Future Option for Linear Absolute Encoders

JoergS5

@neueklasse said in Future Option for Linear Absolute Encoders:

How to tell the Duet, (Duet3 btw) the actual Position from the ESP Board?

Duet has a very clever concept: it is controlled by G-Code commands completely. Everything from config.g to sliced 3D printing is based on it. So the ESP32 needs to send a G-Code command like a G92 to the Duet, that's it. You only need a connection between ESP and Duet which is supported by both. ESP and Duet support eg SPI, I2C, http, even TCP through WLAN if Duet supports Wifi. If Duet 3 is in the internal network, the ESP32 could send the data through WLAN and router to the Duet 3.

NeueKlasse

@joergs5, @PCR i think i like that way, i order an ESP to test it out!

JoergS5

@neueklasse said in Future Option for Linear Absolute Encoders:

work after a Restart it's 0 again (like i wrote the in the config fil

there was a thread recently how to store global variables:
https://forum.duet3d.com/topic/24880/does-rrf-have-maintenance-counters-timers

NeueKlasse

@joergs5 i tested that,

=> config.g = global ZAxisPos = 0
=> i created a "VariableBuffer.g" file in the sys Folder and Inside:
set global ZAxisPos = 0

then A Macrofile w.

M28 "0:/sys/VariableBuffer.g"
set global.ZAxisPos = -25
M29

After Calling the Macro the Variable inside the VariableBuffer.g file is Updated,
it's also persistent through a Restart.

if i set it under the M29 Command in the Macro: G92 Z{global.ZAxisPos}
the Z Value Remains 0

so i checked it in the Objekt Model Browser under "global" ... it remains 0.

JoergS5

@neueklasse I did not use and test it myself, I only saw the thread. If you have negative results, you could post your try and question in this thread where storing the variable was discussed.

NeueKlasse

@joergs5

the easiest way i think would be over UART, but in my case a PanelDue is connected on IO0,
do i have to Activate the SPI Protocol (M576) to send the Commands via the GPIO Header and
the SPI Pins?
I think the Second UART Port on IO1 is not working right now?

JoergS5

@neueklasse you don't need something fast or permanent for this task, so I would not waste a dedicated line, but use the Lan connection.*)

*) but there is https://github.com/technik-gegg/SMuFF-Ifc which could be used to be between Duet and Paneldue. But I2C is sensitive, I would prefer Lan.

If I remember correctly, you're using a Raspi with Octoprint also, so using Lan for all communication would be fine and usable for other ideas.

A different direction would be CAN-FD, with a board like Teensy 4 or Sammy-C21, or using the MCP2542FD chips. The Duet 3 is a groving environment with CAN-FD components, enlarging it with a component for encoder would be interesting. But this may require some development of the communication.

dc42

@neueklasse I've been looking at whether the forthcoming closed loop board could support this type of absolute encoder. It appears to me that it could, with a little extra hardware (possibly on a daughter board) to provide an RS422 interface. We would use BISS C protocol to communicate with the encoder.

NeueKlasse

@dc42 Thanks for the info, that would be great! i'm looking forward to the developments.
BISS C would be perfect (at least in my Case)

roiki11

@dc42

You could make a completely separate board with hardware quadrature counters or biss-c master ic(ic-haus makes them) then just use SPI to talk to them. The master ic supports SSI too.