Imported from GitHub: valletw/esp-atx-power · commit aa33f61 · license MIT

Description

ESP32 ATX Power Controller

README

ESP32 ATX Power Controller

The purpose of this project is to control a computer remotely by connecting directly to the ATX motherboard power IO control. The control will be done with Home Assistant by using ESPHome firmware.

Custom software could be written by using ESP-IDF SDK but it is not the purpose of this project.

Hardware

Double 2.54mm pin headers are set for each ATX functionalities to manage:

• PWR SW: ATX power button
• RST SW: ATX reset button
• PWR LED: ATX power state LED
• HDD LED: ATX HDD activity LED

Two status LED are available:

• PWR: 3.3V state
• STAT: System status controlled by software

Two buttons are available for ESP32 boot sequence:

• BOOT: Control processor download mode on boot
• EN: Control processor reset

For advanced debug, the following connectors are available:

• 2x5 1.27mm pins header JTAG/SWD for external probe
• 4-pins Molex connector for UART

Components choice

This project is based on an ESP32-C3 module to simplify design and ensure good WiFi performance (with external antenna connector). ESP32 has been selected for the big community to generate software and the frameworks available. Espressif hardware design rules has been take into account following there documentation

For easy debug and flashing, ESP32 with USB-CDC and JTAG support has been selected. It allows to remove the USB-UART bridge of the previous design.

The optocouplers for electric isolation have been selected following the PiKVM project experience. In the DIY PiKVM V2 instructions, the OMRON reference is recommended. Others relays/optocouplers may not be sensitive enough or low-level controlled.

The 3.3V to power all the components is generated from an LDO using the 5V of the USB socket. It can also be powered from external 5V on pins header. Both external 5V and USB can be connected at the same time, a power MUX is used to switch between both sources.

All others components has been selected from JLCPCB catalogue to minimize the cost and the assembly fees.

Manufacturing

The board is manufactured by JLCPCB, here is the details you will require to generate an order.

Note: JLCPCB requests some modifications on output files, do not use direct export from KiCad (check the FAQ)

PCB

Files: Gerbers

Configuration	Value
Base Materiel	FR-4
Layers	4
Dimensions	76.56 x 25.10
Different design	1
Delivery format	Single PCB
PCB thickness	1.6
PCB color	Green (other colors have fees)
Silkscreen	White
Materiel type	FR4-Standard TG 135-140
Surface finish	HASL
Specify layer sequence	F_Cu / In1_Cu / In2_Cu / B_Cu
Impedance control	Yes
Layer stackup	JLC04161H-7628
Via covering	Tented
Min via hole size/diameter	0.3mm/0.45mm
Remove order number	Specify a location

Note: All options have not been detail here, keep default value.

Assembly

Files: BOM, CPL

Configuration	Value
PCBA type	Economic
Assembly side	Top
Tooling holes	Added by JLCPCB

Verify "pick & place" orientations and positions on the web viewer

JLCPCB will add 2 tooling holes for assembly (1 mm diameter near the board corners).

Note: All options have not been detail here, keep default value.

ESP32 Pinout

For those who want to reuse this project, here is the ESP32 pinout to manage the different input/output.

Name	Pin	Direction
System Status LED	IO8	Output (strapping pin)
ATX Power Button	IO0	Output
ATX Reset Button	IO1	Output
ATX Power State	IO3	Input
ATX HDD Activity	IO10	Input

ESPHome configuration

Device must be setup via USB connection the first time to flash the customized firmware with sensors/buttons configuration.

Once it has been configured successfully, you should fix the device IP on your router for easier Home Assistant configuration.

Note: Installation can be bypassed if already done or you can use docker image. Check ESPHome documentation for more details.

Installation

pip install esphome
# Ensure your user session has the correct permission for serial port.
sudo usermod -a -G dialout <USERNAME>

Customize

Depending of your installation and network, a secrets.yaml file must be create with your specific configuration.

# secrets.yaml
hostname: MyControllerHostname
wifi_ssid: MySSID
wifi_password: MyStrongPassphrase
wifi_fb_ssid: ATX Controller Fallback Hotspot
wifi_fb_password: StrongPassphrase
ota_password: MyOTAPassphrase
api_key: 32BytesBase64String

Compile and flash

# Generate the firmware.
esphome compile esphome.yaml
# Flash the firmware to the ESP.
esphome run esphome.yaml
# Get logs.
esphome logs esphome.yaml