226 lines
9.3 KiB
Python
226 lines
9.3 KiB
Python
"""Reference SSD168x SPI decoder — pure Python, no QEMU, no DOM.
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This is the **specification** the Velxio frontend emulator must match.
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It exists alongside the actual TS implementation so we can:
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1. Validate the SPI command set against published datasheets without
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spinning up Vite / Vitest / a browser.
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2. Drive the same byte streams through this decoder and the future TS
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decoder and assert the resulting framebuffers are identical.
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3. Catch SSD1681 / SSD1675 / SSD1680 / SSD1683 quirks early — every
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panel that uses a SSD168x part funnels through this one decoder.
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The decoder is intentionally minimal: it consumes the bytes the
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GxEPD2 / Adafruit_EPD libraries emit, builds a 1-bit-per-pixel
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framebuffer, and exposes ``flush()`` to capture the latched image when
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the firmware sends 0x20 ACTIVATE.
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References:
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- SSD1681 datasheet (Adafruit mirror):
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https://cdn-learn.adafruit.com/assets/assets/000/099/573/original/SSD1681.pdf
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- ESP-BSP command header:
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https://github.com/espressif/esp-bsp/blob/master/components/lcd/esp_lcd_ssd1681/esp_lcd_ssd1681_commands.h
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"""
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from __future__ import annotations
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from dataclasses import dataclass, field
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from typing import Callable, List, Optional
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# ── Command opcodes (SSD1681; SSD1675/1680/1683 share these) ─────────────────
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CMD_DRIVER_OUTPUT_CTRL = 0x01
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CMD_GATE_DRIVING_VOLTAGE = 0x03
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CMD_SOURCE_DRIVING_VOLT = 0x04
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CMD_DEEP_SLEEP = 0x10
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CMD_DATA_ENTRY_MODE = 0x11
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CMD_SW_RESET = 0x12
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CMD_TEMP_SENSOR = 0x18
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CMD_MASTER_ACTIVATION = 0x20
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CMD_DISP_UPDATE_CTRL_1 = 0x21
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CMD_DISP_UPDATE_CTRL_2 = 0x22
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CMD_WRITE_BLACK_VRAM = 0x24
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CMD_WRITE_RED_VRAM = 0x26
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CMD_WRITE_VCOM_REG = 0x2C
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CMD_WRITE_LUT = 0x32
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CMD_BORDER_WAVEFORM = 0x3C
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CMD_END_OPTION = 0x3F
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CMD_SET_RAMX_RANGE = 0x44
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CMD_SET_RAMY_RANGE = 0x45
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CMD_SET_RAMX_COUNTER = 0x4E
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CMD_SET_RAMY_COUNTER = 0x4F
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# ── Framebuffer model ────────────────────────────────────────────────────────
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@dataclass
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class Frame:
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"""Composed B/W (and optionally red) frame, ready to render.
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``pixels`` is a list of ints, one per pixel, in the panel-native
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palette: 0 = black, 1 = white, 2 = red (only when red plane was
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written). Length is always ``width * height``.
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"""
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width: int
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height: int
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pixels: List[int]
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# ── Decoder ──────────────────────────────────────────────────────────────────
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@dataclass
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class SSD168xDecoder:
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"""SPI-byte stream → latched framebuffer.
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Usage:
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d = SSD168xDecoder(width=200, height=200)
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for byte, dc in spi_trace: # dc=False (LOW) for cmd, True for data
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d.feed(byte, dc)
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# When the firmware sends 0x20 ACTIVATE, on_flush is invoked.
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"""
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width: int
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height: int
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on_flush: Optional[Callable[[Frame], None]] = None
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# Internal state
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bw_ram: bytearray = field(init=False)
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red_ram: bytearray = field(init=False)
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_current_cmd: int = -1
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_params: List[int] = field(default_factory=list)
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_ram_target: str = "bw" # 'bw' or 'red' — which plane we're writing
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_x_byte: int = 0 # current X position (in bytes — 8 px/byte)
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_y: int = 0 # current Y position (scanline)
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_xrange: tuple = (0, 0) # (start_byte, end_byte)
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_yrange: tuple = (0, 0) # (start_y, end_y)
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_entry_mode: int = 0x03 # x+ y+ x-first (default for most drivers)
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refreshed_count: int = 0 # how many MASTER_ACTIVATIONs we've seen
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unknown_cmds: List[int] = field(default_factory=list)
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in_deep_sleep: bool = False
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def __post_init__(self) -> None:
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bytes_per_row = (self.width + 7) // 8
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self.bw_ram = bytearray([0xFF] * (bytes_per_row * self.height)) # white
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self.red_ram = bytearray([0x00] * (bytes_per_row * self.height)) # no red
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self._xrange = (0, bytes_per_row - 1)
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self._yrange = (0, self.height - 1)
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# ── Public API ─────────────────────────────────────────────────────
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def feed(self, byte: int, dc_high: bool) -> None:
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"""Process one SPI byte. ``dc_high`` mirrors the DC pin (False = command)."""
