Converting a Duet Wifi to a Duet Ethernet

[dc42]

Nice pictures! For anyone else doing this:

• I recommend you remove the SD card from its socket before doing any soldering or desoldering in that area.

• On a Duet Ethernet we solder low-profile header pin strips into the Duet motherboard, then plug the Ethernet board into those. That would be why the pins didn't fit the board.

[tjschweizer]

Thanks!

Yeah, I got some flux in the SD card socket and now it is a little sticky. I should've pulled the card out, probably would have helped. Lived and learned.

[dc42]

I was thinking more of possible heat damage to the SD card.

[fma]

Thanks for this feedback. I still hesitate in switching to the wifi module+antenna, or an ethernet module…

[dc42]

You are right to hesitate, unless you have the proper hot air rework equipment and experience of using it.

[lolorc]

btw, what's the max connexion speed between the ethernet module and the duet board ? I guess it uses SPI.

[fma]

I'm not afraid of soldering/desoldering; I did this on much tiny chips

[dc42]

@lolorc:

btw, what's the max connexion speed between the ethernet module and the duet board ? I guess it uses SPI.

40Mbits/sec.

[lolorc]

thanks,
in the mean time I came across https://javakys.wordpress.com/2014/10/29/the-second-trial-on-enhancing-the-throughput-of-w5500/ concluding with "To conclude, W5500 can achieve the throughput over than 13Mbps under 42MHz SPI Clock.."

[dc42]

Thanks for the link. I looked at using buffer sizes larger than the default 2K, however the W5500 has only 32K of buffer space total which has to be divided between the 8 possible sockets. So if you increase the buffer size on one socket, you have to reduce it on others.

I found that one of the biggest limiting factors is the speed of writing to the SD card. On the Duet WiFi I obtained 3Mbytes/sec upload speed if the Duet main processor threw the data away instead of writing it to SD card. The speeds quoted by the SD card manufacturers are for writing large blocks of data as happens in a digital camera when you take a photo. The Duet doesn't have enough RAM to write such large blocks.