klipper-dgus/klippy/extras/display/st7920.py

# Support for ST7920 (128x64 graphics) LCD displays
#
# Copyright (C) 2018  Kevin O'Connor <kevin@koconnor.net>
#
# This file may be distributed under the terms of the GNU GPLv3 license.
import logging

BACKGROUND_PRIORITY_CLOCK = 0x7fffffff00000000

# Spec says 72us, but faster is possible in practice
ST7920_CMD_DELAY  = .000020
ST7920_SYNC_DELAY = .000045

class ST7920:
    char_right_arrow = '\x1a'
    def __init__(self, config):
        printer = config.get_printer()
        # pin config
        ppins = printer.lookup_object('pins')
        pins = [ppins.lookup_pin(config.get(name + '_pin'))
                for name in ['cs', 'sclk', 'sid']]
        mcu = None
        for pin_params in pins:
            if mcu is not None and pin_params['chip'] != mcu:
                raise ppins.error("st7920 all pins must be on same mcu")
            mcu = pin_params['chip']
        self.pins = [pin_params['pin'] for pin_params in pins]
        self.mcu = mcu
        self.oid = self.mcu.create_oid()
        self.mcu.register_config_callback(self.build_config)
        self.send_data_cmd = self.send_cmds_cmd = None
        self.is_extended = False
        # framebuffers
        self.text_framebuffer = (bytearray(' '*64), bytearray('~'*64), 0x80)
        self.glyph_framebuffer = (bytearray(128), bytearray('~'*128), 0x40)
        self.graphics_framebuffers = [(bytearray(32), bytearray('~'*32), i)
                                      for i in range(32)]
        self.framebuffers = ([self.text_framebuffer, self.glyph_framebuffer]
                             + self.graphics_framebuffers)
    def build_config(self):
        self.mcu.add_config_cmd(
            "config_st7920 oid=%u cs_pin=%s sclk_pin=%s sid_pin=%s"
            " sync_delay_ticks=%d cmd_delay_ticks=%d" % (
                self.oid, self.pins[0], self.pins[1], self.pins[2],
                self.mcu.seconds_to_clock(ST7920_SYNC_DELAY),
                self.mcu.seconds_to_clock(ST7920_CMD_DELAY)))
        cmd_queue = self.mcu.alloc_command_queue()
        self.send_cmds_cmd = self.mcu.lookup_command(
            "st7920_send_cmds oid=%c cmds=%*s", cq=cmd_queue)
        self.send_data_cmd = self.mcu.lookup_command(
            "st7920_send_data oid=%c data=%*s", cq=cmd_queue)
    def send(self, cmds, is_data=False, is_extended=False):
        cmd_type = self.send_cmds_cmd
        if is_data:
            cmd_type = self.send_data_cmd
        elif self.is_extended != is_extended:
            add_cmd = 0x22
            if is_extended:
                add_cmd = 0x26
            cmds = [add_cmd] + cmds
            self.is_extended = is_extended
        cmd_type.send([self.oid, cmds], reqclock=BACKGROUND_PRIORITY_CLOCK)
        #logging.debug("st7920 %d %s", is_data, repr(cmds))
    def flush(self):
        # Find all differences in the framebuffers and send them to the chip
        for new_data, old_data, fb_id in self.framebuffers:
            if new_data == old_data:
                continue
            # Find the position of all changed bytes in this framebuffer
            diffs = [[i, 1] for i, (nd, od) in enumerate(zip(new_data, old_data))
                     if nd != od]
            # Batch together changes that are close to each other
            for i in range(len(diffs)-2, -1, -1):
                pos, count = diffs[i]
                nextpos, nextcount = diffs[i+1]
                if pos + 5 >= nextpos and nextcount < 16:
                    diffs[i][1] = nextcount + (nextpos - pos)
                    del diffs[i+1]
            # Transmit changes
            for pos, count in diffs:
                count += pos & 0x01
                count += count & 0x01
                pos = pos & ~0x01
                chip_pos = pos >> 1
                if fb_id < 0x40:
                    # Graphics framebuffer update
                    self.send([0x80 + fb_id, 0x80 + chip_pos], is_extended=True)
                else:
                    self.send([fb_id + chip_pos])
                self.send(new_data[pos:pos+count], is_data=True)
            old_data[:] = new_data
    def init(self):
        cmds = [0x24, # Enter extended mode
                0x40, # Clear vertical scroll address
                0x02, # Enable CGRAM access
                0x26, # Enable graphics
                0x22, # Leave extended mode
                0x02, # Home the display
                0x06, # Set positive update direction
                0x0c] # Enable display and hide cursor
        self.send(cmds)
        self.flush()
    def load_glyph(self, glyph_id, data):
        if len(data) > 32:
            data = data[:32]
        pos = min(glyph_id * 32, 96)
        self.glyph_framebuffer[0][pos:pos+len(data)] = data
    def write_text(self, x, y, data):
        if x + len(data) > 16:
            data = data[:16 - min(x, 16)]
        pos = [0, 32, 16, 48][y] + x
        self.text_framebuffer[0][pos:pos+len(data)] = data
    def write_graphics(self, x, y, row, data):
        if x + len(data) > 16:
            data = data[:16 - min(x, 16)]
        gfx_fb = y * 16 + row
        if gfx_fb >= 32:
            gfx_fb -= 32
            x += 16
        self.graphics_framebuffers[gfx_fb][0][x:x+len(data)] = data
    def clear(self):
        self.text_framebuffer[0][:] = ' '*64
        zeros = bytearray(32)
        for new_data, old_data, fb_id in self.graphics_framebuffers:
            new_data[:] = zeros