micropy-ENC28J60

ENC28J60 Ethernet chip driver for MicroPython v1.17 (RP2)

Rationale

ENC28J60 is a popular and cheap module for DIY projects. At the moment, however, there is no driver for the MicroPython environment. The Python implementation seems easy for further improvements and self adaptation.

Installation

Copy enc28j60.py to your board into /enc28j60 directory.

Wiring

Wiring requires pins for SPI: SCK, MISO, MOSI and ChipSelect and optionally Interrupt. Example wiring that uses SPI1 bus (any SPI bus can be used):

ENC28J60 Module	RP2040 Board	Notes
VCC	3V3	requires up to 180 mA
GND	GND
SCK	GP10	SPI1 SCK
SI	GP11	SPI1 MOSI/TX
SO	GP8	SPI1 MISO/RX
CS	GP13	SPI1 CSn
INT	GP15	Optional

To do

• interrupt handler

Example code

Packet transmission

Example of packet transmission to broadcast ethernet address:

from machine import Pin, SPI
from enc28j60 import enc28j60

spi1 = SPI(1, baudrate=10000000, sck=Pin(10), mosi=Pin(11), miso=Pin(8))
eth = enc28j60.ENC28J60(spi1, Pin(13))
eth.init()

srcMac = eth.getMacAddr()
tgtMac = bytearray([0xFF,0xFF,0xFF,0xFF,0xFF,0xFF])
payLoad = bytearray(64)
pktType = bytearray([(len(payLoad) >> 8) & 0xFF, len(payLoad) & 0xFF])

eth.SendPacket([tgtMac, srcMac, pktType, payLoad])

Packet reception

Example of packet reception:

from machine import Pin, SPI
from enc28j60 import enc28j60

spi1 = SPI(1, baudrate=10000000, sck=Pin(10), mosi=Pin(11), miso=Pin(8))
eth = enc28j60.ENC28J60(spi1, Pin(13))
eth.init()

print("myMac:", ":".join("{:02x}".format(c) for c in eth.getMacAddr()))
print("ENC28J60 revision ID: 0x{:02x}".format(eth.GetRevId()))

rxBuf = bytearray(enc28j60.ENC28J60_ETH_RX_BUFFER_SIZE)

while eth.GetRxPacketCnt():
    rxLen = eth.ReceivePacket(rxBuf)
    print('rxLen:', rxLen, 'srcMac:', ":".join("{:02x}".format(c) for c in rxBuf[6:12]))

IPv4 simple suite for polling mode

Please refer to examples/Ntw.py file for details.

The file contains roughly written procedures for handling IP protocols in polling mode:

• IPv4 for not fragmented packets only, single static IP address
• ARP for IPv4 over Ethernet, simple ARP table
• ICMPv4: rx Echo Request and tx Echo Response
• UDPv4: rx and tx
• Simple UDP Echo server

MicroPython v1.17 for Raspberry Pi Pico does not include socket library. It also does not allow to run more than 2 threads at the time. It is hard to mimic network sockets in such environment. So polling mode seems reasonable solution.

from machine import Pin
from machine import SPI
import Ntw

if __name__ == '__main__':
    # Create network
    nicSpi = SPI(1, baudrate=10000000, sck=Pin(10), mosi=Pin(11), miso=Pin(8))
    nicCsPin = Pin(13)
    ntw = Ntw.Ntw(nicSpi, nicCsPin)

    # Create UDP Echo server
    udpecho = Ntw.Udp4EchoServer(ntw)

    # Bind UDP Echo server to UDP port 7
    ntw.registerUdp4Callback(7, udpecho)

    # main loop
    while True:
        # Receive and process packets
        ntw.rxAllPkt()