wiznet: spi baudrate declared as 2 and 20 MHz ?!

massimosala commented 5 months ago

Checks

[X] I agree to follow the MicroPython Code of Conduct to ensure a safe and respectful space for everyone.
[X] I've searched for existing issues matching this bug, and didn't find any.

Port, board and/or hardware

rp2

MicroPython version

Micropython 1.22.2

Reproduction

network_wiznet5k.c #define MICROPY_HW_WIZNET_SPI_BAUDRATE (2000000) mpconfigboard.h #define MICROPY_HW_WIZNET_SPI_BAUDRATE (20 * 1000 * 1000)

Expected behaviour

Which is the right speed? Should I try with 20 MHz ?

Observed behaviour

Initializing the SPI bus at 2 MHz works.

Additional Information

No, I've provided everything above.

robert-hh commented 5 months ago

As far as I understand it, both settings are fine. The setting in network_wiznet5k.c is the default value, which can be overridden by a board definition. This approach of default + specific defines is used at many place in the code. By itself this is not a bug.

massimosala commented 5 months ago

Hi Robert

Thanks for your fast reply.

I see. However the online examples doesn't help regular Python users to understand this topic.

The micropython official doc says

class WIZNET5K ... allows you to control WIZnet5x00 Ethernet adaptors based on the W5200 and W5500 chipsets

Unfortunately there is only one example... referring to the Pyboard:

import network
nic = network.WIZNET5K(pyb.SPI(1), pyb.Pin.board.X5, pyb.Pin.board.X4)

I am using the Wiznet W5500-EVB-Pico firmware with a regular rp2 (non WiFi) board, wired to an external W5500 module.

The rp2 and the w5500 are mounted on a breadboard, with plain wires to connect the signals. I tested up to 20 MHz and it works (the program on the rp2 uses up to 3 tcp connections; running over 1 hour without problems).

I suggest to improve the documentation on these web pages:

Firmware download

This firmware isn't limited to Wiznet W5500-EVB-Pico boards, it works also with rp2 plus external W5500 module.

Wiznet W5500-EVB-Pico

To use a Raspberry Pico with an external Wiznet 5500 module, you can flash the W5500 EVB PICO firmware.

Example to initialize the network card:

from machine import Pin, SPI
from network import WIZNET5K, hostname
spi = SPI(0, spi_mhz * 1_000_000, mosi = Pin(19), miso = Pin(16), sck = Pin(18))
nic = WIZNET5K(spi, Pin(17), Pin(20))

Recommendations: The speed of the spi bus wired to the W5500 can be in the range 2 .. 20 MHz. The maximum speed can be used with the chips soldered on a PCB and a good routing of the signal traces. Using a breadboard, it is safer to stay under 8 MHz.

massimosala commented 5 months ago

Robert, can you pls add the tag "Documentation" to this issue? I cannot see how to do.

jonnor commented 4 months ago

Improvements to the documentation would be much appreciated!

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