Intercommunication between two or more megaAvrs

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clawson wrote:

You need a solution where you can have multiple devices connected.


Is there any solution for this?

Salman

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Brian Fairchild wrote:

The OP could, for example and by way of a learning exercise, have a separate AVR for each character of the display and a 'master' AVR which does the actual timing. Each display AVR has their RXD lines connected together and to the masters TXD line. No other interconnect is needed as there is no need for the displays to talk back to the master. Every second the master could transmit the time and date as a simple 8 byte string (start character + Y,Y,M,D,H,M,S). Each slave would be responsible by extracting the byte it needs from the string and updating its connected display.

 

It's not an efficient way to do it and it's not how most of us would do it but it is a way.


This Is what I wanna do.
Efficient way?

Salman

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Sorry for being vague

In a nutshell.I will explain about my project.Note I'm asking solution for intercommunication
Well
I didn't post this before because it is sensitive issue and it is related to religion which many don't like or don't know much about it
Well I attached one image which I wanna make.
Don't be confused.
There is time and date on it,
According to time and data,other things are based
Such as fajr,zuhr,...etc...
Again I'm only asking about intercommunication.
Thanks

Attachment(s): 

Salman

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Just give a rough idea.
Anything wrong with post?
Waiting for reply

Salman

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Still don't understand why that would take more than one micro? If there's only one there's no need for external comms (just internal signals passed from one module to another)

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This display driving came up in another thread....  Why use multiple AVR's when you can use two of these:

 

http://www.ebay.com/itm/MAX7219-...

 

and an SPI bus?  Now the OP can display the Months, and anything else without the need for writing code for several AVR's and the comms between.

 

JIm

I would rather attempt something great and fail, than attempt nothing and succeed - Fortune Cookie

 

"The critical shortage here is not stuff, but time." - Johan Ekdahl

 

"Step N is required before you can do step N+1!" - ka7ehk

 

"If you want a career with a known path - become an undertaker. Dead people don't sue!" - Kartman

"Why is there a "Highway to Hell" and only a "Stairway to Heaven"? A prediction of the expected traffic load?"  - Lee "theusch"

 

Speak sweetly. It makes your words easier to digest when at a later date you have to eat them ;-)  - Source Unknown

Please Read: Code-of-Conduct

Atmel Studio6.2/AS7, DipTrace, Quartus, MPLAB, RSLogix user

Last Edited: Fri. Mar 31, 2017 - 05:22 PM
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What is your definition of "efficient"? Low cost? Low power consumption? Low bits per display "frame"? No physical wiring? Long distance? 

 

And, what do you mean by "Digital using decoders"? Every digital signal is encoded and decoded. Most transmission methods are serial so, at the very least, you encode parallel into serial (eg, shift register) and decode serial into parallel (another shift register) - that is what a UART does, inherently. That is what happens in SPI and I2C. But, serial data can be further encoded (AFSK, like Bell-202 tones) or  DTMF tones, for example, with corresponding decoding.

 

So, you really need to  give us more  details about your question. 

 

Jim

Jim Wagner Oregon Research Electronics, Consulting Div. Tangent, OR, USA http://www.orelectronics.net

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In reply no. 54, i clearly stated everything.I request you all to check it out.

 

 

 

so do u think that i really need one uc?

remember 365 days thread.it was about sunrise and sunset.

here are some additional 6 or 7 things like that .which are tracked over year

//code for yearly management of these variables

//controlling displays using led drivers according to management

note:im asking solution for intercommunication

 

 

ka7ehk wrote:

What is your definition of "efficient"? Low cost? Low power consumption? Low bits per display "frame"? No physical wiring? Long distance? 

 

And, what do you mean by "Digital using decoders"? Every digital signal is encoded and decoded. Most transmission methods are serial so, at the very least, you encode parallel into serial (eg, shift register) and decode serial into parallel (another shift register) - that is what a UART does, inherently. That is what happens in SPI and I2C. But, serial data can be further encoded (AFSK, like Bell-202 tones) or  DTMF tones, for example, with corresponding decoding.

 

So, you really need to  give us more  details about your question. 

 

Jim

i generally thought about digital using decoders in starting,after i got to know all these interfaces.

whatever is listed side to "efficient" -i want possible ones.

sorry if im still vague

Salman

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The OP sure has no problem DEMANDING that we reply:

salmanma6 wrote:
Waiting for reply

 

And the like, but then gets pissy when another question comes up on this project:

salmanma6 wrote:
In reply no. 54, i clearly stated everything.

 

What the OP does not seem to say is what has the OP done to date other than a Google search that did not give the results they liked.

 

Salmanma, there are over 59 posts in this thread alone and nothing has been accomplished other than to show you have little to no idea what you want to do other than make a really ornate clock, or how to do it.  there are a few posts where some explanation is given but no one wants to have to weed through 50_ posts to get the idea.  Hence repeat questions.

 

I would suggest at this point that you take a few moments and write down on paper EXACTLY what you want to accomplish and the functions involved in the project.  Include the specifications of the display(s) and any other peripherals you think you may need.  Once you have this spec laid out, POST IT HERE so we can all get the idea.

 

Otherwise this thread is going to spiral further into the abyss it has already slipped into.

