It doesn't work to tie the polling of an underlying NIC driver (eg to check
the NIC for pending Ethernet frames) with its associated lwIP netif. This
is because most NICs are implemented with IRQs and don't need polling,
because there can be multiple lwIP netif's per NIC driver, and because it
restricts the use of the netif->state variable. Instead the NIC should
have its own specific way of processing incoming Ethernet frame.
This patch removes this generic NIC polling feature, and for the only
driver that uses it (Wiznet5k) replaces it with an explicit call to the
poll function (which could eventually be improved by using a proper
external interrupt).
The Wiznet5k series of chips support a MACRAW mode which allows the host to
send and receive Ethernet frames directly. This can be hooked into the
lwIP stack to provide a full "socket" implementation using this Wiznet
Ethernet device. This patch adds support for this feature.
To enable the feature one must add the following to mpconfigboard.mk, or
mpconfigport.mk:
MICROPY_PY_WIZNET5K = 5500
and the following to mpconfigboard.h, or mpconfigport.h:
#define MICROPY_PY_LWIP (1)
After wiring up the module (X5=CS, X4=RST), usage on a pyboard is:
import time, network
nic = network.WIZNET5K(pyb.SPI(1), pyb.Pin.board.X5, pyb.Pin.board.X4)
nic.active(1)
while not nic.isconnected():
time.sleep_ms(50) # needed to poll the NIC
print(nic.ifconfig())
Then use the socket module as usual.
Compared to using the built-in TCP/IP stack on the Wiznet module, some
performance is lost in MACRAW mode: with a lot of memory allocated to lwIP
buffers, lwIP gives Around 750,000 bytes/sec max TCP download, compared
with 1M/sec when using the TCP/IP stack on the Wiznet module.
