lwip — raw lwIP TCP/IP stack

import lwip

Direct access to the bundled lwIP stack. Most users only need lwip.reset() and lwip.callback(); the higher- level socket module sits on top of this.

lwip.reset()

Re-initialise the entire stack: tear down all PCBs, flush ARP / DNS / routing caches, re-add the loopback interface. Call once at program start (before socket is used) and any time you want a clean slate (e.g. after switching networks).

import lwip
lwip.reset()

lwip.callback() → int

Run the lwIP timer + RX poll once. Returns the number of TCP timer ticks that fired. Most networking code in this port calls this implicitly:

• socket.recv() / socket.accept() poll automatically
• asyncio event loop polls per iteration
• The bundled wget.py / scp.py / sftp.py insert calls in their main loops

You only need to call it explicitly when you’re holding the CPU in a tight Python loop with no socket I/O — typically you wouldn’t.

# Pattern: warm up after eth_init/static
for i in range(5):
    lwip.callback()
    time.sleep_ms(50)

lwip.tcp_info(sock_fileno) — debug

Returns a dict of stats for a TCP socket’s underlying PCB. Useful for diagnosing “why did this stall” problems.

info = lwip.tcp_info(s.fileno())
print(info)
# {'state': 'ESTABLISHED', 'snd_wnd': 65535, ...}

Versions / build

>>> lwip.version()
'2.1.3'

See also

• uc386_net — packet driver detection + interface configuration (DHCP / static)
• socket — the BSD socket API on top

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This is a port-specific module; no upstream-MicroPython counterpart.