alxhub/osdev-hatAn operating system development HAT for Raspberry Pi
Osdev hat is an open-source printed circuit board by alxhub, from the alxhub/osdev-hat repository on GitHub, published under the MIT licence. It is a 2-layer board of 65 × 56.5 mm with 60 parts on 96 nets, routed with 388 tracks and 41 vias.
It is built around the PCA9555DB and TPS25942ARVCT. Its parts include 29 resistors, 16 diodes, 6 capacitors, 6 connectors and 2 ICs.
The OSDev HAT is a Raspberry Pi HAT which makes operating system development against the Raspberry Pi as a host significantly easier.
The HAT contains a socket for an ESP32 (I use the Sparkfun ESP32-S3 Thing Plus). The ESP32 is capable of turning the Pi on and off and communicating with it over UART. A custom bootloader based on raspbootin allows the Pi to boot from a kernel loaded from the ESP32.
Effectively, this turns the ESP32 into a wireless remote controller for the Pi: turning it on, loading a kernel, monitoring the console output over UART, sending commands, etc.
Planned features include:
This project is in early stages, and currently contains the untested PCB design:
| Qty | Value | Footprint | References |
|---|---|---|---|
| 16 | 470 | Resistor_SMD:R_0603_1608Metric | R1, R2, R3, R17, R18, R19, R20, R21, R22, R23, R24, R25, R26, R27, R28, R29 |
| 16 | LED | LED_SMD:LED_0603_1608Metric | D1, D2, D3, D4, D5, D6, D7, D8, D9, D10, D11, D12, D13, D14, D15, D16 |
| 6 | ? | Resistor_SMD:R_0603_1608Metric | R7, R9, R10, R11, R12, R14 |
| 3 | 100k | Resistor_SMD:R_0603_1608Metric | R6, R8, R13 |
| 2 | 0.1uF | Capacitor_SMD:C_0603_1608Metric | C2, C4 |
| 2 | 10k | Resistor_SMD:R_0603_1608Metric | R15, R16 |
| 2 | 1uF | Capacitor_SMD:C_0603_1608Metric | C3, C5 |
| 2 | 5.1k | Resistor_SMD:R_0603_1608Metric | R4, R5 |
| 2 | Conn_01x04_Socket | Connector_JST:JST_SH_SM04B-SRSS-TB_1x04-1MP_P1.00mm_Horizontal | J4, J5 |
| 1 | ? | Capacitor_SMD:C_0603_1608Metric | C6 |
| 1 | C_Polarized | Capacitor_THT:C_Radial_D5.0mm_H5.0mm_P2.00mm | C1 |
| 1 | Conn_01x12_Socket | Connector_PinSocket_2.54mm:PinSocket_1x12_P2.54mm_Vertical | J2 |
| 1 | Conn_01x16_Socket | Connector_PinSocket_2.54mm:PinSocket_1x16_P2.54mm_Vertical | J3 |
| 1 | D_Schottky | Diode_SMD:D_0402_1005Metric | D_ESP1 |
| 1 | PCA9555DB | Package_SO:SSOP-24_5.3x8.2mm_P0.65mm | U2 |
| 1 | Raspberry_Pi_4 | PiHat:RPI_Hat_B+ | J1 |
| 1 | TPS25942ARVCT | ul_TPS25942ARVCT:RVC0020A | U1 |
| 1 | USB_C_Plug | Connector_USB:USB_C_Receptacle_GCT_USB4085 | P1 |
It measures 65 × 56.5 mm and has 2 copper layers, 1.6 mm thick.
60 parts, built around the PCA9555DB and TPS25942ARVCT. The full list of its parts is on this page, with links to each part's symbol and footprint where PCBKit's library has them.
From the alxhub/osdev-hat repository on GitHub, at the commit this page was made from: the board is osdev_hat/osdev_hat.kicad_pcb and its schematic osdev_hat/esp32.kicad_sch. PCBKit opens the board in the browser, with nothing to install.
Its repository publishes it under the MIT licence: you may reuse it on that licence's terms (keep the author's notice, and for a copyleft licence share your changes alike).
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