Iris cortex

Iris Cortex

The head controller of Iris: an ESP32-S3 (16 MB flash, 8 MB PSRAM) with the eye camera's FPC, the iris-ring LED drivers and the harness to the brainstem and brow. It rides the tilt cradle.

Part of Iris, the human-eyed robot head, HeyPCB's open robot boards. Designed end to end with the HeyPCB method on KiCad 10 (headless pipeline, Freerouting 2.4.1); every number below is measured on the files in this repository. Mentions of ./run.sh, docs/rules/, blocks/ or parts/ refer to the heypcb-kicad SDK that produced them.

Not fabricated, assembled or powered.

Iris Cortex is the head controller of Iris, an open-hardware robot head with human-like eyes. It is board B1 of the Iris design spec (v0.1, 2026-10-03, section 4.1; not published, its binding contracts are in the Iris system docs). An ESP32-S3-WROOM-1-N16R8 runs the OV2640 camera in the right eye through a 24-pin FPC connector. Two buffered outputs drive the WS2812C iris LED rings. Five JST SH headers carry the spec's binding harness contracts to the Brainstem (B2), the Brow strip (B4) and the two iris rings (B3). The design was made with the HeyPCB method on KiCad 10 (10.0.6), using heypcb-kicad's headless pipeline and Freerouting 2.4.1. The input is the brief in board.json.

This board has not been fabricated, assembled or powered, and its firmware has not been written. Every number below comes from KiCad and the pipeline, measured on the design files (report.json of the final run, 2026-10-03). Nothing here has been tested on hardware.

Where it sits in Iris

• It rides the tilt cradle. B1 is screwed to four Ø5 bosses with M2 heat-set inserts on the cradle's rear plate (spec part P5). It tilts with the eyes, so the camera FPC only has to flex for pan (one out-of-plane bend). The B1-B2 harnesses take the ±30° tilt as a bend near the axis.
• Frame. In the head frame H at tilt 0 (origin between the eye centres, +X forward out of the face, +Y robot-left, +Z up), the F face is at X = -52.0 and faces the eyes. The B face is at X = -53.6 and rests on the bosses. Board coordinates map as Y = x - 40 and Z = 20 - y. Board coordinates are mm from the outline's top-left corner, with x to the right and y down, seen from F.
• Neighbours.
  • The OV2640 module sits in the right eye at Y -39. Its FPC exits temporally (toward -Y), bends back along -X, then runs +Y along B1's F face into J1.
  • B2 (the Brainstem) sits below, at Z -60. H1 and H2 leave B1's bottom edge toward it.
  • B4 (the Brow) sits above, at Z +50. BROW leaves upward.
  • The two iris rings (B3) are inside the eyes, at Y ±39.
• v1 scope. Iris v1 has a fixed head (no neck), one camera (mono vision) and a stylised hard-shell face. B1 follows the spec's design for that scope.

