DailyDuino HexPad 16 — nRF52840 Firmware

A 4×4 BLE + USB HID macropad with 16 WS2812B RGB LEDs, 7 switchable profiles, and a JSON configuration protocol over three transports (USB Serial, USB Raw HID, BLE NUS).

Supported hardware: nice!nano · Tenstar Robot Pro Micro nRF52840 (any board that exposes raw nRF52840 GPIO numbers with an identity pin map).

Features

Feature	Detail
Keys	4×4 matrix, 8 ms per-key debounce
Profiles	7 profiles, switchable via button
LEDs	16× WS2812B — 5 modes per profile (per-key, solid, rainbow, reactive, breathe)
Indicator LEDs	4 LEDs: profile binary display, battery bar, pairing flash, charging sweep
BLE HID	Keyboard + consumer-control, multi-bond
USB HID	Keyboard + consumer-control (always active, no pairing needed)
BLE Battery Service	Standard 0x180F, updated every 60 s
Config transports	USB CDC Serial · USB Raw HID · BLE NUS (same JSON protocol on all three)
Storage	LittleFS on internal flash; auto-format on corruption
Deep sleep	System OFF (~2 µA) after 15 min idle (battery only); any key or button wakes
LED dimming	WS2812B dims to off after 5 min idle, restores on keypress
Battery monitor	ADC on P0.04, 12-bit, 8-sample average, non-linear LiPo curve
Charging detect	Heuristic: USB connected + voltage rising over 2 min
Factory reset	Hold button ≥ 5 s at boot

Default profiles

#	Name	Layout
1	Hex	0-9, A-F hex keypad (orange row + green keys)
2	Numpad	Standard numpad layout (7-8-9-/ · 4-5-6-* · 1-2-3-· · 0-.-Enter-+)
3	Media	Play/Pause, Next, Prev, Stop, Vol+, Vol−, Mute
4-7	Profile 4-7	Empty (distinct LED colours)

Pin map

Uses raw nRF52840 GPIO numbers (P0.xx = 0–31, P1.xx = 32+).
Compiled with board target adafruit:nrf52:pca10056 (identity g_ADigitalPinMap).

GPIO #	nRF52840	nice!nano label	Function
11	P0.11	D7	Row 0 (open-drain scan, ext. 10 kΩ pull-up)
32	P1.00	D6	Row 1 (open-drain scan, ext. 10 kΩ pull-up)
24	P0.24	D5	Row 2 (open-drain scan, ext. 10 kΩ pull-up)
22	P0.22	D4	Row 3 (open-drain scan, ext. 10 kΩ pull-up)
20	P0.20	D3	Col 0 (driven LOW during scan)
17	P0.17	D2	Col 1 (driven LOW during scan)
8	P0.08	D0	Col 2 (driven LOW during scan)
6	P0.06	D1	Col 3 (driven LOW during scan)
10	P0.10	D8	WS2812B DIN
13	P0.13	—	VCC enable (set HIGH at boot to power WS2812B)
9	P0.09	D9	Indicator LED bit 0 (LSB)
2	P0.02	D10	Indicator LED bit 1
29	P0.29	D15	Indicator LED bit 2
31	P0.31	D14	Indicator LED bit 3 (MSB)
4	P0.04	A0	Battery ADC (AIN2, voltage divider ÷2)
36	P1.04	A1	Profile button (INPUT_PULLUP, active LOW)

Matrix wiring

Diode direction: column → row (anode on column wire, cathode on row wire).

Rows are scanned open-drain: each row pin switches between OUTPUT LOW (scan active) and INPUT (high-Z idle) to avoid bus conflicts. Column pins use INPUT_PULLUP (internal ~13 kΩ) plus external 10 kΩ pull-ups (combined ~5.6 kΩ).

A pressed key forward-biases the diode and pulls the column pin LOW.

WS2812B LED strip wiring (snake)

Key row 0 (top) ←  pixels 15 14 13 12
Key row 1       →  pixels  8  9 10 11
Key row 2       ←  pixels  7  6  5  4
Key row 3 (bot) →  pixels  0  1  2  3

Strip connector attaches at physical bottom-left.

Indicator LED binary encoding

Pattern	Profile
○○○●	1
○○●○	2
○○●●	3
○●○○	4
○●○●	5
○●●○	6
○●●●	7

LED 0 (LSB) slow-pulses when battery ≤ 10 %. All 4 LEDs flash ~8 Hz in pairing mode. Double-tap shows a 3-second battery bar (1–4 LEDs filled).

