Found on hardware: the Tools Server field was pointed at Immich's own
port instead of the frame server's, so /frame/image was actually hitting
Immich and getting back a small error response (~10KB) instead of a
192,000-byte frame. epd_display_stream() logged a size-mismatch warning
but called epd_turn_on_display() anyway, physically refreshing the panel
with a buffer that was ~95% whatever was left over from before -- visible
as "garbage" on screen, overwriting a previously-good image.
epd_display_stream() now returns ESP_ERR_INVALID_SIZE instead of
refreshing when the stream doesn't supply exactly EPD_FRAME_BYTES. Since
this check happens before epd_turn_on_display() is ever called, the
pixel data that *did* arrive only ever reached the panel's internal RAM
over SPI, not the physically visible display, so aborting here leaves the
screen exactly as it was.
This also means fetch_and_display() failing now always implies the panel
was never touched -- simplified frame_client_run() accordingly (dropped
the now-always-true/false out-param that used to distinguish "failed
before vs. during streaming", and always shows the FAILED status screen
on any fetch/display error, since it's now guaranteed safe to do so).
Two crashes found flashing to real hardware:
- epd_display_stream's 4KB SPI chunk buffer was a stack local, but the
default main task stack (3584 bytes) is smaller than that alone --
Guru Meditation stack protection fault. Made it static instead, and
bumped CONFIG_ESP_MAIN_TASK_STACK_SIZE to 8192 for headroom in the rest
of the boot call chain (provisioning -> QR render -> eventually the
HTTP fetch cycle all run in this one task).
- epd_wait_busy() polled with a 1ms vTaskDelay, which rounds down to 0
FreeRTOS ticks at the default 100Hz tick rate -- so it never actually
blocked, tight-spinning the CPU for the panel's real refresh time
(15-30+s for a full-color pass) and starving the idle task long enough
to trip the 5s task watchdog. Bumped to 20ms, safely >=1 tick regardless
of tick rate.
Also updates the EPD pin defaults to the board's actual wiring
(CLK=20 MOSI=19 CS=18 DC=9 RST=10 BUSY=11), confirmed working on hardware.
Vendors two small MIT/BSD-3-Clause libraries rather than hand-rolling
either: Nayuki's qrcodegen (QR matrix generation) and Waveshare's Font24
bitmap table from their e-Paper repo (same repo the epd7in3e driver came
from) for rendering readable text on the panel.
qr_onboarding_show() builds a standard WIFI:T:WPA;S:...;P:...;; payload,
rasterizes the QR module matrix plus the SSID and password as plaintext
underneath (for anyone provisioning from a device that can't scan a QR)
onto a malloc'd frame buffer, and pushes it to the panel via
epd_display_buffer(). The buffer is heap-allocated on demand rather than
statically reserved, since 192KB held permanently in BSS would eat into
the RAM budget the HTTP fetch path (task 6) is specifically trying to keep
free.
Wired into wifi_provisioning_start() before the softAP comes up, so the
join instructions are already on-screen by the time the network is
joinable.
Ports Waveshare's official EPD_7in3e.c register/refresh sequence (the
panel has no public datasheet, so their reference driver is the source of
truth) to an ESP-IDF component using spi_master + gpio instead of the
bcm2835/RPi hardware abstraction the reference targets.
Unlike the reference driver, which toggles CS around every single byte,
this holds CS low for each logical command/data phase and DMAs pixel data
in 4KB chunks -- sending ~192,000 individual one-byte SPI transactions
would make a full refresh impractically slow.
Exposes a streaming API (epd_display_stream, pulling chunks from a
caller-supplied read_fn) so the eventual HTTP fetch path can feed the panel
without holding a full ~192KB frame in RAM, plus an in-memory convenience
wrapper (epd_display_buffer) for cases like the upcoming QR code screen
where buffering the whole frame is fine.
Wired into wifi_provisioning_start() as an init + white-clear for now, to
prove the driver builds/links/runs at the right point in the boot sequence
ahead of the actual QR code content.
Moves the existing ESP-IDF captive_portal example into firmware/ to make
room for the new FastAPI server and project docs, ahead of building out the
full ESPresso Frame project (ESP32-C6 + Immich-backed e-ink photo frame).
tfaour