PicoW + WIZnet UDP Ouroboros

ouroboros.py

# SPDX-FileCopyrightText: 2023 anecdata
#
# SPDX-License-Identifier: MIT

import time, gc, random, board, busio, digitalio
from secrets import secrets
# for PicoW server:
import wifi, socketpool, ipaddress
# for WIZnet client:
from adafruit_wiznet5k.adafruit_wiznet5k import WIZNET5K
import adafruit_wiznet5k.adafruit_wiznet5k_socket as socket

__version__ =  "0.0.2"

PORT = 5000
SERVER_TIMEOUT = 5
CLIENT_TIMEOUT = 5
BACKLOG = 1
INTERVAL = 5

print(f"PicoW + WIZnet UDP Ouroboros Test")

# Connect to Wi-Fi
wifi.radio.connect(secrets['ssid'], secrets['password'])
time.sleep(0.1)  # IP address can lag connect return by 10s of ms
print(f"PicoW Server IP Address: {wifi.radio.ipv4_address}")

# PicoW server address
HOST = str(wifi.radio.ipv4_address)

# PicoW socketpool
pool = socketpool.SocketPool(wifi.radio)

# WIZnet Ethernet Hat on Raspberry Pi Pico [W]
cs = digitalio.DigitalInOut(board.GP17)
spi = busio.SPI(board.GP18, MOSI=board.GP19, MISO=board.GP16)
eth = WIZNET5K(spi, cs)
eth_ip = eth.pretty_ip(eth.ip_address)
print(f"WIZnet Client IP Address: {eth_ip}")

# Set up PicoW server socket
print(f"Create PicoW server socket", (HOST, PORT))
s_sock = pool.socket(pool.AF_INET, pool.SOCK_DGRAM)
s_sock.settimeout(SERVER_TIMEOUT)
s_sock.bind((HOST, PORT))

# try to consume our own data w/o async...
orig = buf = bytearray()
buf_size = 1
while True:
    print("-"*25)
    print(f"Available heap {gc.mem_free()} --> ", end="")
    del(orig)
    del(buf)
    gc.collect()
    print(f"{gc.mem_free()}")

    orig = bytearray(''.join(random.choice("0123456789ABCDEF") for _ in range(buf_size)))
    buf = bytearray(buf_size)

    # WIZnet new client socket
    print(f"Create WIZnet client socket")
    c_sock = socket.socket(socket.AF_INET, socket.SOCK_DGRAM)
    c_sock.settimeout(CLIENT_TIMEOUT)

    # WIZnet client sends data
    addr = (HOST, PORT)
    size = c_sock.sendto(orig, addr)
    # print(f"Client sent {orig} {size} bytes")  # WIZnet size always = None
    print(f"Client sent {orig} {buf_size} bytes to {addr}")  # fudge for now...

    # PicoW server receives data
    size, addr = s_sock.recvfrom_into(buf)
    print(f"Server received {buf[:size]} {size} bytes from {addr}")

    # PicoW server sends data back
    size = s_sock.sendto(buf[:size], addr)
    print(f"Server sent {buf[:size]} {size} bytes to {addr}")

    # WIZnet client receives data back
    size, addr = c_sock.recvfrom_into(buf)
    print(f"Client received {buf[:size]} {size} bytes from {addr}")

    # WIZnet client socket close
    c_sock.close()

    # grow the buffer only if it's still smaller than the low-level buffers
    buf_size = 2 * buf_size if (size >= buf_size) else size
    print(f"Next buffer size {buf_size}")
    time.sleep(INTERVAL)

Using this hardware:
https://gist.github.com/anecdata/75ab1f977782008d33b5b3c6201e6dc1

1472 bytes = one packet 1500-byte MTU

• When >1472 bytes are sent to the Pico W UDP socket, the library reports only the first 1472 bytes received
• When >1472 bytes are sent to the WIZnet UDP socket, the library reports 0 bytes received (after a delay of several seconds)

WIZnet W5100S "Support 4 independent SOCKETs simultaneously" and has "Internal 16Kbytes Memory for TX/ RX Buffer"
https://www.wiznet.io/product-item/w5100s/

WIZnet W5500 "Supports 8 independent sockets simultaneously" and has "Internal 32Kbytes Memory for Tx/Rx Buffers"
https://www.wiznet.io/product-item/w5500/