Profile button gestures

Gesture	Action
Single tap	Cycle to next profile (1 → 2 → … → 7 → 1)
Double tap	Show battery level for 3 s
Hold 3 s	Enter BLE pairing mode (clears bonds, restarts advertising)
Release after long hold	Exit pairing mode

Build

Required tools & libraries

Tool / Library	Version	Notes
arduino-cli or Arduino IDE 2	any
Adafruit nRF52 BSP	≥ 1.6 (1.7.0 tested)	includes Bluefruit + TinyUSB
ArduinoJson	≥ 7.0
Adafruit NeoPixel	any

BSP board manager URL:

https://adafruit.github.io/arduino-board-index/package_adafruit_index.json

Compile + flash (arduino-cli)

# Compile
arduino-cli compile --fqbn adafruit:nrf52:pca10056 --output-dir build HexPad-nRF52840.ino

# Convert to UF2
python3 /path/to/uf2conv.py \
    --family 0xADA52840 --base 0x26000 \
    build/HexPad-nRF52840.ino.hex \
    -o build/HexPad-nRF52840.uf2

uf2conv.py ships with the Adafruit nRF52 BSP at: ~/.arduino15/packages/adafruit/hardware/nrf52/<version>/tools/uf2conv/uf2conv.py

Board target must be adafruit:nrf52:pca10056 (Nordic nRF52840 DK). This board definition has an identity g_ADigitalPinMap so raw GPIO numbers in code map directly to physical pins. Using adafruit:nrf52:feather52840 will map all GPIO numbers wrong.

Flash

Enter the bootloader (double-tap reset — LED pulses). A mass-storage drive appears. Copy HexPad-nRF52840.uf2 onto it; device reboots automatically.

Factory reset

Hold the profile button while plugging in USB (or at power-on). Keep holding for 5 seconds until the indicator LEDs blink 3 times. All profiles reset to defaults and the active profile is saved.

USB device identity

Field	Value
VID / PID	`0x1209` / `0xDD16`
Manufacturer	DailyDuino
Product	DailyDuino Hexpad 16
HID reports	Report ID 1: keyboard · ID 2: consumer · ID 3: vendor config (32 B)

BLE

Field	Value
Device name	`DailyDuino Hexpad 16`
TX power	+4 dBm
BLE ATT MTU	247 bytes (BANDWIDTH_MAX, HVN queue = 3)
Advertising	Fast 30 s, then slow; restarts on disconnect
NUS TXD	`6E400003-B5A3-F393-E0A9-E50E24DCCA9E` (notify)
NUS RXD	`6E400002-B5A3-F393-E0A9-E50E24DCCA9E` (write)
Battery Service	UUID `0x180F`

Config protocol

All three transports speak the same line-delimited JSON protocol (newline \n as message terminator).

Transport	How to connect
USB CDC Serial	115200 baud — any serial terminal
USB Raw HID	Report ID 3, 32-byte reports — vendor `0xFF60`, usage `0x61`
BLE NUS	Write to RXD characteristic; responses arrive on TXD notifications

Commands

Command	Required fields	Response
`info`	—	Device name, firmware, proto version, profile count, battery %
`get_profile`	`profile` (0-6, optional)	Full profile: name, LED config, all 16 key bindings, per-key LED colors
`set_key`	`profile`, `key` (0-15), `action` object	`{"ok":true}`
`set_led`	`profile`, any of: `enabled`, `brightness`, `mode`, `color`, `anim_speed`	`{"ok":true}`
`set_led_color`	`profile`, `key` (0-15), `rgb` ([r,g,b])	`{"ok":true}`
`set_profile_name`	`profile`, `name`	`{"ok":true}`
`switch_profile`	`profile` (0-6)	`{"ok":true}`
`get_battery`	—	`pct`, `mv`, `charging`, `usb`
`save`	—	Persists current config to LittleFS
`reset_defaults`	—	Restores factory defaults and saves
`sleep`	—	Enters System OFF deep sleep

All requests may include an "id" field; the value is echoed back in the response.

