Sammy C21 for display over CAN?

CNCModeller

Hi All,
I'd like to remote mount a 12864 display, I've used screened scart cable in the past but was wondering if I could redefine the pins on a Sammy C21 as a set of 12964 display headers? Or perhaps a panel due could be connected that way too? I've had a look at the Sammy reference but I'm getting the impression it's only really intended for normal IO.

Any constructive thoughts would be much appreciated.

All the best
Barry M

jay_s_uk

@CNCModeller i don't think theres provision for either in the expansion board firmware.
just at a guess, the correct info would need adding to the CAN packets and then the paneldue and/or 12864 code would need moving over.
the other limit for the 12864 display would be how to serve the menu pages etc as there would be no local storage.

CNCModeller

@jay_s_uk said in Sammy C21 for display over CAN?:

the other limit for the 12864 display would be how to serve the menu pages etc as there would be no local storage.

Apologies if this is a daft question, but could the 12864 header pins not "just" be replicated on the Sammy? I don't understand why that would require local storage? Obviously "just"= sending pin data over CAN and repurposing all of the pins with new firmware, so not exactly simple.

I only ask as I'm using CAN on another project and it's making my life so much easier than using old school wiring looms.

Anyway just thinking out loud.

Cheers
Barry M

jay_s_uk

@CNCModeller well the 12864 display renders all the menu files off the sd card in the main board. There is nothing in the firmware for it to display.

gloomyandy

@jay_s_uk I think the suggestion is to in effect remote the SPI device over CAN. I'm sure that could be done, however I've no idea what impact that would have on other CAN devices or how well the display would work (currently the Duet3 runs the CAN-FD bus at 1Mbit/S, typically SPI toa display runs at 2MBit/S plus there will be the additional overhead ).

Running the UART interface (used for the panelDue interface) would probably be simpler. But in that case it might just be easier to just use a UART connection....

CNCModeller

@gloomyandy said in Sammy C21 for display over CAN?:

@jay_s_uk I think the suggestion is to in effect remote the SPI device over CAN. I'm sure that could be done, however I've no idea what impact that would have on other CAN devices or how well the display would work (currently the Duet3 runs the CAN-FD bus at 1Mbit/S, typically SPI toa display runs at 2MBit/S plus there will be the additional overhead ).

Running the UART interface (used for the panelDue interface) would probably be simpler. But in that case it might just be easier to just use a UART connection....

Thanks @gloomyandy that's useful information. I might give a dedicated point to point link a go for my 12864 display with a couple of Arduinos and this CANSerial library.

The scart cable I'm using is expensive so a couple of Arduinos and a twisted pair would likely be cheaper.

Will report back if I get anywhere.

Many thanks
Barry M

DIY-O-Sphere

@CNCModeller
I'm not sure what you want to do with the display, but maybe an external solution would be an alternative. There are several projects about this. Here is an example.

T3P3Tony

@CNCModeller we have discussed the concept of attaching a screen to the CAN FD bus in a similar way to how the PanelDue is attached via UART. That screen would need to have sufficient space for the UI (PanelDue like, 12864 like or otherwise) locally and then update is a method similar to the panel due (data from the the object model in one way or another).

I don't think tunneling SPI (or UART) over the CAN bus is the way to go.

CNCModeller

@T3P3Tony said in Sammy C21 for display over CAN?:

@CNCModeller we have discussed the concept of attaching a screen to the CAN FD bus in a similar way to how the PanelDue is attached via UART. That screen would need to have sufficient space for the UI (PanelDue like, 12864 like or otherwise) locally and then update is a method similar to the panel due (data from the the object model in one way or another).

I don't think tunneling SPI (or UART) over the CAN bus is the way to go.

Thanks for the input @T3P3Tony

o_lampe

@T3P3Tony said in Sammy C21 for display over CAN?:

I don't think tunneling SPI (or UART) over the CAN bus is the way to go.

@CNCModeller
I have a 1meter fibre glass adapter laying around with UART-converters (single direction only). IIRC it was also available as duplex converter.
The advantage is a very slim and flexible connection, but it would need battery power for the device.
Only worth it in noisy (EMI) environment or when the external device needs longer cable. (eg. CNC joystick)

oliof

I'd love to see an implementation of an Arduino or RPi Pico that drives an 12864 to the front while speaking PanelDue to the board in the back ... but I think that's a lot of effort for maybe 3 people using it.

dc42

@oliof it shouldn't be hard to port the PanelDue code to RP2040. We already have CoreN2G for RP2040 although it doesn't yet have the UART support.

However, as the RP2040 has so much more flash memory available, it could do more than the existing PanelDue does. I am working on a personal project that uses RP2040 + 5" display (the one that the non-integrated PanelDue used) + LVGL GUI library as the UI for a home energy management system. I'll publish it on my blog. However, I don't expect to make any more progress on it until after FormNext.