Cat thermal printer

CircuitPython_BLEThermalPrinter/code.py

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+import os
+
+import board
+import keypad
+import ulab.numpy as np
+
+from adafruit_ble import BLERadio
+from adafruit_ble.advertising import Advertisement
+
+from thermalprinter import CatPrinter
+from seekablebitmap import imageopen
+
+ble = BLERadio()  # pylint: disable=no-member
+
+buttons = keypad.Keys([board.BUTTON_A, board.BUTTON_B], value_when_pressed=False)
+
+def wait_for_press(kbd):
+    """
+    Wait for a keypress and return the event
+    """
+    while True:
+        event = kbd.events.get()
+        if event and event.pressed:
+            return event
+
+
+def show(s):
+    """
+    Display a message on the screen
+    """
+    board.DISPLAY.auto_refresh = False
+    print("\n" * 24)
+    print(s)
+    board.DISPLAY.auto_refresh = True
+
+
+def show_error(s):
+    """
+    Display a message on the screen and wait for a button press
+    """
+    show(s + "\nPress a button to continue")
+    wait_for_press(buttons)
+
+
+def find_cat_printer(radio):
+    """
+    Connect to the cat printer device using BLE
+    """
+    while True:
+        show("Scanning for GB02 device...")
+        for adv in radio.start_scan(Advertisement):
+            complete_name = getattr(adv, "complete_name")
+            if complete_name is not None:
+                print(f"Saw {complete_name}")
+            if complete_name == "GB02":
+                radio.stop_scan()
+                return radio.connect(adv, timeout=10)[CatPrinter]
+
+
+image_files = [
+    i
+    for i in os.listdir("/")
+    if i.lower().endswith(".pbm") or i.lower().endswith(".bmp")
+]
+image_files.sort(key=lambda filename: filename.lower())
+
+
+def select_image():
+    i = 0
+    while True:
+        show(
+            f"Select image file\nA: next image\nB: print this image\n\n{image_files[i]}"
+        )
+        event = wait_for_press(buttons)
+        if event.key_number == 0:  # button "A"
+            i = (i + 1) % len(image_files)
+        if event.key_number == 1:  # button "B"
+            return image_files[i]
+
+
+printer = find_cat_printer(ble)
+
+def main():
+    try:
+        filename = select_image()
+
+        show(f"Loading {filename}")
+
+        image = imageopen(filename)
+        if image.width != 384:
+            raise ValueError("Invalid image.  Must be 384 pixels wide")
+        if image.bits_per_pixel != 1:
+            raise ValueError("Invalid image.  Must be 1 bit per pixel (black & white)")
+
+        invert_image = image.palette and image.palette[0] == 0
+
+        show(f"Printing {filename}")
+
+        for i in range(image.height):
+            row_data = image.get_row(i)
+            if invert_image:
+                row_data = ~np.frombuffer(row_data, dtype=np.uint8)
+            printer.print_bitmap_row(row_data)
+
+        # Print blank lines until the paper can be torn off
+        for i in range(80):
+            printer.print_bitmap_row(b"\0" * 48)
+
+    except Exception as e: # pylint: disable=broad-except
+        show_error(str(e))
+        image_files.remove(filename)
+
+while True:
+    main()