Key action types

Type	Extra fields	Description
`none`	—	No action
`key`	`keycode`, `mods`	Single HID keycode with modifier mask
`combo`	`keys` (array), `mods`	Multiple keycodes sent simultaneously
`text`	`text` (string)	Types a string via ASCII→HID lookup
`consumer`	`consumer` (uint16)	HID consumer-control usage code
`macro`	`steps` (array)	Sequence of press/release/tap/delay steps

Modifier mask bits: LCTRL=0x01 LSHIFT=0x02 LALT=0x04 LGUI=0x08 RCTRL=0x10 RSHIFT=0x20 RALT=0x40 RGUI=0x80

LED modes

Value	Name	Description
0	per-key	Individual RGB per key stored in profile
1	solid	All keys one colour
2	rainbow	Hue cycle animation across all keys
3	reactive	Keys flash white on press, fade to base colour
4	breathe	All keys pulse in/out at `anim_speed` rate

Example session

→ {"cmd":"info"}
← {"ok":true,"name":"DailyDuino Hexpad 16","firmware":"3.0.0-nrf","proto":2,"profiles":7,"keys":16,"leds":16,"profile":0,"battery":85}

→ {"cmd":"get_profile","profile":0}
← {"ok":true,"profile":0,"data":{"name":"Hex","led":{...},"keys":[...],"led_colors":[...]}}

→ {"cmd":"set_key","profile":0,"key":0,"action":{"type":"key","keycode":4,"mods":0}}
← {"ok":true}

→ {"cmd":"save"}
← {"ok":true}

Power

Threshold	Value
Deep sleep trigger	15 min idle, battery only (USB connected = no sleep)
LED dim trigger	5 min idle
Battery full	4200 mV
Battery empty	3000 mV
Low battery warning	≤ 3300 mV (~10 %)
Wake sources	Any column pin LOW or button pin LOW (GPIO SENSE)

Source files

File	Purpose
`HexPad-nRF52840.ino`	Main sketch — setup, loop, key + button event dispatch
`Config.h / .cpp`	Pin constants, data structures, LittleFS persistence, factory defaults
`Matrix.h / .cpp`	4×4 scan with open-drain rows, 8 ms debounce
`HIDOutput.h / .cpp`	BLE HID + USB HID reports, BLE NUS, USB Raw HID, held-key tracking
`LedControl.h / .cpp`	WS2812B driver, 5 animation modes, snake LED map, idle dimming
`Indicator.h / .cpp`	4-LED indicator: profile, battery, pairing, charging, low-batt
`Button.h / .cpp`	Debounced single / double / long-press state machine
`Power.h / .cpp`	Battery ADC, BLE BAS, charging heuristic, deep sleep
`Protocol.h / .cpp`	Transport-agnostic JSON command dispatcher
`INTERFACE.md`	Config protocol reference for client developers

Name		Name	Last commit message	Last commit date
.gitignore		.gitignore
Button.cpp		Button.cpp
Button.h		Button.h
Config.cpp		Config.cpp
Config.h		Config.h
HIDOutput.cpp		HIDOutput.cpp
HIDOutput.h		HIDOutput.h
HexPad-nRF52840.ino		HexPad-nRF52840.ino
INTERFACE.md		INTERFACE.md
Indicator.cpp		Indicator.cpp
Indicator.h		Indicator.h
LICENSE		LICENSE
LedControl.cpp		LedControl.cpp
LedControl.h		LedControl.h
Matrix.cpp		Matrix.cpp
Matrix.h		Matrix.h
Power.cpp		Power.cpp
Power.h		Power.h
Protocol.cpp		Protocol.cpp
Protocol.h		Protocol.h
README.md		README.md

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DailyDuino HexPad 16 — nRF52840 Firmware

Features

Default profiles

Pin map

Matrix wiring

WS2812B LED strip wiring (snake)

Indicator LED binary encoding

Profile button gestures

Build

Required tools & libraries

Compile + flash (arduino-cli)

Flash

Factory reset

USB device identity

BLE

Config protocol

Commands

Key action types

LED modes

Example session

Power

Source files

About

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Repository files navigation

DailyDuino HexPad 16 — nRF52840 Firmware

Features

Default profiles

Pin map

Matrix wiring

WS2812B LED strip wiring (snake)

Indicator LED binary encoding

Profile button gestures

Build

Required tools & libraries

Compile + flash (arduino-cli)

Flash

Factory reset

USB device identity

BLE

Config protocol

Commands

Key action types

LED modes

Example session

Power

Source files

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