Placement was inspected, but no project mutations were made.
Board: 21 × 10 mm, custom 4-layer, 1.60 mm thick.
Connector J9: top side at approximately (−2.8, +1.45) mm; footprint/courtyard is about 14.9 × 8.5 mm. This connector alone cannot fit a 10 × 8 mm board, so the current 21 × 10 mm outline cannot safely be reduced to the target without selecting a smaller connector.
Microphone MK1: bottom side at (+7.6, 0) mm. The enclosure inlet datum is therefore the centered through-board acoustic hole at (+7.6, 0) mm, currently 0.8 mm diameter.
Port direction: the INMP441 is a bottom-port microphone—its acoustic opening faces the PCB. The datasheet recommends an aligned PCB hole of 0.5–1.0 mm, so the present 0.8 mm hole is appropriate.
Decoupling: C11 is 100 nF, matching the datasheet requirement, but the datasheet requires it close to VDD with short, same-layer, via-free connections.
Physical blocker: the actual INMP441 package is 4.72 × 3.76 × 1.00 mm, while the current MK1 layout bounds appear only about 3.55 × 3.26 mm. Its SMD pads also appear fixed to Top copper while MK1 is placed on Bottom. The footprint therefore needs correction and re-verification before placement can be approved or C11 safely repositioned.
Checks: no overlap, bounds, keepout, edge, or neckdown placement errors were reported. Seven expected airwires remain; no routing was performed. A board-density warning remains.
The board is not ready for routing until the MK1 footprint/layer issue is corrected and the connector-versus-10 × 8 mm size conflict is resolved. The independent review completed, but I could not retrieve and reconcile its final report because execution stopped when your ACUs ran out.
Status: MP-R6 mechanical package and the four-PCB electrical architecture are confirmed. The schematic is partitioned with explicit paired board-to-wire interfaces and board ownership groups, ready to clone and prune into independent Main, Encoder, Finger, and Microphone board projects. PCB sizing, placement, and routing remain intentionally unstarted; battery peak-current qualification, RF testing, and fabrication approval remain open.
Project Overview
A compact wireless creative shortcut controller shaped as a near-circular left-hand stick grip. Four molded-silicone lobes form one continuous finger keypad under the curled fingers, while two vertically stacked dials sit on the adjacent thumb face. The palm-contact region remains smooth and supportive.
Intended Use
Handheld control surface for editing, illustration, CAD, streaming, music, and other creative software.
Production-intent architecture, developed first through ergonomic and functional prototypes before committing to molded tooling.
Indoor consumer-electronics environment.
What the Device Should Do
Pair with a computer over Bluetooth Low Energy.
Pair with a computer using Bluetooth Classic Hands-Free Profile for live microphone audio and Bluetooth HID for programmable controls.
Send configurable keyboard shortcuts and rotary control actions.
Support four independent silicone buttons.
Support two rotary encoders, each with a push-click function.
Capture voice or ambient audio through a built-in microphone at the top end.
Store and recall user mappings.
Recharge through USB-C.
Enter a low-power sleep state and wake from user interaction.
Main Features
Rounded cylindrical handheld stick enclosure curved to the natural left-hand grip.
Four finger-following controls with both dials vertically aligned along the thumb side.
Four production-grade compression-molded silicone buttons.
Two rotary dials positioned for thumb/index-finger access.
Bluetooth wireless connection.
Broad-compatibility Bluetooth headset audio using speech-oriented CVSD/mSBC, with no dedicated USB receiver.
Rechargeable internal lithium battery.
USB-C charging port.
Subtle status indication without a display.
Flush top-mounted microphone acoustic inlet opposite the bottom charging port.
System Architecture
Diagram
Hardware Subsystems
Compute and radio: First proof-of-concept uses a dual-mode ESP32 platform supporting Bluetooth Classic HFP plus HID. This validates host behavior and ergonomics; a lower-power production audio SoC may replace it after testing.
Buttons: Four PCB contact locations actuated by a single molded silicone keypad; final contact technology to be selected during engineering validation.
Rotary controls: Two detented incremental encoders with integrated push switches and custom knobs.
Audio input: Board-mounted top-position-constrained INMP441 I2S MEMS microphone with a protected acoustic port; acoustic mesh and enclosure treatment remain open.
Power: Single-cell rechargeable lithium battery, USB-C charging, battery protection, regulated system rail, and physical power control.
Programming/debug: Production programming and test interface accessible during assembly.
Confirmed Four-Board Electrical Partition
MAIN — 30 × 115 mm: ESP32-WROOM-32E, USB-C input and protection, BQ24074 charger/power path, TPS63031 3V3 regulator, battery connector, physical power control, programming/debug, status LED, and the main-side daughterboard connectors.
ENCODER — 18 × 48 mm: U4/U5 clickable encoders, their six local 10 kΩ inactive-high bias resistors, and the encoder-side harness connector.
FINGER — 8 × 68 mm: SW1–SW4, their four local 10 kΩ inactive-high bias resistors, and the finger-side harness connector.