Features

• ESP32-S3-WROOM-1-N16R8 (U1, LCSC C2913202): 16 MB flash, 8 MB octal PSRAM, Wi-Fi and BLE. It sits on the B face, centred, with its antenna end at the top edge. Native USB 2.0 FS runs over H1 from B2's USB-C data port; there is no USB-serial bridge.
• Camera.
  • J1 is a Jushuo AFC07-S24FCA-00: 24 pins at 0.5 mm, bottom contact, slide lock.
  • The camera pins use the ESP32-S3-EYE map, so esp-who and esp32-camera board configs apply unchanged.
  • SCCB has 4.7 k pull-ups to DOVDD. RESETB has 10 k to DOVDD and 100 nF to GND. PWDN has a 10 k pull-down and also goes to GPIO46.
  • PCLK, VSYNC and HREF pass through 0 ohm links. They can be swapped for 33-100 ohm.
  • AVDD, DOVDD and DVDD each have 4.7 uF + 100 nF at the connector.
• Camera supplies. U3 (ME6211C28) makes 2.8 V for AVDD + DOVDD. U4 (ME6211C12) makes 1.2 V for the OV2640 core. For an OV3660 or OV5640 module, fit ME6211C15 (C53100) in U4's place: same footprint, same pins.
• Iris ring drivers.
  • Two SN74AHCT1G125 buffers (U5, U6) turn the RMT outputs on GPIO47 / GPIO48 into 5 V WS2812 data. Each buffer has a 33 ohm series resistor, and a 100 k pull-down that keeps its input low through reset.
  • Each ring is fed from 5V_SYS through its own 0.5 A resettable fuse (F1, F2), with 10 uF behind it.
• Harness headers (JST SH side entry, pinouts below): J5 H1 (SH-10), J6 H2 (SH-7), J4 BROW (SH-8), J2 RING_R and J3 RING_L (SH-4). Every SH header on the board has a different pin count, except the two interchangeable ring headers.
• 3V3 from a TLV62569 buck (U2): 2 A part, 2.2 uH, 3.327 V by its 100 k / 22 k divider.
• System I2C bus master. The bus's only pull-ups (2.2 k) are on B1. nINT (the INA226 ALERT on B2) has a 10 k pull-up here.
• I2S, full duplex. BCLK and WS go to both B2 (amplifier) and B4 (microphones), each branch through its own 33 ohm source resistor. The amplifier data goes out and the microphone data comes in (100 k pull-down).
• Bring-up.
  • BOOT (SW1) and RESET (SW2) buttons are on the B face.
  • Nine 1.0 mm test pads on the F face: 3V3, 5V, GND, TX, RX, SDA, SCL, PCLK and U0TX (the ESP32-S3's ROM boot log).
• Board.
  • 80.0 x 40.0 mm with 2.0 mm fillets, 1.6 mm, 4 copper layers.
  • Layers: F.Cu signal / In1 GND plane / In2 signal with a 3V3 pour / B.Cu signal. F.Cu and B.Cu have GND pours.
  • Four M2 holes.
  • Double-sided assembly: 32 parts on F, 32 on B.

Block diagram

flowchart LR
    B2["B2 Brainstem"]
    B4["B4 Brow"]
    CAM["OV2640 module, right eye"]
    RR["B3 iris ring, right"]
    RL["B3 iris ring, left"]
    subgraph B1["B1 Iris Cortex, 80 x 40 mm, 4 layers"]
        J5["J5 H1, SH-10"]
        J6["J6 H2, SH-7"]
        J4["J4 BROW, SH-8"]
        J1["J1 FPC, AFC07 24P"]
        J2["J2 RING_R, SH-4"]
        J3["J3 RING_L, SH-4"]
        U1["U1 ESP32-S3-WROOM-1-N16R8, B face"]
        U2["U2 TLV62569 buck"]
        U3["U3 ME6211C28, 2V8"]
        U4["U4 ME6211C12, 1.2 V"]
        U5["U5 74AHCT1G125"]
        U6["U6 74AHCT1G125"]
        F1["F1 PTC 0.5 A"]
        F2["F2 PTC 0.5 A"]
        J5 -->|"5V_SYS"| U2
        J5 -->|"5V_SYS"| F1
        J5 -->|"5V_SYS"| F2

Outline, holes and connectors as built

Measured on the final board file (kicad/iris_cortex.kicad_pcb).

• Outline: 80.0 x 40.0 mm rectangle. Edge.Cuts fillets are r 2.0 mm, centred at (2, 2), (78, 2), (2, 38) and (78, 38). The board is 1.6 mm thick (gerber job).
• Holes: four Ø2.2 mm NPTH (MountingHole_2.2mm_M2) for M2 x 6 screws into the cradle's heat-set inserts.

The bosses' faces are at X = -53.6 (the B face).

Connectors. All six connectors are on the F face, so their bodies stand from X = -52.0 toward the eyes. The AFC07 is 2 mm tall (catalogue row C262567). For the SH housings, LCSC lists 2.9 mm and 4.32 mm body dimensions; the spec's F-face budget is 4.5 mm.

