RotaryCell / build guide

Add the LilyGO connections

Add and label each group separately. The overview and close photographs below show the connector orientation and routing used in the working build.

Four prepared LilyGO harnesses laid out before installation

Four harnesses attach to the LilyGO. From left to right in the photograph:

Harness	Wire identification used in this build
Charging input	10 cm red and black pair with red two-position connector
21700 battery	10 cm pair; yellow is unswitched battery positive and black is battery negative
AG1171 carrier power	10 cm red and black pair with white two-position connector
AG1171 carrier signals	Four 10 cm signal wires in a white connector; the blue conductor marks orientation

Throughout this build, black is negative and yellow identifies unswitched battery positive. The blue wire in the four-conductor signal harness is an orientation marker; compare its position with the completed-board photographs before inserting the contacts into the housing.

The current-carrying red, yellow and black conductors shown here are 24 AWG. The signal-only conductors are 28 AWG. These are the gauges used in the working build; the signal currents themselves are small.

Battery and protected-system power

Connect the prepared 21700 leads to the LilyGO battery-positive and BATN points formerly used by the holder. The AG1171 carrier receives positive power from the LilyGO VBAT pad and returns through LilyGO system GND. Its ground does not connect directly to BATN.

Yellow battery-positive and black battery-negative leads attached after removal of the original holder

The yellow and black battery leads leave opposite ends of the former holder area. Keeping both at 10 cm provides enough lead to reach the 21700 without leaving a large loop inside the phone.

Audio and tone

The Audio/Reset A4 harness uses GPIO36 for generated telephone tones, common ground, SPEK+ and MIC+.

Leave SPEK- insulated and floating.
Connect MIC- to system ground through the external 1 µF film or bipolar capacitor used in the tested build.

Prepared LilyGO audio and tone harness

The signal-only conductors in this harness are 28 AWG. Cut and prepare them as follows:

Connection	Color	Length	Preparation
Common ground	Black	14 cm	Leave loose for its LilyGO connection
GPIO36 tone	Blue	18 cm	Leave loose for its LilyGO connection
`SPEK+`	Red	10 cm	Installed in the two-position SPEK connector
`MIC+`	Red	10 cm	Installed in the two-position MIC connector
`SPEK-`	Black	—	Remove this conductor from the SPEK cable
`MIC-`	Black	Start with 10 cm	Leave long initially; cut to fit when soldering the capacitor and ground connection

Both audio connector branches begin as 10 cm cables. Removing the black SPEK- conductor leaves the speaker connector intentionally one-sided. The black MIC- conductor remains in its connector until the harness is installed, then is trimmed to the required route.

Installed SPEK and MIC connectors, common lead, tone lead and MIC reference capacitor

The close view shows the two audio connectors at the end of the controller and the reference capacitor fitted before the wiring is dressed into the carrier.

AG1171 control

The carrier logic harness uses GPIO15 for FR, GPIO16 for RM, GPIO37 for SHK, and GPIO21 for PD. Record the connector orientation before inserting the contacts into their housing.

Controller with the signal and reset harnesses attached

The connector remains outside the controller outline while its individual conductors follow the edge of the board. The 10 cm signal wires are long enough to reach the carrier without adding unnecessary slack.

Hardware reset

Connect GPIO35 to the A4 trigger input. The other two A4 reset conductors attach across the LilyGO physical power-switch path so the A4 board can remove and restore battery power. The installed close-up below shows the two switch points used for RAW_BAT and SW_BAT on the working assembly.

Prepared three-wire hardware-reset harness

For the reset harness shown above:

Wire	Length	Gauge	Purpose
Red	16 cm	24 AWG	Power-switch path
Yellow	16 cm	24 AWG	Power-switch path
Green	18 cm	28 AWG	Reset trigger signal

The extra 2 cm on the green trigger wire allows it to follow the required route without pulling against the two power-switch conductors.

Close view of the power-switch taps and lower GPIO connections

The red and yellow conductors start at the two switch points. The longer green trigger lead starts farther down the controller and joins them after following the board edge, which accounts for its additional 2 cm.

Charging

Bring regulated 5 V from the selected rear connector to the LilyGO charging input and system ground. Keep this charging input separate from the AG1171 carrier's battery supply.

Arrange and strain-relieve the new wiring so both USB ports and both QWIIC connectors remain accessible.

Dress the wiring into the carrier

Prepared LilyGO wiring routed through the printed carrier

This carrier view shows why the harnesses are not all cut to one length. The audio, reset and control conductors begin at different points on the LilyGO, follow the open channel through the carrier, and leave together near their destination boards. The shorter power and connector leads only need to clear the carrier edge.