MIC — 10 × 8 mm: Bare bottom-port INMP441 LGA microphone, local 100 nF VDD decoupling, local 100 kΩ SD discharge pull-down, and the microphone-side harness connector.
All four boards use 1.6 mm Standard 4 Layer, through vias, 1 oz copper. This specification records the stackup intent only; no PCB outline, placement, or routing was performed in this phase.
Daughterboard connector pinouts
All links use polarized JST PH, 2.0 mm pitch, SMT board headers on both PCB ends with detachable wire harnesses. Paired ends use the same pin number and net.
The finger link carries both GND and 3V3 because the existing active-low topology keeps the four 10 kΩ pull-ups local to the finger control block; each switch closes its signal to GND. GPIO assignments and existing signal net names are unchanged.
Interfaces and Connections
Bluetooth Classic HFP to the host computer for speech-quality microphone audio.
Bluetooth HID to the same host for programmable keys and dial actions.
USB-C used for charging; wired data is not required in the initial product definition.
Four button inputs and two encoder quadrature pairs plus two encoder push inputs.
Digital microphone interface to the controller.
Explicit detachable JST PH harnesses connect the Main PCB to the Encoder, Finger, and Microphone PCBs using the documented one-to-one pinouts above.
One status indicator visible through or around the enclosure.
Power and Runtime Expectations
Rechargeable single-cell LiPo battery.
Proof-of-concept target: at least 8 hours of active microphone use or multiple days of intermittent control use per charge; final production runtime will be set after measured prototype current.
Automatic sleep after inactivity and wake from button or dial interaction.
Charging should be safe while the device remains operational.
Power Tree and Power Budget
The proof-of-concept selects ESP32-WROOM-32E, INMP441, BQ24074 power-path charging, and TPS63031 fixed3.3 V regulation. The electrical sizing basis remains in Power Budget. MP-R3 supersedes MP-R1/R2's30 ×50 ×6 mm battery with a provisional protected20 ×62 ×5 mm,600 mAh THOR-502060 packaging candidate and22 ×66 ×7 mm installation reserve. Manufacturer protected dimensions are approximate; final drawing, swelling/lead/NTC/polarity qualification remains open. Its stated600 mA continuous discharge does not establish compatibility with the existing766 mA peak: obtain a qualified pulse rating/higher-rate pack or reduce peak demand before powering hardware. At188 mA/3.3 V, assumed85% conversion and80% usable capacity, continuous audio runtime estimates2.43 hours, not the8-hour aspiration; see Mechanical Package for the full tradeoff. No electrical values or components were changed.
Table
Load
Mode
Provisional expectation
BLE controller
Sleep
single-digit to tens of µA
BLE controller
Connected idle
sub-mA average target
ESP32 compute/radio
HFP + HID active
180 mA planning value
ESP32 compute/radio
Radio/transient design peak
500 mA
Digital microphone
Streaming
2.2 mA typical at 3.3 V
Status indicator
Active
1 mA maximum, duty limited
Encoder/buttons
Static
near-zero except pull networks
3V3 rail design total is approximately 188 mA typical and 522.5 mA peak. At 3.0 V battery input and approximately 75% conversion efficiency near full load, estimated peak battery current is about 766 mA. The present power-only USB-C implementation uses the BQ24074 fixed USB500 500 mA input limit because it does not measure Type-C advertised current; provisional charge-current programming remains 500 mA, with system load priority reducing charge current as needed.
Manufacturing and Assembly Expectations
Final housing intended for molded production, with prototype housings made additively or by low-volume processes first.
Silicone keypad intended for compression molding with a dedicated tool after tactile geometry is validated using prototype molds.
PCB intended for automated SMT assembly.
Include production test points for power, programming, buttons, encoders, charging, and radio bring-up.
Design must support practical assembly, battery replacement during service, and consistent keypad compression.
Firmware-Relevant Hardware Requirements
Bluetooth HID keyboard/consumer-control behavior.
Bluetooth HFP Hands-Free Unit behavior with mSBC wideband speech when supported by the host and CVSD fallback.
One finger button may be mapped to push-to-talk; host or firmware logic may also provide voice-trigger behavior.
User-remappable actions and profiles.
Rotary acceleration and configurable direction.
Debounce for silicone buttons and encoder switches.
Persistent configuration storage.
Battery-level reporting and low-battery behavior.
Sleep/wake management and a recoverable pairing/reset method.
Firmware update path through debug pads or USB during production/service.
Audio capture, microphone power control, and optional mute behavior; the host audio profile and recording use case remain open.
Audio is streamed live to the computer rather than stored locally.
Physical Design Expectations
Ergonomic source of truth: preserve the user-supplied hand-held concept image. The hand wraps naturally around a slim cylindrical body; the two dials are under the thumb, and the four buttons align individually with the curled index, middle, ring, and little fingers. Controls must wrap around adjacent faces of the cylinder rather than being forced into one flat/shared face.
The thumb-dial and finger-button regions may both be visible in an oblique view, but they are functionally distinct surfaces separated by the body's curvature. This decision overrides the MP-R3/MP-R4 shared-control-face arrangement.
