770,01065,
24009,63301,23209,62723,
63060,65404,41606,00000,
])
# Set the pins, I chose these because they were next to each other
datClk = Pin( Pin.EXT1, Pin.OUT );
datOut = Pin( Pin.EXT3, Pin.OUT );
datIn = Pin( Pin.EXT5, Pin.IN ); # needs to be pullup
# Global variables
checksum = 0;
respond = [0 for x in range(2)]
#Receive data from the printer
def getResponse():
respond[0] = 0;
respond[1] = 0;
# read 2 bytes
for numBytes in range(2):
# 8 bits per byte
for numBits in range(8):
respond[numBytes] <<=1; # shift the data left
datClk = 0;
wait(55);
if( datIn ):
respond[numBytes] |= 1;
wait(55);
wait(200);
wait(500);
#Send a byte to the printer
def sendByte( byteToSend ):
global checksum
# Update checksum
checksum += byteToSend;
# Loop through the 8 bits in the byte
for t in range(8):
datOut = byteToSend & 128;
datCLk = 0;
wait(55);
datClk = 1;
byteToSend <<=1;
wait(55);
datOut = 0;
wait(300);
def sendChecksum():
# grab the checksum value
lineChecksum = checksum;
# Send low Byte of checksum
sendByte(lineChecksum & 0xFF);
# Send high Byte of checksum
sendByte(lineChecksum >> 8);
def sendHeader():
# Send magic header
sendByte(0x88);
sendByte(0x33);
# reset checksum value
checksum = 0;
def initPrinter():
# Send the header bytes
sendHeader();
sendByte(0x01); # 0x01 = init printer
sendByte(0x00); # 0x00 = No compression, 0x01 = run-length compression
sendByte(0x00); # 16bit number = length of data being sent
sendByte(0x00); #
sendChecksum(); # send checksum for verification
def printLine():
sendHeader();
sendByte(0x04); # 0x04 = Data to print
sendByte(0x00); # 0x00 = No compression, 0x01 = run-length compression
sendByte(0x80); # 16bit number = length of data being sent
sendByte(0x02); # in this case 0x0280 = 640 bytes, the maximum.
# send the print data
for t in range(640):
sendByte(0xFF);
sendChecksum();
getResponse(); # We don't need to check the response, just allow it to be sent
sendHeader();
sendByte(0x04); # 0x04 = Data to print
sendByte(0x00); # 0x00 = No compression, 0x01 = run-length compression
sendByte(0x00); # 16bit number = length of data being sent
sendByte(0x00); # in this case 0 for no data.
sendChecksum();
getResponse(); # We don't need to check the response, just allow it to be sent
sendHeader();
sendByte(0x02); # 0x02 = Print current buffer
sendByte(0x00); #
sendByte(0x04); # 0x04 = Lenth of data being sent
sendByte(0x00); #
sendByte(0x01); # 0x01 = Print, 0x00 = line feed
sendByte(0x00); # amount of margin to leave
sendByte(0xE4); # Palette data 0xE4 = 11 10 01 00 black grey1 grey2 white
sendByte(0x40); # 0x40 Can't remember what this was :-(
sendChecksum();
getResponse(); # We don't need to check the response, just allow it to be sent
# Main
datClk = 1; # Start with clock high
datOut = 0; # Data low
pok.draw_text(0,0,"Init Printer", 1)
upg.display.flip();
initPrinter();
if( respond[0]==0x81 and respond[1]==0x00 ):
pok.draw_text(0,8,"Printer responded!", 1)
upg.display.flip();
t=0;
# print 9 lines of data
while(t <9):
sendHeader();
sendByte(0x0F); #
sendByte(0x00); #
sendByte(0x00); #
sendChecksum();
getResponse(); # We don't need to check the response, just allow it to be sent
if(respond[1]&0x0B):
printLine();
t=t+1;
Doesn’t seem to work. Using my analyser, all 3 pins are brought low and nothing else happens. Anyone know why? I would expect at least the clock pin should flip 
Instead of datClk = 1 try datClk.on() (and datClk.off() )
For an analog out pin you have to define it like this:
datOut = Pin ( Pin.EXT1, Pin.ANALOG_OUT )
I have never tested analog output with MP 
Edit: Unfortunately it looks like ANALOG_OUT is not implemented
Switched to digital pins and changed to the above activation and the pins now change state!
Now to get it communicating with the printer…
[edit] The printer communicated back by pulling the pin low… easy when internal pullups are supported 
hmmm, looks like wait(55//1000); doesn’t work to get a 55 millisecond delay
Does uPython support millisecond delays?
Wait takes the value as milliseconds. So wait(1000) waits 1 second.
oops, mistyped… mean microseconds
something like wait_us(55); so what I’m looking for
No, waiting for microseconds is not supported.