Space-scroll-demonstration.mp4

Space Scroll

High-resolution wireless scroll dial for ESP32-C6 using an AS5600 magnetic encoder, BLE HID Resolution Multiplier (NimBLE), WS2812 status LED, and LiPo battery monitoring.

Hardware

Function	GPIO
AS5600 SCL	19
AS5600 SDA	20
WS2812 data	8
Battery divider	5 (R1=100K to Li+, R2=100K to GND)

Dependencies

Managed via main/idf_component.yml:

• espp/as5600^1.1.4 — magnetic encoder driver
• espp/i2c^1.1.4 — I2C helper used by the AS5600 example API
• espressif/led_strip^3.0.0 — WS2812 driver

Install or refresh dependencies:

idf.py add-dependency "espp/as5600^1.1.4"
idf.py add-dependency "espp/i2c^1.1.4"
idf.py add-dependency "espressif/led_strip^3.0.0"

Build

Development build (verbose logging):

idf.py set-target esp32c6
idf.py build flash monitor

Release build (reduced logging):

idf.py -DSDKCONFIG_DEFAULTS="sdkconfig.defaults;sdkconfig.defaults.release" build

BLE HID hi-res scroll dial

Advertises as SpaceScroll (BLE HID mouse with Resolution Multiplier). Dial rotation maps AS5600 angle changes to fine-grained scroll wheel units; Linux/Windows negotiate hi-res via the HID feature report (same model as Engineer Bo’s Full Scroll Dial).

Sensitivity in main/board_config.h:

• BOARD_SCROLL_DEG_PER_LINE — dial degrees per one full legacy scroll line (higher = slower; default 12.0 → 10 hi-res units per degree, 120 units per line)
• BOARD_HID_HI_RES_ENABLE_MS — delay after connect before enabling the multiplier feature report (default 500)

The project includes a patched local components/esp_hid so NimBLE registers mouse feature reports (required for host hi-res negotiation; stock ESP-IDF drops them). After changing components/esp_hid, run idf.py fullclean build so CMake picks up the override instead of the IDF copy.

After flashing, remove and re-pair so the host loads the new report map and product ID:

bluetoothctl
# remove XX:XX:XX:XX:XX:XX
# scan on
# pair/trust/connect SpaceScroll

Verify on Linux

sudo evtest
# pick SpaceScroll, rotate dial slowly

Hi-res working: REL_WHEEL_HI_RES shows small varying values (±1, ±2, ±5…). REL_WHEEL is 0 most of the time (±1 only when accumulated hi-res crosses 120).

Broken (multiplier not negotiated): every event has REL_WHEEL=±1 and REL_WHEEL_HI_RES=±120 together — re-pair and check serial log for HID hi-res scroll enabled.

Optional udev hwdb if scroll feels wrong on some setups (ESP32-BLE-Mouse #78):

# /etc/udev/hwdb.d/11-spacescroll-mouse.hwdb
mouse:*:name:SpaceScroll:
 MOUSE_WHEEL_CLICK_ANGLE=7.5
 MOUSE_WHEEL_CLICK_COUNT=120

Then sudo systemd-hwdb update && sudo udevadm trigger.

Confirm descriptor includes Resolution Multiplier (0x48):

for d in /sys/bus/hid/devices/*; do
  grep -q SpaceScroll "$d/uevent" 2>/dev/null || continue
  xxd "$d/report_descriptor"
done

Logging

• Debug/dev (sdkconfig.defaults): LOG_DEFAULT_LEVEL_DEBUG — startup details and ESP_LOGD dial samples
• Release (sdkconfig.defaults.release): LOG_DEFAULT_LEVEL_WARN — errors and warnings only

Battery divider values are defined in main/board_config.h (R1=100K, R2=220K → ratio ≈1.45).

License

MIT — see LICENSE.