Simple project to print text to Epson receipt.

receipt.py

# Print text to serial Epson printer. Escape codes are Epson ESC/POS.
#
#     pip install pyserial jeni # Developed on Python 3.4.

import struct

import serial
from jeni import annotate, partial
from jeni import Injector


PORT = '/dev/ttyS0'
BAUDRATE = 19200
XONXOFF = True
LINEWIDTH = 42
ENCODING = 'ascii'
LINESCUT = 8


@annotate
def reset(ser: 'serial'):
    return ser.write(b'\x1d@')


@annotate
def feed(linecount, ser: 'serial'):
    return ser.write(b'\x1bd' + struct.pack('B', linecount))


@annotate
def cut(ser: 'serial'):
    return ser.write(b'\x1dV\x00')


@annotate
def writetext(
        text,
        ser: 'serial',
        reset: partial(reset),
        feed: partial(feed),
        cut: partial(cut),
        encoding=ENCODING,
        linescut=LINESCUT):
    reset()
    ser.write(text.encode(encoding))
    feed(linescut)
    cut()


def count_lines(text, width=LINEWIDTH):
    return sum(_count_lines(text, width=width))


def _count_lines(text, width):
    for line in text.splitlines():
        if not line:
            yield 1
        else:
            div, mod = divmod(len(line), width)
            if div:
                yield div
            if mod:
                yield 1


@Injector.factory('serial')
def serial_factory():
    return serial.Serial(port=PORT, baudrate=BAUDRATE, xonxoff=XONXOFF)


if __name__ == '__main__':
    import sys

    injector = Injector()
    injector.apply(writetext, sys.stdin.read())