• "Body" is the footprint's fabrication outline.
• The SH pin rows run along the body's long side. On J2, J5 and J6, pin 1 is the leftmost pin (lowest x). On J4 (turned 180°), pin 1 is the rightmost. On J3, pin 1 is the lowest. On J1, pin 1 is at the top and pin 24 at y 25.75.
• On the B face:
  • U1, the ESP32-S3 module: fab outline x 30.95-49.05, y 0.50-26.10 (head Y -9.05 to +9.05, Z -6.10 to +19.50). Its antenna is at the top. Keep the cradle's rear plate free of metal and cables over the antenna.
  • SW2 RESET at (58.6, 10.5) and SW1 BOOT at (58.6, 17.5), each 5.1 x 5.1 x 1.5 mm.
  • Everything on B is at most 3.1 mm tall, inside the spec's 3.6 mm.

Connector pinouts

The pin tables below are copied exactly from the Iris spec, section 5 (binding). "Pin n" is pad n of the KiCad footprint named. All SH cables are double-ended, same direction (pin n to pin n), 28 AWG and pre-crimped. The B1 net names follow each table. They were checked pad by pad on the final board.

H1: B2 J5 ↔ B1 J5 (SH-10).

On B1, J5 pins 1-10 carry 5V_SYS, 5V_SYS, GND, GND, USB_DN, USB_DP, GND, BUS_TX, BUS_RX, SERVO_EN, with 22 uF + 100 nF on 5V_SYS at the connector. (U3, U5, U7, U8 and Q1 in the Notes column are B2's parts.)

H2: B2 J6 ↔ B1 J6 (SH-7).

On B1, pins 5 and 6 are the nets I2S_BCLK_AMP and I2S_WS_AMP, after R21 and R22 (33 ohm). R18 and R19 (2.2 k) and R20 (10 k) are the pull-ups.

BROW: B1 J4 ↔ B4 J1 (SH-8).

On B1, pins 5 and 6 are I2S_BCLK_MIC and I2S_WS_MIC, after R15 and R16 (33 ohm). R17 (100 k) is the I2S_MIC_SD pull-down. The connector has 1 uF + 100 nF on 3V3.

RING_x: B1 J2 (right) / J3 (left) ↔ B3 pads (SH-4 to wires).

On B1, pin 1 is 5V_LED_R (J2, behind F1) or 5V_LED_L (J3, behind F2): one 0.5 A PTC per ring. Pin 2 is RING_R_DATA or RING_L_DATA, the buffer's output through 33 ohm (R11, R13).

CAM: module ↔ B1 J1 (24P FPC; pad n = module pin n, §3.2).

On B1, these are the net names:

• pin 3 CAM_SIOD and pin 5 CAM_SIOC;
• pin 6 CAM_RESET and pin 8 CAM_PWDN;
• pins 7, 9 and 17 are CAM_VSYNC_J, CAM_HREF_J and CAM_PCLK_J, ahead of the 0 ohm links R9, R10 and R8;
• pin 10 CAM_DVDD (1.2 V as fitted);
• pins 4 and 11 2V8;
• the data pins CAM_D0-CAM_D7 and CAM_XCLK;
• pins 1, 23 and 24 unconnected.

ESP32-S3 GPIO map

The binding allocation is Iris spec 4.1. The camera lines match the ESP32-S3-EYE (espressif/esp-bsp esp32_s3_eye.h). Module pin numbers are those of the KiCad 10 symbol RF_Module:ESP32-S3-WROOM-1.

Power rails

Copper:

• The net classes are SYS5V 0.5 mm (5V_SYS), PWR3V3 0.4 mm (3V3), LED5V 0.4 mm (5V_LED_R / L) and BUCK 0.5 mm (U2_SW). Each has a currentA, so the routing ladder never narrowed them; on this run it did not need to narrow anything (classes_routed is empty).
• After routing, In2 is poured 3V3 and In1 is a solid GND plane.

Measured gates

Final run: ./run.sh --board boards/iris_cortex, 2026-10-03, KiCad 10.0.6, Freerouting 2.4.1. The numbers are read from report.json.

