Breadboard Ethernet, part 1

Posted on September 4, 2019
Tags: electronics, making

I did this project a year and a half ago, but I only got around to posting about it now. This is part 1 of 2.

There are plenty of ways to add Ethernet to an Arduino-compatible, most based around one of the WizNet chips. This is probably the best way to go if you just want to get Ethernet connectivity in the easiest way possible.

However, I noticed that there is an Ethernet controller, ENC28J60, which is available in a DIP package. I think it’s fun to wire things up myself instead of just using a pre-built module, so I thought I’d try breadboarding a circuit with the ENC28J60.

The one component of the circuit which won’t fit on a breadboard is the MagJack, so I made a simple breakout board to allow the MagJack to be plugged into a breadboard.

Schematic

schematic for Ethernet circuit

Bill of Materials

Ref Description MPN Digi-Key PN
C1, C4, C6-C10 CAP CER 0.1UF 50V X7R RADIAL K104K10X7RF5UH5 BC2665CT-ND
C2, C3 CAP CER 22PF 50V C0G/NP0 RADIAL K220J15C0GF5TL2 BC1005CT-ND
C5 CAP CER 10UF 10V X7R RADIAL FG24X7R1A106KRT06 445-173370-1-ND
J1 CONN MAGJACK 1PORT 10/100 BASE-T RJMG1BD3B8K1ANR RJMG1BD3B8K1ANR-ND
L1 FERRITE BEAD 135 OHM AXIAL 1LN 28L0138-40R-10 240-2439-1-ND
R1-R4 RES 49.9 OHM 1/4W 1% AXIAL RNF14FTD49R9 RNF14FTD49R9CT-ND
R5, R6 RES 120 OHM 1/4W 5% AXIAL CF14JT120R CF14JT120RCT-ND
R7 RES 2.32K OHM 1/4W 1% AXIAL RNF14FTD2K32 RNF14FTD2K32CT-ND
U1 IC ETHERNET CTRLR W/SPI 28SDIP ENC28J60-I/SP ENC28J60-I/SP-ND
Y1 CRYSTAL 25.0000MHZ 20PF T/H ATS25A-E CTX1142-ND
ATMEGA328 ARDUINO PRO MINI 3.3V DEV-11114 1568-1054-ND

Hookup

Start out by connecting wires to power and ground.

Breadboard

Add 0.1µF decoupling capacitors on ENC28J60.

Breadboard

Add 10μF capacitor between VCAP (pin 1) and GND.

Breadboard

Add 25 MHz crystal between OSC1 and OSC2 (pins 23 and 24). Add a 22pF capacitor between OSC1 and GND, and another 22pF capacitor between OSC2 and GND.

Breadboard

Add LED wires and LED resistors.

Breadboard

Add 2.32K resistor between RBIAS (pin 14) and GND.

Breadboard

Add resistors and capacitors to MagJack.

(*) Sorry, capacitors aren’t shown until photo for next step.

Breadboard

Add ferrite bead between TCT and 3.3V.

Breadboard

Add TX and RX wires.

Breadboard

Connect SPI pins to microcontroller.

Breadboard

Connect power buses on the two sides of the breadboard together.

Breadboard

That’s it for the hardware. The second post will cover software and testing.