5-socket limit on Pico as well?

[skyguy]

Anyone know where the limit of 5 sockets originates from?

I came across it on the ESP8266, but I thought it was due to the limited RAM. Now I find that 5 is the limit on the Pico W as well :

`
MPY: soft reboot
MicroPython v1.21.0 on 2023-10-06; Raspberry Pi Pico W with RP2040
Type "help()" for more information.

import socket
s1=socket.socket()
s2=socket.socket()
s3=socket.socket()
s4=socket.socket()
s5=socket.socket()
s6=socket.socket()
Traceback (most recent call last):
File "", line 1, in
OSError: [Errno 12] ENOMEM
`

I have 12 LED's on my network monitor I'd like to activate simultaneously... :-)

[jimmo]

In lwip/opt.h

/**
 * MEMP_NUM_TCP_PCB: the number of simultaneously active TCP connections.
 * (requires the LWIP_TCP option)
 */
#if !defined MEMP_NUM_TCP_PCB || defined __DOXYGEN__
#define MEMP_NUM_TCP_PCB                5
#endif

You can override this if you build your own firmware by adding it to ports/rp2/lwip_inc/lwipopts.h

[skyguy]

Thanks for that - if I can't work around the limit I'll try a custom firmware.

Am I correct in thinking that increasing the number will reserve more RAM for buffers, thus reducing the available RAM for applications?

[jimmo]

That's right. These buffers are allocated in .bss, and MicroPython uses whatever is left to make its heap.