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if not dc_high:
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self._begin_command(byte)
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else:
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self._handle_data(byte)
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def reset(self) -> None:
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"""Clear all state — equivalent to a hardware RST low pulse."""
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bytes_per_row = (self.width + 7) // 8
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self.bw_ram = bytearray([0xFF] * (bytes_per_row * self.height))
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self.red_ram = bytearray([0x00] * (bytes_per_row * self.height))
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self._current_cmd = -1
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self._params = []
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self._ram_target = "bw"
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self._x_byte = 0
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self._y = 0
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self.in_deep_sleep = False
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def compose_frame(self) -> Frame:
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"""Build a Frame from the latched RAM planes (red wins over black)."""
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bytes_per_row = (self.width + 7) // 8
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pixels: List[int] = [0] * (self.width * self.height)
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for y in range(self.height):
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for xb in range(bytes_per_row):
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b_byte = self.bw_ram[y * bytes_per_row + xb]
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r_byte = self.red_ram[y * bytes_per_row + xb]
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for bit in range(8):
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x = xb * 8 + bit
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if x >= self.width:
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break
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mask = 0x80 >> bit
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is_red = bool(r_byte & mask)
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is_white = bool(b_byte & mask)
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pixels[y * self.width + x] = 2 if is_red else (1 if is_white else 0)
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return Frame(self.width, self.height, pixels)
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# ── Internal: command / data dispatch ──────────────────────────────
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def _begin_command(self, cmd: int) -> None:
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self._current_cmd = cmd
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self._params = []
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if cmd == CMD_SW_RESET:
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self.reset()
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return
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if cmd == CMD_MASTER_ACTIVATION:
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self.refreshed_count += 1
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frame = self.compose_frame()
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if self.on_flush:
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self.on_flush(frame)
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return
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if cmd == CMD_WRITE_BLACK_VRAM:
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self._ram_target = "bw"
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return
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if cmd == CMD_WRITE_RED_VRAM:
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self._ram_target = "red"
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return
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if cmd in (
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# Known commands that consume data — handled in _handle_data.
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CMD_DRIVER_OUTPUT_CTRL, CMD_GATE_DRIVING_VOLTAGE,
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CMD_SOURCE_DRIVING_VOLT, CMD_DEEP_SLEEP, CMD_DATA_ENTRY_MODE,
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CMD_TEMP_SENSOR, CMD_DISP_UPDATE_CTRL_1, CMD_DISP_UPDATE_CTRL_2,
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CMD_WRITE_VCOM_REG, CMD_WRITE_LUT, CMD_BORDER_WAVEFORM,
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CMD_END_OPTION, CMD_SET_RAMX_RANGE, CMD_SET_RAMY_RANGE,
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CMD_SET_RAMX_COUNTER, CMD_SET_RAMY_COUNTER,
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):
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return
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# Anything else: log and silently consume so init flows complete.
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self.unknown_cmds.append(cmd)
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def _handle_data(self, byte: int) -> None:
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cmd = self._current_cmd
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params = self._params
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params.append(byte)
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if cmd == CMD_DEEP_SLEEP and len(params) == 1:
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self.in_deep_sleep = byte != 0
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elif cmd == CMD_DATA_ENTRY_MODE and len(params) == 1:
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self._entry_mode = byte
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elif cmd == CMD_SET_RAMX_RANGE and len(params) == 2:
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self._xrange = (params[0], params[1])
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self._x_byte = params[0]
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elif cmd == CMD_SET_RAMY_RANGE and len(params) == 4:
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self._yrange = (params[0] | (params[1] << 8),
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params[2] | (params[3] << 8))
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self._y = self._yrange[0]
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elif cmd == CMD_SET_RAMX_COUNTER and len(params) == 1:
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self._x_byte = byte
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elif cmd == CMD_SET_RAMY_COUNTER and len(params) == 2:
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self._y = params[0] | (params[1] << 8)
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elif cmd == CMD_WRITE_BLACK_VRAM:
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self._write_ram_byte(self.bw_ram, byte)
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elif cmd == CMD_WRITE_RED_VRAM:
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self._write_ram_byte(self.red_ram, byte)
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# Other commands silently buffer their parameters.
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def _write_ram_byte(self, plane: bytearray, byte: int) -> None:
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bytes_per_row = (self.width + 7) // 8
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if 0 <= self._x_byte < bytes_per_row and 0 <= self._y < self.height:
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plane[self._y * bytes_per_row + self._x_byte] = byte
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# Auto-increment per data_entry_mode (default x+, then y+ at end of row).
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x_inc = (self._entry_mode & 0x01) == 0x01 # bit0: 1 = X+
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# entry_mode bit1: Y direction; bit2: which counter advances first.
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# For the default 0x03, X advances; once it hits xrange[1], wrap and Y++.
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if x_inc:
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if self._x_byte < self._xrange[1]:
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self._x_byte += 1
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else:
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self._x_byte = self._xrange[0]
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self._y += 1
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else:
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if self._x_byte > self._xrange[0]:
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self._x_byte -= 1
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else:
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self._x_byte = self._xrange[1]
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self._y += 1
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