Hardware Overview
This project forms the foundation for all components in the home automation system; it implements a stable 5.1V power supply and provides 10/100 Mbps network access to every component.
For managing the centralized power and data distribution, the UISP Switch Plus[6] is highly recommended. It provides a professional way to inject 12V/24V passive PoE and manage network traffic for multiple sensor nodes from a single point.
This architecture ensures that the cable length between the centralized power source and the sensor does not matter.
Figure 1: Stabilized power supply and SPI Ethernet connection schematic.
Wiring Matrix
Connect the power and the network module to the Pi Zero 2 W using the following GPIO configuration.
| LM2506 (Step-down module DC-DC)[1] | Pi Physical Pin | Wiring |
|---|---|---|
| Out (+) | Pin 2 (5V) | Orange |
| Out (-) | Pin 6 (GND) | Blue |
| LM2506 (Step-down module DC-DC)[1] | RJ45 socket[3] | Wiring |
| In (+) | Pin 4 | Blue |
| In (+) | Pin 5 | Blue / White |
| In (-) | Pin 7 | Brown / White |
| In (-) | Pin 8 | Brown |
| RJ45 connector[4] | RJ45 socket[3] | Wiring |
| Pin 1 | Pin 1 | Green / White |
| Pin 2 | Pin 2 | Green |
| Pin 3 | Pin 3 | Orange / White |
| Pin 6 | Pin 6 | Orange |
| ENC28J60[2] | Pi Physical Pin | Wiring |
| Vcc | Pin 17 (3.3V) | Orange |
| CS | Pin 24 (CE0) | Orange / White |
| SI | Pin 19 (Mosi) | Green |
| WOL | not connected | |
| CLKOUT | not connected | |
| Gnd | Pin 25 (Gnd) | Blue |
| Reset | Pin 18 (GPIO 5) | Brown / White |
| SCK | Pin 23 (SCLK) | Blue / White |
| SO | Pin 21 (Miso) | Brown |
| INT | Pin 22 (GPIO 6) | Green / White |
⚠️ Critical Calibration of LM2596[1]
Adjust the potentiometer to output exactly 5.1V before connecting to the Pi.
List of Materials (BOM)
Referenced components used in this manufacturing process.
| ID | Item | Pinnout Diagram | Description/Source |
|---|---|---|---|
| [1] | LM2596 | Available on Sigmanortec. | |
| [2] | ENC28J60 | Pinout | Available on Sigmanortec. |
| [3] | RJ45 socket | Available on TME. | |
| [4] | RJ45 connector | Pinout | Available on TME. |
| [5] | Raspberry Pi Zero 2 W | Pinout | Available on Emag. |
| [6] | UISP Switch Plus | Available on EU Store. |
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