Current approved MP-R6 package uses the confirmed board envelopes: main 30 × 115 × 1.6 mm, encoder 18 × 48 × 1.6 mm, finger 8 × 68 × 1.6 mm, and microphone 10 × 8 × 1.6 mm. Mechanical Package holds the checked mechanical assets and fit evidence. No PCB outline or placement was changed in this schematic-partition phase.
Upright rounded cylindrical stick silhouette with finger-side curvature and a secure palm-side body.
Four broad silicone buttons aligned to the curled left index, middle, ring, and little fingers.
Two rotary dials stacked vertically on the left-thumb side, reachable without releasing the stick grip.
USB-C charging at the bottom end, mating axially; physical power actuator provisionally on the lower thumb face.
Comfortable handheld grip with no sharp seams or pressure points.
No display.
Microphone acoustic port at(0,−10,152), offset10 mm toward the clean palm side, opposite axial bottom USB-C at(0,1.35,0.5). Short top acoustic path and bottom-port mic satellite remain provisional; exact port offset awaits corrected footprint.
Antenna region must remain clear of battery, large metal controls, and internal shielding.
MP-R3 antenna-to-housing minimum is8.838 mm, not the literal15 mm recommendation. Battery/finger PCB/mic PCB distances are35.185/21.198/20.769 mm; mic flex15.600 mm and upper encoder28.150 mm. Plastic-head loading, host-board copper keepout and in-hand RF performance require validation; no conductive finish/filler or metal fasteners near the head. This slim-head compromise needs approval.
MK1 now uses a project-local, datasheet-backed bare INMP441 nine-terminal LGA component with the central bottom-port acoustic opening; the known-invalid through-hole header footprint was removed. U1 is consistently identified as ESP32-WROOM-32E, and its PCB-antenna edge must face outward into a host-board copper/component keepout. The module is 18.0 × 25.5 × 3.1 mm and the short antenna edge is the keepout edge.
Important Design Decisions
Wireless-first Bluetooth product rather than a wired macro pad.
Four soft silicone buttons rather than mechanical key switches.
Two clickable rotary encoders.
Production-molded construction is the end goal, but tooling is deferred until ergonomic, tactile, and electronic prototypes are validated.
Assumptions
The first product version is shaped specifically for the left hand; a right-hand version would be a mirrored mechanical variant.
Indoor use only; no ingress-protection rating is targeted initially.
A companion configuration utility may be developed later; initial mapping can be firmware-defined.
Final materials, colors, battery capacity, keypad durometer, legends, and contact technology remain open pending concept and prototype testing.
Change Notes
Confirmed and captured the MP-R6 four-board architecture. Added paired 8-pin encoder, 6-pin finger, and 5-pin microphone JST PH interfaces without changing GPIO assignments; assigned every schematic component to MAIN, ENCODER, FINGER, or MIC ownership groups; replaced the invalid MK1 module footprint with a bare INMP441 LGA part; and reconciled U1 metadata to ESP32-WROOM-32E.
Adopted the user-supplied hand-held concept image as the ergonomic source of truth. Future mechanical work must return the two vertical dials to the thumb face and the four silicone buttons to the adjacent curled-finger face; the one-face MP-R3/MP-R4 control arrangement is superseded. Top microphone and bottom axial USB-C remain unchanged.
MP-R3 user-directed slimming and immediate shared-face adjustment:42.4 ×43.4 ×152 mm housing; six controls in two adjacent columns, one continuous silicone web, clean palm, narrower600 mAh protected-pack allocation and repackaged boards. Matching checked closed/open geometry and five inspected views are in Mechanical Package. Native checks found and repaired gasket interference. Battery current qualification,2.43-hour estimated audio runtime versus8-hour aspiration, tight mic-flex clearance and8.838 mm antenna-shell spacing are disclosed; stop at visual approval with PCB unchanged.
Revised industrial-design direction to an upright left-hand stick grip, with the hand wrapped around the body, four finger buttons, and two vertically stacked thumb dials.
Added a built-in top microphone opposite the bottom USB-C charging port.
Selected broad-compatibility Bluetooth Classic headset audio; the first electronics proof-of-concept will use dual-mode ESP32 HFP plus HID.
Added provisional MP-R1 mechanical package with matching closed, exploded and left-hand pose CAD-derived assets. Placeholder 160 × 100 mm board and its placement were inspected but deliberately not used as the shell driver or modified. Visual approval, exact pack selection and ergonomic/RF tests remain open.
Added user-directed MP-R2 actual geometry revision with matching closed/open CAD assets; MP-R1 exterior is superseded/rejected, not approved. Preserved144 mm length,26 mm dial pitch,18 mm key pitch and core electrical envelopes. Removed exposed screw-head arrays; concealed/recessed service closure remains unengineered. Screening found likely carrier and upper wire-corridor interference plus visible cap-side gaps; no fabrication acceptance or further detailed CAD is authorized. MP-R1 battery, top-port and plastic-head RF proposals remain provisional where retained by MP-R2.