09 — Bill of Materials (indicative)
Prices are indicative (USD, mid-2026) for the USB/HDMI bench prototype; verify before buying. This is not a costed BOM for the selected FPGA hardware target. “Qty” is for one instrument unless noted otherwise.
1. Core
Section titled “1. Core”| Item | Qty | ≈ Unit | Notes |
|---|---|---|---|
| ASRock N100DC-ITX board | 1 | $130 | Fanless, 19 V DC-in.1 |
| DDR4 SO-DIMM 16 GB | 1 | $35 | Single stick. |
| NVMe SSD (M.2 2280, 256 GB) | 1 | $30 | Immutable OS + data partition. |
| 19 V / 90 W DC brick | 1 | $25 | Headroom for fader inrush. |
| Donor instrument: Yamaha S90 | 1 | (owned) | Keybed + chassis. |
2. Audio
Section titled “2. Audio”| Item | Qty | ≈ Unit | Notes |
|---|---|---|---|
| RME Babyface Pro FS (bench baseline) | 1 | $749 | USB, class-compliant, balanced XLR out.2 |
| — or MOTU M4 (budget) | 1 | $280 | 4× balanced TRS, class-compliant.3 |
| — or RME HDSPe AIO Pro (PCIe) | 1 | $800 | Lowest latency; needs snd-hdspe + XLR breakout.4 |
| Panel-mount XLR/TRS connectors | 2–4 | $5 | Rear balanced outs. |
3. Microcontrollers & control surface
Section titled “3. Microcontrollers & control surface”| Item | Qty | ≈ Unit | Notes |
|---|---|---|---|
| RP2350 board (Pico 2, A3/A4) — keybed scanner | 1 | $5 | USB-MIDI scanner.5 |
| RP2350 board — control nodes | 2–4 | $5 | One per control cluster. |
| MCP2221A USB→I²C breakout | 1 | $7 | Host I²C bridge (/dev/i2c-N).6 |
| Analog mux (74HC4067) | per node | $1 | Fan out ADC to many pots. |
| H-bridge (DRV8833/TB6612) | per fader | $2 | Motor-fader drive. |
| Motor-faders (100 mm, motorised) | as needed | $15–25 | Position pot + motor (+touch). |
| Rotary pots / encoders | as needed | $1–3 | Knobs. |
| Tactile buttons / switches | as needed | $0.20 | Panel buttons. |
| LEDs / WS2812 strips | as needed | $0.10–0.50 | Indicators. |
| I²C bus buffer (PCA9517/P82B96) | 0–1 | $1.50 | Only for long/loaded bus runs.7 |
| Pull-up resistors, series R, ESD diodes | — | — | Bus + keybed protection. |
4. Display & UI
Section titled “4. Display & UI”| Item | Qty | ≈ Unit | Notes |
|---|---|---|---|
| Waveshare 7″ or 10.1″ HDMI capacitive panel | 1 | $70–95 | HDMI + USB-HID touch.8 |
| Short HDMI + USB cabling | 1 | $10 | Internal runs. |
5. Power & integration
Section titled “5. Power & integration”| Item | Qty | ≈ Unit | Notes |
|---|---|---|---|
| 5 V buck converter (≥ 3 A) | 1 | $6 | Panel/hub/faders. |
| 3.3 V buck/LDO | 1 | $4 | MCU/I²C rail. |
| Internal powered USB hub | 0–1 | $12 | Tidy USB fan-out. |
| DC inlet, switch, fuse, reverse-polarity protection | 1 | $10 | Inlet block. |
| Standoffs, sub-trays, bezel, vents, fan (optional) | — | $30 | Mechanical. |
| Wire, connectors, ribbon, heatshrink | — | $25 | Harness. |
6. Bench rough totals
Section titled “6. Bench rough totals”| Build | Core | Audio | MCU/ctrl | Display | Power/mech | Total (excl. S90) |
|---|---|---|---|---|---|---|
| Budget (MOTU M4) | $220 | $290 | ~$80 | $75 | ~$90 | ≈ $755 |
| Bench baseline (Babyface Pro FS) | $220 | $760 | ~$90 | $90 | ~$90 | ≈ $1,250 |
| Lowest-latency (HDSPe AIO Pro) | $220 | $830 | ~$90 | $90 | ~$90 | ≈ $1,320 |
Excludes the donor S90, tools, PCBs, and your time. Control-surface cost scales with how many knobs/faders you fit.
7. Selected FPGA integration: uncosted BOM
Section titled “7. Selected FPGA integration: uncosted BOM”| Item | Initial qty | Status |
|---|---|---|
| Sipeed Tang Mega 138K Pro PCIe board | 1 | Selected development platform; part/revision, licensing and product form factor still gated.9 |
| Sure AA-AB41164 A2D-PCM1822 stereo ADC | 1 | Initial 2-channel analog input; clock, level and noise tests pending.10 |
| Sure AA-AB41166 ASCM-D2A-PCM5122 stereo DAC | 2 | Initial 4-channel analog output; shared clock and drive tests pending.11 |
| Balanced XLR and unbalanced jack line-I/O front end | Per channel | Connector, buffering/protection and panel layout not yet designed. |
| FPGA-compatible display and touch controller | 1 | RGB888/DVI and touch wiring to be selected and qualified. |
| Keybed scanner/protection and control-I/O harness | 1 set | Direct FPGA GPIO versus nearby scanner MCU remains a measured decision. |
| 12 V FPGA rail and revised system power tree | 1 set | Power and thermal budget unknown; see 08. |
No reliable integrated-system total exists before board pricing, converter measurements, power/analog design, driver effort and product-licence review.
Footnotes
Section titled “Footnotes”-
ASRock, “N100DC-ITX.” https://www.asrock.com/mb/Intel/N100DC-ITX/index.asp ↩
-
RME, “Babyface Pro FS.” https://rme-audio.de/babyface-pro-fs.html ↩
-
MOTU, “M4” ($279.95). https://motu.com/en-us/products/m-series/m4/ ↩
-
snd-hdspedriver for RME HDSPe AIO Pro (maintained fork: Schroedingers-Cat/snd-hdspe). https://github.com/PhilippeBekaert/snd-hdspe ↩ -
Raspberry Pi, “RP2350 datasheet.” https://datasheets.raspberrypi.com/rp2350/rp2350-datasheet.pdf ↩
-
Microchip MCP2221A. https://www.microchip.com/en-us/product/mcp2221a ↩
-
“I²C design mathematics.” https://www.allaboutcircuits.com/technical-articles/i2c-design-mathematics-capacitance-and-resistance/ ↩
-
Waveshare 7EP-CAPLCD. https://www.waveshare.com/7ep-caplcd.htm ↩
-
Sipeed, “Tang Mega 138K Pro Dock.” https://wiki.sipeed.com/hardware/en/tang/tang-mega-138k/mega-138k-pro.html ↩
-
Sure Electronics, “AA-AB41164 A2D-PCM1822.” https://store.sure-electronics.com/product/813 ↩
-
Sure Electronics, “AA-AB41166 ASCM-D2A-PCM5122.” https://store.sure-electronics.com/product/829 ↩