Timing: the final full run took 4 min 6 s. The route stage took 57.5 s, the renders 154.7 s and the video 20.1 s.

The same brief routed identically in its last --no-media run before the full run: 913 tracks, 101 vias, 2221.3 mm, DRC 0 / 0 / 0, 0 warnings.

Departures from the spec, and why

1. J4 (BROW) is 7.6 mm below the top edge, at x 11.95-22.05. The spec zone was x 16-28 at the top edge.

   • KiCad's RF_Module:ESP32-S3-WROOM-1 footprint carries Espressif's antenna keep-out: 15 mm beyond each side of the module, on every copper layer, banning footprints, pads, tracks, vias and pours. With the module centred, that covers x 16-64, y 0-6.55. No header fits at the top edge between it and the H1 hole.
   • J4 still opens upward, toward B4. Its plug rests over bare laminate in that strip.
   • The mechanism CAD should route the BROW cable up from Z +12.4 over the board face.
   • The spec's own antenna keep-out (x 31-49, y 0-7) is also in the brief, as a tracks / vias / pour ban.

2. The module sits 0.5 mm inside the top edge (its outline spans y 0.50-26.10), not flush.

3. One PTC per ring. The 5V_LED pin is fed through its own 0.5 A PTC per ring, so the B1 nets are 5V_LED_R and 5V_LED_L. A short in one eye's wires then leaves the other eye lit. The pinout is unchanged.

4. Additions the spec does not list:

   • 100 k pull-downs on both buffer inputs, because GPIO47 / GPIO48 float through reset;
   • 33 ohm source resistors on the ring data lines;
   • 10 uF on each 5V_LED;
   • 22 uF + 100 nF on 5V_SYS at J5;
   • 1 uF + 100 nF on 3V3 at J4;
   • 1 uF in and out at each ME6211, per Microne's typical application.

   The buffers run from 5V_SYS ahead of the PTCs, so a PTC's drop cannot take them below their 4.5 V minimum.

5. Test pads are on the F face, in a 3 x 3 grid right of the module's position. Each pad's name is printed beside it. A first layout with a column on B, among the camera lines' vias, left 7 of 9 names unplaced.

6. SDK notes (not changes):

   • The spec's board fragment spells the keep-out ban "pours". The SDK's word is "pour"; the brief uses "pour", and "pours" would be refused as bad_keepout.
   • The fragment's footprints ban over x 31-49, y 0-7 would flag the module itself, so the brief leaves it to the footprint's own rule area.
   • The placer's top-edge anchor rung only places at rot 0. KiCad flips a bottom-side part top-to-bottom, so the module is locked at rot 180 instead.
   • The placer reads the module's courtyard as its bounding box (x 16-64 with the keep-out). Its thermal-via pads also make it count as through-hole. So the module's B-face neighbours are locked by hand.

Assembly notes

• Double-sided SMT. The B face carries:

  • U1, U3 and U4;
  • BOOT and RESET;
  • the module's bypass and EN parts;
  • the FPC's pull-ups, links and decoupling;
  • the five I2S / MIC_SD resistors next to the module.

  The F face carries the connectors, the buck, the ring drivers and the test pads. Check JLC's placement preview for the bottom side, especially pin 1 of U1 (top right when seen from F).

• Camera FPC orientation.

  • J1 opens to the board's left edge (head -Y), on the F face.
  • The OV2640 module's FPC comes back from the right eye, bends about Z near B1, and runs +Y along the F face into J1.
  • The AFC07 is bottom contact, so insert the FPC with its gold fingers facing the board. Open the slide lock first and close it after full insertion.
  • Module pin n lands on pad n. Pad 1 is at the top of J1 (y 14.25, head Z +5.75); pad 24 is at the bottom.

• First power-up check for the camera. With the module inserted, J1 pads 2 (AGND) and 15 (DGND) must read 0 ohm to GND. If they do not, the FPC is reversed or the module uses the AI-Thinker ESP32-CAM numbering: map by signal, never by number.

