Thanks PeterH for your answer.

I finally decided to do it "more standard": I will control the steps with the power amplifier/driver.
So the Controller CPU will only need to provide: pulse and direction.

We will design a pcb to control 5 motors with Accelstepper library. However not all motors will work interpolated (sync).

Hi all,

We've been designing a system based on Arduino to control CNC machines and more.
Actually I have the following doubt, and any suggestion will be greatly appreciated.

To control several CNC machines we have to give pulses to the servo motors and read the encoder position, however when we control several things at the same time, one CPU can't do all.
So we are designing a controller card.

The idea is the following:
1.- The master CPU gives the direction, acceleration, speed and pulses to the controller card (remember: several motors with at least 2 of them interpolated).
2.- The controller card gives the pulses to the servo-amplifier/motor.
3.- The quadrature encoder in the motor gives the pulses to an IC decoder.
4.- The IC decoder gives the pulses to the controller card which checks the position and acts according to that.
5.- When the position is reached the controller sends a signal to the master CPU, so the master CPU can send the next movement. If an error is produced the master CPU receives an error signal and all further movements are cancelled.

Doubts:
1.- How can I do it: One master CPU and several controller CPU's, or one master CPU and only one controller CPU. Doing only one controller CPU it's better because the communication process simplifies a lot: when you have to interpolate two axis all the process is done in only one CPU of the controller, so no delay with communications. But I'm afraid only one controller CPU will overhead, even that it is dedicated to this task and has a signal decoder.

I'm thinking to use ATMEGA328P IC's for the CPU, and for the decoder it can be a dedicated HCTL-2022 or an ATMEGA328P programmed only to decode the signal, however I don't know how fast can it be reading signals.

Any help will be greatly appreciated!

Yes I know Arm only designs the Ic's.
I've checked now and I found the SAM3X8C on RS, it chages the final character, but suppose it will be very similar.
RS ref. Nr. 769-2527

And it is even cheaper than ATMEGA2560!

So now the important point it Nr.2: Programming the Arm with the IDE.

Hi all,

First of all, I suppose this was already posted on the forum, but I didn't find nothing useful by searching. Sorry if I create a duplicated post.

Long story short:
I've designed my own arduino board based on ATMEGA1284P, so far so good.
But I needed more power to use TFT color displays with 800x600 or more resolution. So I am thinking on the Due.
However the standard Arduino Due board it's not suitable for me, it is very basic, un-isolated and so on, so I need to create a robust hardware.

The questions I have are:
1.- Is the Arm IC available for purchasing? I didn't saw it at RS.
2.- I want to upload the program via Arduino IDE, however it is not important if I have to do it with a programmer rather than and USB (because I understand that with the new IC the bootloader will not be there, no problem! (I do the same with the 1284p: I program it through an AVRISP).


Thanks so much for your time! Any clue will be greatly appreciated.

Muy buenas,

A finales de Enero tendremos hecho el primer prototipo de una de las 5 pcb en que consta el proyecto. Nuestra intención es hacer una pcb por mes, para acabar a finales de Mayo. Pero claro: dependera de lo que tardemos en afinar las versiones beta.

Como el coste se ha disparado, seguramente nos veais aparecer en kickstarter.com.
Por cierto, no se si lo comenté, al final el proyecto se llamará Workduino.com, cuando tenga tiempo ya haremos la web.

Ya daré más detalles cuando los tenga, y si veis que me olvido responder a este post, que estoy suscrito y recibo las contestaciones por mail.

Thank you so much Headroom,

So I2C is a good way to start. I asked this because maybe is there a more appropriated protocol. The communication is between pcb's, so there is no cables in between.

Hi all,

I am designing a system like a PLC where I need multiple ATmega to communicate each other, but I need more than one master as some of then needs to start the communication.

I see this is not possible over SPI. But I think for what I read that it is possible with I2C. The key thing is how can I accomplish this without having collisions or communication problems?

Thing to do is:
Case1: CPU1 wants to talk with CPU2, and starts the communication over I2C. NO PROBLEM.
Case2: CPU3 have some data to send to CPU1, tells over I2c that it has some data, and now CPU1 reads CPU3 over I2C.

It can't be done over I/O pins, not enough pins for the amount of CPU's! But it is all centralized over CPU1.
I know CPU1 can read over regular intervals all the other CPU's, but this is a lack of time, too slow and not optimal. As I am learning I want to find the right solution.


Thanks all!

Well, we have a lot of work to do yet, and the 7" is only a small part, so we didn't started yet.
The 7" screen is a part of a project we call "workduino" which is a scalable industrial controller half way PLC and CNC. We are designing now the first pcb board. I will open a post if someone is interested in it.

I had a look at the screen and UTFT, and the strange thing for me is that no power is supplied to the background, and all is 3.3v. Don't know if it is normal as I'm used to use alphanumeric and touch screen panels, which uses 5v or 24v.


I will try to find time and post it on projects section.

Thanks, I'll try to find a 7".

Any 7" display suggested for this library?

Thanks all for the answers.

We use the ATmega's for PLC and CNC machines, so all for industrial use. Code lines are normally +3000 lines and normally are ok, but problem can happen also on hardware side.

Either the way I need to double check if an error was made, and if it happens evaluate it and act accordingly.
To give you an example: Remember when on old windows 98 machines (I think also on newer ones) when you just suddenly plugged out the power connector and restarted the computer again the SO knew you didn't powered off correctly? This is done because when the SO boots up it stores the error in non-volatile storage, and when you power down the SO it set this to "0" again.
Same happens with machines, if something strange happens, as it is a partially blind system, you need don't know where the motors or others are positioned or if an operator hand is in between of the axis travel.

I don't want a watch-dog reset, I can't do that. I want a watch-dog that can evaluate an execute a program based on the reported error. Or at least a watch-dog that halts completely the system an prints an error message.
We also don't use any PC, it is an standalone system.

So I wanted to share my thoughts and recollect any better idea, because ideas distributed across several people work much much better.

Thanks to all!

Hi, I'm trying to do a reliable and programmable Watchdog (think of it as an Industrial Watchdog).

I arrived to the conclusion that the best way to do it, is to attach a second ATmega (that can serve also as a co-processor for other tasks) which waits for a signal on "X" pin every "X" seconds, if it doesn't receive it then it executes the desired operation: Reset, print a message, alarm, etc.
The same will do the principal processor, so this way I can detect if it's the co-processor down.

I was also thinking that depending on which part of the loop the program is, I can write a value to a variable (Ex. a byte value) so if the processor/program freeze at this part, I can also print the error message.


Is there any better way to implement this? What I'm looking for is reliability.

Maybe I am doing it the wrong way, but: Why you don't use millis() instead?

I mean, when you set led1 ON, you do:
digitalWrite(led1,HIGH);
time1=millis();

and for example if you want it ON for 250 ms:
if (millis>time1+250){
digitalWrite (led1,LOW);}

This way the loop it's never stopped.
NO?

Thanks doc_norway.

I got the SSD datashet and the TFT datasheet, I think modify the timing must be quite easy, but the ssd... I will do my best and let you know.

It must be not very difficult as far I can understand because the panel has the same resolution and chipset as one supported panel by UTFT but 7" instead of 5".

Will see...

Hi all,

I think I bought a very similar LCD with the SSD controller and 7" and same screen resolution... so I suppose I will get the same errors.

doc_norway: Is there anything I could do in the UTFT library to support this screen?