# Add a LAN port using the SPI bus

<abstract>
How to wire and configure an SPI Ethernet adapter based on the [Microchip ENC28J60](http://ww1.microchip.com/downloads/en/DeviceDoc/39662e.pdf) 
like the [Mikroe ETH click board](https://www.mikroe.com/eth-click) or [TZT ethernet adapter](https://it.aliexpress.com/item/1pcs-lot-ENC28J60-SPI-interface-network-Ethernet-module-mini-version-raspberry-lcd-raspberri-pi-zero-2/32804747718.html?src=google&albslr=222200202&isdl=y&aff_short_key=UneMJZVf&source=%7Bifdyn:dyn%7D%7Bifpla:pla%7D%7Bifdbm:DBM&albch=DID%7D&src=google&albch=shopping&acnt=494-037-6276&isdl=y&albcp=664365055&albag=32654331814&slnk=&trgt=61865531738&plac=&crea=it32804747718&netw=g&device=c&mtctp=&aff_platform=google&gclid=CjwKCAjwt5DXBRAtEiwAa3vyEmJLtMchDLF8ycyXVAUbc_BtXhalOVtikoZLryrh47zfTbupClwMoxoCTtsQAvD_BwE&gclsrc=aw.ds).
</abstract>

<img src="./F7916432-01.jpg" class="img-responsive"  width="20%">
[Mikroe ETH click board](https://www.mikroe.com/eth-click)

### Wirings


	ENC28J60  |  CM3-Panel	
	----------|-----------------
	     RST# | NC
	     INT# | GPIO40
	      CS# | SPI0_CE0 (GPIO36)
	      SCK | SPI0_SCLK (GPIO39)
	      SDO | SPI0_MISO (GPIO37)
	      SDI | SPI0_MOSI (GPIO38)
	      3V3 | 3V3
	      GND | GND

Save this file in __/boot/overlays/enc28j60-cm3panel.dts__:

	// Overlay for the Microchip ENC28J60 Ethernet Controller
	// Acme Systems CM3-Panel 
	// http://www.acmesystems.it/CM3-PANEL
	
	/dts-v1/;
	/plugin/;
	
	/ {
		compatible = "brcm,bcm2708";
	
		fragment@0 {
			target = <&spi0>;
			__overlay__ {
				/* needed to avoid dtc warning */
				#address-cells = <1>;
				#size-cells = <0>;
	
				status = "okay";
	
				eth1: enc28j60@0{
					compatible = "microchip,enc28j60";
					reg = <0>; /* CE0 */
					pinctrl-names = "default";
					pinctrl-0 = <&eth1_pins>;
					interrupt-parent = <&gpio>;
					interrupts = <40 0x2>; /* falling edge */
					spi-max-frequency = <12000000>;
					status = "okay";
				};
			};
		};
	
		fragment@1 {
			target = <&spidev0>;
			__overlay__ {
				status = "disabled";
			};
		};
	
		fragment@2 {
			target = <&gpio>;
			__overlay__ {
				eth1_pins: eth1_pins {
					brcm,pins = <40>;
					brcm,function = <0>; /* in */
					brcm,pull = <0>; /* none */
				};
			};
		};
	
		__overrides__ {
			int_pin = <&eth1>, "interrupts:0",
			          <&eth1_pins>, "brcm,pins:0";
			speed   = <&eth1>, "spi-max-frequency:0";
		};
	};

Compile it by typing:

	sudo dtc -@ -I dts -O dtb -o /boot/overlays/enc28j60-cm3panel.dtbo /boot/overlays/enc28j60-cm3panel.dts 

Add this line in __/boot/config.txt__ and reboot:

	dtoverlay=spi-gpio35-39
	dtoverlay=enc28j60-cm3panel

### Disadvantages of this solution

The Microchip ENC28J60 doesn't have a MAC address so you have to configure it by software. To avoid this problem 
the right chip is [ENC424J600](https://www.microchip.com/wwwproducts/en/en542414).

@include='bio_tanzilli'