• FPC length. Buy the 120 mm class. The spec budgets about 72 mm plus pan slack, and the 75 mm module is too short.

• Image orientation.

  • Whether the sensor rows run along the FPC exit edge is open question Q2 in the spec. If they do, correct the image with the OV2640's vflip / hmirror.
  • If not, rotate the image in firmware. Verify at first light.

• DVDD. U4 is fitted for an OV2640 (1.2 V). For an OV3660 / OV5640 module, replace U4 with ME6211C15M5G-N (C53100) before inserting that module.

• Rings. Each ring cable is SH-4 at B1 and four 32 AWG wires soldered to B3 pads P1-P4 (5V_LED, LED_DIN, GND, GND). J2 is the right eye, J3 the left. The two are interchangeable, and firmware has a swap flag.

Check before ordering

1. Re-check stock and class at jlcpcb.com. The pinned rows are live lookups from 2026-10-03. The lowest stocks are SM04B-SRSS-TB (C160404) at 7,284 and ME6211C28 (C53099) at 15,900.

2. Buy the camera module first. Confirm its 24-pin pinout against the CAM table, its contact side and its FPC length (≥ 100 mm overall). Then decide U4's voltage.

3. Confirm with the mechanism CAD:

   • the connector positions in the table above, especially J4's lowered position and the BROW cable path;
   • the J1 entry from the left edge;
   • the B-face heights (U1 3.1 mm, buttons 1.5 mm) against the cradle bosses.

4. Keep the antenna clear. Nothing conductive on the cradle's rear plate over x 16-64, y 0-7 (head Y -24 to +24, Z +13 to +20). The BROW plug and cable pass at the left end of that strip; check RSSI on the first board.

5. Stackup. The board file carries KiCad's derived 4-layer stackup (gerber job: 1.6 mm, 0.48 mm dielectrics). JLC's real stackup is chosen when ordering. USB and DVP are not impedance-controlled: USB FS and a 20 MHz DVP clock do not need it over these lengths.

6. USB ESD sits on B2 (U5 there), not here. A cable plugged straight into H1 from anything but B2 has no protection.

7. Footprint polarity and orientation in the JLC preview:

   • U1 pin 1 (on B);
   • the SOT-23-5 parts;
   • the SH headers' pin 1 marks.

   The CPL was rotation-corrected for 28 parts.

8. Firmware facts the hardware assumes (spec section 8; not written yet):

   • GPIO46 must stay low at reset (R7 holds it);
   • write the VL53L1X to its 2V8 I/O mode;
   • RMT on GPIO47 / GPIO48 at 800 kHz with a 30 % brightness cap on USB-only power;
   • SERVO_EN stays low until the INA226 reads VIN ≥ 8.5 V.

9. No 3D body for J1. KiCad 10.0.6 ships no model for the Jushuo AFC07 footprint, so J1 shows as bare pads in the renders and has no body in the STEP. Use the catalogue drawing for the 2 mm-tall housing.

Sources

Facts and URLs only; no datasheet files are stored in this repository.