CircuitPython_BLEThermalPrinter/seekablebitmap.py

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+import struct
+
+class SeekableBitmap:
+    """Allow random access to an uncompressed bitmap file on disk"""
+    def __init__(
+        self,
+        image_file,
+        width,
+        height,
+        bits_per_pixel,
+        *,
+        bytes_per_row=None,
+        data_start=None,
+        stride=None,
+        palette=None,
+    ):
+        """Construct a SeekableBitmap"""
+        self.image_file = image_file
+        self.width = width
+        self.height = height
+        self.bits_per_pixel = bits_per_pixel
+        self.bytes_per_row = (
+            bytes_per_row if bytes_per_row else (bits_per_pixel * width + 7) // 8
+        )
+        self.stride = stride if stride else self.bytes_per_row
+        self.palette = palette
+        self.data_start = data_start if data_start else image_file.tell()
+
+    def get_row(self, row):
+        self.image_file.seek(self.data_start + row * self.stride)
+        return self.image_file.read(self.bytes_per_row)
+
+
+def _pnmopen(filename):
+    """
+    Scan for netpbm format info, skip over comments, and read header data.
+
+    Return the format, header, and the opened file positioned at the start of
+    the bitmap data.
+    """
+    # pylint: disable=too-many-branches
+    image_file = open(filename, "rb")
+    magic_number = image_file.read(2)
+    image_file.seek(2)
+    pnm_header = []
+    next_value = bytearray()
+    while True:
+        # We have all we need at length 3 for formats P2, P3, P5, P6
+        if len(pnm_header) == 3:
+            return image_file, magic_number, pnm_header
+
+        if len(pnm_header) == 2 and magic_number in [b"P1", b"P4"]:
+            return image_file, magic_number, pnm_header
+
+        next_byte = image_file.read(1)
+        if next_byte == b"":
+            raise RuntimeError("Unsupported image format {}".format(magic_number))
+        if next_byte == b"#":  # comment found, seek until a newline or EOF is found
+            while image_file.read(1) not in [b"", b"\n"]:  # EOF or NL
+                pass
+        elif not next_byte.isdigit():  # boundary found in header data
+            if next_value:
+                # pull values until space is found
+                pnm_header.append(int("".join(["%c" % char for char in next_value])))
+                next_value = bytearray()  # reset the byte array
+        else:
+            next_value += next_byte  # push the digit into the byte array
+
+
+def pnmopen(filename):
+    """
+    Interpret netpbm format info and construct a SeekableBitmap
+    """
+    image_file, magic_number, pnm_header = _pnmopen(filename)
+    if magic_number == b"P4":
+        return SeekableBitmap(
+            image_file,
+            pnm_header[0],
+            pnm_header[1],
+            1,
+            palette=b"\xff\xff\xff\x00\x00\x00\x00\x00",
+        )
+    if magic_number == b"P5":
+        return SeekableBitmap(
+            image_file, pnm_header[0], pnm_header[1], pnm_header[2].bit_length()
+        )
+    if magic_number == b"P6":
+        return SeekableBitmap(
+            image_file, pnm_header[0], pnm_header[1], 3 * pnm_header[2].bit_length()
+        )
+    raise ValueError(f"Unknown or unsupported magic number {magic_number}")
+
+
+def bmpopen(filename):
+    """
+    Interpret bmp format info and construct a SeekableBitmap
+    """
+    image_file = open(filename, "rb")
+
+    header = image_file.read(34)
+
+    data_start, header_size, width, height, _, bits_per_pixel, _ = struct.unpack(
+        "<10x4l2hl", header
+    )
+
+    bits_per_pixel = bits_per_pixel if bits_per_pixel != 0 else 1
+
+    palette_start = header_size + 14
+    image_file.seek(palette_start)
+    palette = image_file.read(4 << bits_per_pixel)
+
+    stride = (bits_per_pixel * width + 31) // 32 * 4
+    if height < 0:
+        height = -height
+    else:
+        data_start = data_start + stride * (height - 1)
+        stride = -stride
+
+    return SeekableBitmap(
+        image_file,
+        width,
+        height,
+        bits_per_pixel,
+        data_start=data_start,
+        stride=stride,
+        palette=palette,
+    )
+
+
+def imageopen(filename):
+    """
+    Open a bmp or pnm file as a seekable bitmap
+    """
+    if filename.lower().endswith(".bmp"):
+        return bmpopen(filename)
+    return pnmopen(filename)

