LinuxCNC EMC Port to FreeRTOS? Curious...

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07 Mar 2024 03:27 #295374 by Mecanix
For an application that requires serious timing integrity, let's just say that freeRTos ain't exactly your best friend. So errant it even has its own catchupticks() api if I recall correctly. Top of its class to fire up lcd panels, BLE scans and connections and/or flash christmas lights though... and everything else that isn't highly dependent of a precision tick...

Have your crystals temperature calibrated upfront for sure! ~Watchdog
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07 Mar 2024 09:30 - 07 Mar 2024 09:44 #295381 by wez
RPI5 is decent, such an improvement. Fully agree though. Running a dedicated lowish-cost x86/x64 machine is better and they are everywhere. I used a RPI4 as a showcase demo as prior quick example simply because it was setup and ready to roll, that is all.

The xTaskCatchUpTicks it's quite a specific use-case generally implemented for when interrupts are disabled for extended periods, such as, during extended writes to flash. It's a specific use-case. TCXOs all the way.

Shall we not bother getting into the weeds around timing of an RTOS - is there really any point?

What's there to gain other than having a pissing match? I didn't come into here saying "FreeRTOS is a gimmick". It's just impolite and outright rude to gain a rise.

rodw - thank you I appreciate your feedback!

EDIT: tommylight - IIRC there's been a couple few RTOS's for windows. RTX springs to mind - long time ago. Is it still going? Currently from MS there's Azure RTOS ThreadX. There's even ports for FreeRTOS for windows but aimed at development.
Last edit: 07 Mar 2024 09:44 by wez.
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07 Mar 2024 11:09 #295391 by tommylight
Rant:
I like microcontrollers, they are meant to do a job and they do it very good, and for the price astonishingly reliable!
RPI was a case of "expecting to much from to little", it is overpowered to be a microcontroller but to weak to be a PC. It does have it's uses though, granted expectations are kept in check.
Youtuber BitLuni did awesome stuff with ESP32 and VGA outputs from it.
And about 3 weeks back i fixed a huge industrial plasma machine running on a single processor at 280MHz! Now using an ESP32 for motion control and another for video output might ...
:)
End rant.
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07 Mar 2024 11:40 #295394 by cornholio
I say go for it.

It really wont affect users who want to use Linuxcnc on a x86_amd64 or arm64 platform.

What would be interesting, is using the LPC bus that is exposed on the TPM connector.
Apparently there's a demo here, but no code as of yet.
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07 Mar 2024 12:45 - 07 Mar 2024 12:48 #295402 by wez
tommlight - re the VGA on the ESP32. Another shameless plug...

This is essentially what BitLuni did but on steroids....

800x480 resolution at 16bit colour and 30fps. Potato camera - but it's a high pixel density display - not "retina" levels but far far superior than the low cost SPI displays. Single core. Capacitive multi-touch. All done in ESP32-S2 hardware (DMA buffers). Oh MicroPython on top of all that too.

STM32 has the features in their STM32F746 and STM32F469 hardware but cost is considerably more (20x pretty much).





EDIT: The tearing you see is actually LVGL not flushing to the buffer fast enough when generated each tab since they are rendered from templates on the fly! A fully dynamic UI.
 
Last edit: 07 Mar 2024 12:48 by wez.
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07 Mar 2024 12:46 - 07 Mar 2024 12:47 #295404 by Mecanix
You'll have to pardon my grumpy attitude toward anything that sits above or between ticks nowadays, Wez. I've been like that ever since our great 'innovators' virtualized and cached everything that had real-time potential. RT is some epic stuff from the past... should be renamed to WF to eradicate the confusion. As in "WAIT FOR™".

Much like Tommy though, huge (hugeee) user of those micros (esp,stm), I have them everywhere already otherwise. 

 
Last edit: 07 Mar 2024 12:47 by Mecanix.
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07 Mar 2024 12:49 #295405 by wez
No worries at all man :) I do fully understand where you are coming from. If I came across as arrogant - I am sorry, truly not intended!
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