A 37 mm box on a CR2032 that plugs into the RZ67's electrical remote port. An Android or iPhone app fires the shutter over Bluetooth, holds it open for bulb, or runs a countdown. The board sleeps between uses and wakes on a button press.
The project started in 2023 on a Seeed XIAO ESP32-C3 and a Fritzing schematic. A custom ESP32-C3 board on a LiPo followed in 2025 and went through two fabricated revisions. The coin-cell board is the third design; rev A is its first order, after several layout rounds.
Board, Android app and iPhone app each have their own repository, releases and issue tracker.
An nRF54L15 module on a CR2032, with no charger, regulator or power switch. Two isolated PhotoMOS channels close the camera's S1/S2 contacts. Zephyr firmware, updates over Bluetooth.
Android app. Connects to the trigger on its own and reconnects when the link drops.
iPhone app in SwiftUI, same modes as the Android app. Not in the App Store yet, so it has to be built in Xcode.
The RZ67's remote port exposes two contacts, S1 and S2. Shorting them to camera ground fires the shutter. The trigger does that through two PhotoMOS relays, so the cell and the camera share no ground.
Four pins, viewed from the front of the camera.
| Pin | Signal |
|---|---|
| 1 | 6 V, not connected |
| 2 | GND |
| 3 | S1 switch |
| 4 | S2 switch |
No power switch. The chip sleeps until the button wakes it.
| State | What happens |
|---|---|
| Asleep | About 0.7 µA by spec. A press wakes it. |
| Awake | Advertises as OpenRZ67 for 5 minutes, then sleeps if no phone connects. |
| Connected | Stays on while the app holds the link. After a disconnect, 5 more minutes to reconnect. |
| Hold 3 s | Off, until the next press. |
Commands are single bytes written without response. Value = button × 10 + state.
| Byte | Action |
|---|---|
| 11 | Fire shutter, 100 ms pulse |
| 21 / 20 | Start / end bulb |
| 31 / 30 | Start / cancel 10 s countdown |
| 3 n 1 | Countdown of n seconds |
| The board also exposes the standard Device Information Service (firmware revision), a read/notify characteristic with the cell voltage in millivolts, and the standard Battery Service (0x180F) with the level in percent. | |
Mode selector at the top, one large release button. Light or dark theme follows the system setting.
For now you order the board assembled from JLCPCB yourself; the rest plugs in. A kit with a finished board, and perhaps a printed case, may come once the design has settled. Rev A has not been signed off yet, so read the nrf README before ordering.
Upload the Gerber zip, BOM and position file from nrf/kicad/out to JLCPCB, with assembly on both sides.
Build it with the nRF Connect SDK, then flash once over the SWD connector with a Raspberry Pi Pico 2 running Raspberry Pi's debugprobe firmware, cell out. After that, updates go over Bluetooth. Steps in nrf/firmware.
A Qwiic / STEMMA QT pigtail with female Dupont ends, pushed onto the camera pins and taped: black on pin 2 (GND), blue on pin 3 (S1), yellow on pin 4 (S2). The red wire is not connected on the board. Double-check orientation before you plug it in.
Get the files from nrf/case: shell and sliding floor in ABS, no supports, and a light pipe in clear filament. The CR2032 goes in + side up.
Grab the APK from releases. Press the button and the app connects on its own. On iPhone, build openrz67-ios in Xcode until it is in the App Store.
Same Bluetooth protocol, so the apps work with any of these without changes.
The previous design, from 2025: an ESP32-C3 on a 250 mAh LiPo with USB-C charging, PlatformIO firmware and its own printed case. Bigger than the coin-cell board. Rev 1 was ordered in September 2025; rev 2 has been in use since September 2026.
The coin-cell circuit with off-the-shelf parts and through-hole soldering: a Seeed XIAO nRF54L15, two DIP PhotoMOS relays and a small LiPo. Same firmware, flashed over the XIAO's USB-C.
2023. Dev board, Fritzing schematic, first version of the BLE protocol and the Android app.
Rev 1 ordered September 2025, drawn in EasyEDA; it worked, but its LGS5500 charger led to a new power path. Rev 2 with PhotoMOS relays, BQ25185 charger and TPS63031 buck-boost, in use since September 2026.
Boards ordered 2026-10-10. Board, firmware and case under test.
The iOS app works against the trigger. Next: an Apple developer account and review.
Assembled board, with or without a printed case, once rev A has settled.
Other parts of the RZ67 system may follow.