CircuitPython_BLEThermalPrinter/thermalprinter.py

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+# Protocol information from Thermal_Printer Arduino library
+# https://github.com/bitbank2/Thermal_Printer/
+from adafruit_ble.uuid import StandardUUID
+from adafruit_ble.services import Service
+from adafruit_ble.characteristics.stream import StreamIn
+
+# Switch the printing mode to bitmap
+printimage = b"Qx\xbe\x00\x01\x00\x00\x00\xff"
+# Switch the printing mode to text
+printtext = b"Qx\xbe\x00\x01\x00\x01\x07\xff"
+# Command to feed paper
+paperfeed = b"Qx\xa1\x00\x02\x00\x1eZ\xff\xff"
+
+# this table helps compute the checksum of transmitted data
+# it is crc-8-ccitt
+checksumtable = (
+    b"\x00\x07\x0e\t\x1c\x1b\x12\x158?61$#*-"
+    b"pw~ylkbeHOFATSZ]"
+    b"\xe0\xe7\xee\xe9\xfc\xfb\xf2\xf5\xd8\xdf\xd6\xd1\xc4\xc3\xca\xcd"
+    b"\x90\x97\x9e\x99\x8c\x8b\x82\x85\xa8\xaf\xa6\xa1\xb4\xb3\xba\xbd"
+    b"\xc7\xc0\xc9\xce\xdb\xdc\xd5\xd2\xff\xf8\xf1\xf6\xe3\xe4\xed\xea"
+    b"\xb7\xb0\xb9\xbe\xab\xac\xa5\xa2\x8f\x88\x81\x86\x93\x94\x9d\x9a"
+    b"' ).;<52\x1f\x18\x11\x16\x03\x04\r\n"
+    b"WPY^KLEBohafst}z"
+    b"\x89\x8e\x87\x80\x95\x92\x9b\x9c\xb1\xb6\xbf\xb8\xad\xaa\xa3\xa4"
+    b"\xf9\xfe\xf7\xf0\xe5\xe2\xeb\xec\xc1\xc6\xcf\xc8\xdd\xda\xd3\xd4"
+    b"ing`ur{|QV_XMJCD"
+    b"\x19\x1e\x17\x10\x05\x02\x0b\x0c!&/(=:34"
+    b"NI@GRU\\[vqx\x7fjmdc"
+    b'>907"%,+\x06\x01\x08\x0f\x1a\x1d\x14\x13'
+    b"\xae\xa9\xa0\xa7\xb2\xb5\xbc\xbb\x96\x91\x98\x9f\x8a\x8d\x84\x83"
+    b"\xde\xd9\xd0\xd7\xc2\xc5\xcc\xcb\xe6\xe1\xe8\xef\xfa\xfd\xf4\xf3"
+)
+
+# mirrortable[i] is the bit reversed version of the byte i
+mirrortable = (
+    b"\x00\x80@\xc0 \xa0`\xe0\x10\x90P\xd00\xb0p\xf0"
+    b"\x08\x88H\xc8(\xa8h\xe8\x18\x98X\xd88\xb8x\xf8"
+    b"\x04\x84D\xc4$\xa4d\xe4\x14\x94T\xd44\xb4t\xf4"
+    b"\x0c\x8cL\xcc,\xacl\xec\x1c\x9c\\\xdc<\xbc|\xfc"
+    b'\x02\x82B\xc2"\xa2b\xe2\x12\x92R\xd22\xb2r\xf2'
+    b"\n\x8aJ\xca*\xaaj\xea\x1a\x9aZ\xda:\xbaz\xfa"
+    b"\x06\x86F\xc6&\xa6f\xe6\x16\x96V\xd66\xb6v\xf6"
+    b"\x0e\x8eN\xce.\xaen\xee\x1e\x9e^\xde>\xbe~\xfe"
+    b"\x01\x81A\xc1!\xa1a\xe1\x11\x91Q\xd11\xb1q\xf1"
+    b"\t\x89I\xc9)\xa9i\xe9\x19\x99Y\xd99\xb9y\xf9"
+    b"\x05\x85E\xc5%\xa5e\xe5\x15\x95U\xd55\xb5u\xf5"
+    b"\r\x8dM\xcd-\xadm\xed\x1d\x9d]\xdd=\xbd}\xfd"
+    b"\x03\x83C\xc3#\xa3c\xe3\x13\x93S\xd33\xb3s\xf3"
+    b"\x0b\x8bK\xcb+\xabk\xeb\x1b\x9b[\xdb;\xbb{\xfb"
+    b"\x07\x87G\xc7'\xa7g\xe7\x17\x97W\xd77\xb7w\xf7"
+    b"\x0f\x8fO\xcf/\xafo\xef\x1f\x9f_\xdf?\xbf\x7f\xff"
+)
+
+
+def checksum(data, start, count):
+    cs = 0
+    for i in range(start, start + count):
+        cs = checksumtable[cs ^ data[i]]
+    return cs
+
+
+MODE_TEXT = "MODE_TEXT"
+MODE_BITMAP = "MODE_BITMAP"
+
+class CatPrinter(Service):
+
+    uuid = StandardUUID(0xAE30)
+
+    _tx = StreamIn(uuid=StandardUUID(0xAE01), timeout=1.0, buffer_size=256)
+
+    def _write_data(self, buf):
+        self._tx.write(buf)
+
+    @property
+    def bitmap_width(self):
+        return 384
+
+    def __init__(self, service=None):
+        super().__init__(service=service)
+        self._mode = None
+
+    @property
+    def mode(self):
+        return self._mode
+
+    @mode.setter
+    def mode(self, value):
+        if value == self.mode:
+            return
+
+        if value == MODE_TEXT:
+            self._write_data(printtext)
+        elif value == MODE_BITMAP:
+            self._write_data(printimage)
+        else:
+            raise ValueError("Invalid mode %r" % value)
+
+        self._mode = value
+
+    def feed_lines(self, lines):
+        buf = bytearray(paperfeed)
+        buf[6] = lines & 0xFF
+        buf[7] = lines >> 8
+        buf[8] = checksum(buf, 6, 2)
+        self._write_data(buf)
+
+    def _print_common(self, text, reverse_bits=True):
+        data = memoryview(text)
+        while data:
+            sz = min(112, len(data))
+            sub_data = data[:sz]
+            data = data[sz:]
+            buf = bytearray(sz + 8)
+            buf[0] = 0x51
+            buf[1] = 0x78
+            buf[2] = 0xA2
+            buf[3] = 0x0
+            buf[4] = sz
+            buf[5] = 0
+            if reverse_bits:
+                buf[6 : 6 + sz] = bytes(mirrortable[c] for c in sub_data)
+            else:
+                buf[6 : 6 + sz] = sub_data
+            buf[6 + sz] = checksum(buf, 6, len(sub_data))
+            buf[6 + sz + 1] = 0xFF
+
+            self._write_data(buf)
+
+    def print_text(self, text):
+        self.mode = MODE_TEXT
+        self._print_common(text.encode("utf-8"))
+
+    def print_line(self, text):
+        self.print_text(text)
+        self._print_common(b"\n")
+
+    def print_bitmap_row(self, data, reverse_bits=True):
+        self.mode = MODE_BITMAP
+        self._print_common(data, reverse_bits)