Remora for RP2040

I'm not an electronics guy, but have been looking on how to use the Pico in a real system. I've got a G540 and some old parallel port breakout boards kicking around so I'm thinking of a a carrier board with a DB25 connector. Question is, what would be the basic requirements to add to the board? 

I have not looked at the pinout for the Pico W5500 module to see if it is compatible with the A1 PicoBOB, and the B1 does not have W5500 as it was designed to be the simplest solution for GRBLHAL, but this might give you some ideas anyhow.

github.com/Expatria-Technologies/PicoBOB...540-support-overview

drewnabobber wrote:

I have not looked at the pinout for the Pico W5500 module to see if it is compatible with the A1 PicoBOB, and the B1 does not have W5500 as it was designed to be the simplest solution for GRBLHAL, but this might give you some ideas anyhow.

github.com/Expatria-Technologies/PicoBOB...540-support-overview

Thanks, this will be a great start!!! Unfortunately the W5500 uses some of the PicoBOB pins so some small routing modifications will be needed.

Came up with this using the same SPI pinout as the Wiznet module.  Should be the MVP for Remora on RP2040 and a great plugin for G540.  Placement looks good, I'll route it when I get a chance.

Got this routed and ready for fab.  Going to let it stew over the weekend  Please let me know if you have any feedback.  I considered adding the spindle encoder interface from the FlexiHAL on here as there are a few free pins, but between the differential transceiver and the voltage translation requirement I have left it off to keep the design as simple and focused (cheap) as possible.  Perhaps an encoder focused board like our EtherHAL prototype would be interesting to consider?

 

Could you design the board to take a spindle encoder and break out any extra pins for people to expand it themselves but have it made with them depopulated?

No sense leaving things on the table if you can help it

Will think on a better way to do it. Left it off because between another rj45 connector plus at least two more ics it made everything bigger and more busy than I was going for. We already have the encoder on FlexiHAL if people are going that direction. Maybe use a smaller connector.  Not sure how many users are going to be interested in soldering their own parts so if we do it should be done right.

I will route the unused pins to the programming header and then they will be available for playing around with external circuits.

Before heading to the airport for the flight home I loaded on KiCad, spent the time at the airport comparing schematics and scratching my head. I get home and you've already got it nearly done!!! Wow. Looks great.

It would be good to have the spare pins available on the header.

GPIO29, 25, 24, and 23 are not available on the Pico but could also be available. An onboard led (GP29) would be handy for showing comms status, testing etc.

Did you have a plan for pin allocation? I've adopted the static config ability from FlexiHal together with the original JSON config so we could have the static config ready to go for this out of the box.

Also, I think I can improve the Ethernet performance. I found my Mbed STM32 code that I was playing with for the W5500 in interrupt mode (need to finished that for the STM32....). The RP2040 W5500 code already as DMA capabilities so we just need to take advantage of the receive interrupt vs polling. Not that it will impact the second core running the main code, but at least the servo thread can be optimised some.
 

I've just had a question on one of the YouTube videos on the NVMPG. When you look at the pin routing, maybe make the spare pins on the UART capable pins. That way people could also attach a TTL serial to RS232 adaptor and use the NVMPG in a really simple way.

Would need the opto's for the encoder like Arron suggested for two / 3 channels. Maybe that could be an add on board including a MAX232.

www.aliexpress.com/item/4000587246651.ht....product.mainProduct

So some spare 3V3 and ground pins would be good to.

Just for my understanding. Why does the PicoBob use transistors on each individual output rather than a package like the SN74ALVC164245?

The NVEM / EC300 / EC500 use this IC for the outputs and inputs. On the NVEM it is directly used to drive the stepper outputs.