• Iris design spec v0.1 (not published; binding contracts in the Iris system docs): sections 0, 2.8, 3, 4.1, 4.5, 5, 6 and 8. The outline and holes come from its board-outline script and are in board.json.
• ESP32-S3-EYE camera pin map:
  • espressif/esp-bsp, bsp/esp32_s3_eye/include/bsp/esp32_s3_eye.h (camera GPIOs), https://github.com/espressif/esp-bsp/tree/master/bsp/esp32_s3_eye;
  • the ESP32-S3-EYE-MB v2.2 schematic, https://dl.espressif.com/dl/schematics/SCH_ESP32-S3-EYE-MB_20211201_V2.2.pdf.
• Espressif documents:
  • ESP32-S3-WROOM-1 datasheet (supply ≥ 0.5 A, TX peak 355 mA, IO35-37 to the octal PSRAM, antenna keep-out), https://www.espressif.com/sites/default/files/documentation/esp32-s3-wroom-1_wroom-1u_datasheet_en.pdf;
  • ESP32-S3 datasheet (DVP up to 40 MHz), https://www.espressif.com/sites/default/files/documentation/esp32-s3_datasheet_en.pdf.
• Camera:
  • OmniVision OV2640 datasheet (DVDD 1.14-1.26 V; supply currents), https://www.uctronics.com/download/cam_module/OV2640DS.pdf;
  • Union Image / Seeed OV2640 module drawing, https://files.seeedstudio.com/wiki/SeeedStudio-XIAO-ESP32S3/res/OV2640-datasheet.pdf;
  • esp32-camera issue #439 (series resistor on HSYNC), https://github.com/espressif/esp32-camera/issues/439.
• Power and logic parts:
  • TI TLV62569 datasheet SLVSDG1C (VFB 0.6 V, R2 ≤ 200 k, 2.2 uH + 10 uF standard filter, 10-47 uF out, 4.7 uF in, EN must not float), https://www.ti.com/lit/ds/symlink/tlv62569.pdf;
  • Microne ME6211 datasheet (1 uF in, 1 uF out, CE enable), https://stm32-base.org/assets/pdf/regulators/ME6211.pdf;
  • TI SN74AHCT1G125 datasheet, https://www.ti.com/lit/ds/symlink/sn74ahct1g125.pdf;
  • Sunlord SWPA4030S series specification (2.2 uH: Isat 4.90 A, Irms 2.95 A minimum), https://www.alfatec.de/fileadmin/productfiles/datasheets/sunlord_swpa4030s_series.pdf.
• Part numbers, stock, class and the catalogue facts quoted (PTC resistance, SH and AFC07 heights, buffer supply range) come from live JLC/LCSC lookups through jlcsearch.tscircuit.com on 2026-10-03. They are pinned in parts/lcsc_pinned.json with that date.
• Pins come from the installed KiCad 10 symbols. Footprints and 3D models are KiCad's stock libraries.

Licence

SPDX-License-Identifier: CERN-OHL-S-2.0

Copyright 2026 enkhbold470.

This source describes Open Hardware and is licensed under the CERN-OHL-S v2. You may redistribute and modify this source and make products using it under the terms of the CERN-OHL-S v2 (https://ohwr.org/cern_ohl_s_v2.txt). This source is distributed WITHOUT ANY EXPRESS OR IMPLIED WARRANTY, INCLUDING OF MERCHANTABILITY, SATISFACTORY QUALITY AND FITNESS FOR A PARTICULAR PURPOSE. Please see the CERN-OHL-S v2 for applicable conditions.

Source location: boards/iris_cortex/ in the heypcb-kicad repository, with the cortex_* blocks in blocks/.

The licence covers this board's brief, its cortex_* blocks and the files the pipeline builds from them. KiCad's symbols, footprints and 3D models are CC-BY-SA-4.0 with the KiCad library exception. The TS-1187A body in the renders is heypcb-kicad's generated envelope.

Files

• board.json is the brief everything is built from.
• img/ holds three raytraced renders from the final run: the F face, the B face and an isometric view.
• The blocks, in blocks/:
  • cortex_esp32s3, cortex_buck_tlv62569, cortex_ldo_me6211c28, cortex_ldo_me6211c12;
  • cortex_cam_fpc, cortex_ring_driver;
  • cortex_link_h1, cortex_link_h2, cortex_link_brow;
  • cortex_test_pads, cortex_mount_holes.
• Built by the pipeline (not committed; build/ is regenerated):
  • report.json;
  • kicad/iris_cortex.kicad_{sch,pcb,pro};
  • fab/: the gerber zip, the BOM (26 lines), the JLC CPL, positions, the schematic PDF and the STEP;
  • build/iris_cortex/render/;
  • media/design-process.mp4.

Reproduce

From the heypcb-kicad repository:

./run.sh --board boards/iris_cortex --no-media   # every gate
./run.sh --board boards/iris_cortex              # plus the 3D renders and the design-process video