Your idea,
on working hardware.

I'm Pasco, an electrical engineer in Austin, Texas, with 25 years of experience. I design the circuit and PCB, write the firmware, and build the enclosure, so your idea becomes a prototype you can hold, test and show.

Start a project See selected work
Design
EasyEDA · Altium Designer · Eagle · schematic and PCB layout · board bring-up
Firmware
STM32 · ESP32 (ESP-IDF, ESPHome) · Silicon Labs EFR32
Interfaces
USB · UART · I2C · BLE · Zigbee · Thread · Wi-Fi
Workshop
Laser cutters · UV printer · 3D printers for enclosures

Selected work

Recent builds, documented end to end.

Doer USB GPIO board in its 3D-printed case with a color-coded pinout label, connected by USB

01 · Board and firmware

A USB GPIO board for any computer

Doer USB GPIO gives a PC, Mac or Linux machine Raspberry Pi-style pins over USB. Starting from an open-source concept, I redesigned the board from schematic to PCB around an STM32F070, wrote its firmware with a bootloader for updates in the field, gave it a 3D-printed case with a color-coded pinout, and published a Python library with a familiar RPi.GPIO-style API.

Hardware
STM32F070 (Cortex-M0), CH340 USB-serial, AMS1117 3.3 V regulator, Raspberry Pi pinout
Firmware
Bootloader and application, DMA-driven UART protocol, GPIO, PWM, 12-bit ADC, I2C
Outcome
Boxed product, DoerGPIO 1.1 on PyPI, open-source firmware

Watch the demo Firmware on GitHub ↗ Python library ↗

Mainboard of the IOT7 Wi-Fi multimeter with its ESP32-S2 module

02 · Firmware

Standalone firmware for a Wi-Fi multimeter

I replaced the vendor-locked firmware on a battery-powered ESP32-S2 multimeter with my own: browser-based Wi-Fi setup, a local web interface, over-the-air updates and a fix for a USB crash in the original. The work started with a full, verified flash backup, so the device can always be restored.

Hardware
ESP32-S2, 4 MB flash
Firmware
ESP-IDF, web provisioning, OTA updates, image size reduction
Outcome
Vendor-free firmware, open source

Source on GitHub ↗

W1700K router mainboard connected to a Silicon Labs debugger through its J10 header

03 · Reverse engineering

Unlocking the hidden radio in an ISP router

The Quantum Fiber W1700K carries a Silicon Labs EFR32MG21 radio chip that its stock firmware keeps locked away. I found its undocumented debug header, decoded the host-to-radio UART protocol, and built tooling that flashes it with BLE, Zigbee or Thread firmware.

Hardware
Airoha AN7581 SoC, EFR32MG21
Work
OpenWrt install over UART, SWD debugging, protocol analysis
Outcome
BLE, Zigbee and Thread firmware, open source

Read the build log Source on GitHub ↗

Working with me

For founders and small teams who need a circuit designed, firmware written or a prototype built, without hiring a hardware team.

Start a project

Fixed prices, agreed in writing before work starts.

  1. 1

    Send me the problem

    A short description, a sketch or a link is enough. No call needed.

  2. 2

    A written proposal within 24 hours

    Scope, approach, risks, price and timeline, all in writing.

  3. 3

    Progress you can see every week

    Photos, video demos and notes until the work is done.

ServiceWhat you getPrice
Feasibility reviewA written answer to "can this be built, and how?", with parts, a rough BOM and a timeline$500
Circuit and PCB designSchematic, layout and a brought-up, tested board, with design files you ownfrom $2,000
Firmware developmentFirmware for STM32, ESP32 or EFR32: drivers, protocols, bootloaders and OTA updatesfrom $1,500
Prototype sprintBoard, firmware and enclosure working together, in two to three weeksfrom $3,000
Reverse engineeringCustom firmware or local control for an existing devicefrom $1,500