 

JIm

I would rather attempt something great and fail, than attempt nothing and succeed - Fortune Cookie

 

"The critical shortage here is not stuff, but time." - Johan Ekdahl

 

"Step N is required before you can do step N+1!" - ka7ehk

 

"If you want a career with a known path - become an undertaker. Dead people don't sue!" - Kartman

"Why is there a "Highway to Hell" and only a "Stairway to Heaven"? A prediction of the expected traffic load?"  - Lee "theusch"

 

Speak sweetly. It makes your words easier to digest when at a later date you have to eat them ;-)  - Source Unknown

Please Read: Code-of-Conduct

Atmel Studio6.2/AS7, DipTrace, Quartus, MPLAB, RSLogix user

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What jgm (East Coast Jim) is talking about is a "system specification". It MIGHT include statements like: "up to 5 displays are required in locations separated by up to 30m from a master". Another possible statement is something like "this device is a clock that shows prayer times adjusted for day of year". Another might be "there will be one display which might or might not be at the same location of the timekeeping function".  Another possible one is that "the display must be visible in the dark without the viewer having to change anything".

 

Do not worry about details like "multiplexing" or communication methods or even look-up tables. Those come, later, as a natural consequence of the system design. 

 

This is NOT a criticism. I often get caught up in a technical idea to solve a problem, only to find that the problem really is not a problem, after all. Solving this starts with a clear statement of the system specification. This is just a fancy name for "Describing what you want the 'thing' do to do" rather than "How to do it".

 

<edit>Personal Opinion: You do not need to be concerned that this has a religious use. It is not a debate about religion ideas. It is about creating technology to meet the requirements of a particular religion. It is no worse (or better) than the little solar powered (electric) Buddhist prayer wheel that my wife has. It serves a purpose that can be "solved" technically. I think that most of us, if not everyone, have very little problem with that. </edit>

 

Jim (West Coast Jim)

Jim Wagner Oregon Research Electronics, Consulting Div. Tangent, OR, USA http://www.orelectronics.net

Last Edited: Sat. Apr 1, 2017 - 03:50 AM
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Spec of project

1)it showcases prayer timings(which vary day to day) ,events:Period of time ex:Fajr,zuhr.etc..\present and next event,current time,date,month,day.

2)Time source is rtc and gps module for precise timing.

3)It will be powered by mains.if there is no power it will work on rechargable battery

4)Setup will be mounted on wall

5) Poster size 72” L x 35” Ht
Frame size 75” L x 38” Ht
Packing box 80” x 43” x 6”
Weight 29 Kg + 5 Kg Battery

6) i will be using 

17 led matrix modules(8×5)(made on my own with normal leds)(White)

    84 no of 7segment displays of voltage req-3v(between 25mm to 40 mm) and four 7 segment displays of voltage req(7-8v)(between90,mm to 100mm )  (APPROX)(White)

7)i have some alerts like producing a beep sound when its time to pray.

8)I will be using remote to set some timings 

 

Salman

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Remember - this is YOUR project, so we're not going to design it for you.
It is not unreasonable to have a microprocessor for each group of displays and one to compute all the time values. This creates two challenges:
1. Driving the leds
2. Communications.

There are plenty of examples how to do the above on the internet. Solve one problem at a time. You really don't need to look much further than Arduino for ideas.

Once you've solved those two problems, this will give you a basis by which to solve the other problems. One by one you should move closer to completion.

For the moment there is no need for you to ask more questions - start doing your research and start building prototypes. You should only need to come back here when you have a specific question.

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This is good start. I think that your weight estimate may be a bit too small because just the circuit boards for the large matrix modules will be fairly heavy. But, that is not terribly important, yet.

 

what kind of "remote" do you want to use? 

 

Your description of the display is NOT very clear. How many "digits"? What sizes are the digits?

 

Jim

Jim Wagner Oregon Research Electronics, Consulting Div. Tangent, OR, USA http://www.orelectronics.net

Last Edited: Sat. Apr 1, 2017 - 06:59 PM
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IR remote
4 digits +some are 40mm(other) +100mm(Main current time)

Salman

Last Edited: Sat. Apr 1, 2017 - 07:06 PM
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How many TOTAL digits in the display? And how many of each size? Can you give me a name for each group of digits? Also, you refer to 8x5 digits and also 7-segment. These are not equivalent. Do you use one style some places and the other style in different places?

 

Jim

Jim Wagner Oregon Research Electronics, Consulting Div. Tangent, OR, USA http://www.orelectronics.net

Last Edited: Sat. Apr 1, 2017 - 07:23 PM
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If this were my project I would...

 

1) Make two 'display' PCBs, one for each size of display you anticipate. ie one for your 25-40mm display and one for you 90-100mm display. Each PCB would hold the maximum number of digits you need for each position with holes left empty if you need less digits/letters. Each PCB would have a MAX7219 on it.

 

2) Make a 'control' PCB with just one AVR on it along with the RTC chip and the interface to the GPS module.

 

3) Buy a commercial GPS module.

 

Design considerations...

 

*) The communications from the control PCB to the displays only needs to be one way. The displays do not need to talk back to the controller. This communications channel does not need to be fast. The MAX7219 has a dataout pin for daisy chaining. I would use SPI for this.

 

*) The GPS module is likely to need a USART port.

 

*) The RTC chip is likely to need an I2C port.

 

So you need an AVR with one SPI port, one USART and one I2C port.

 

That's it. It's not a difficult project.

 

If the MAX7219 is difficult to get in your location, or is expensive, then you could replace it with a small microcontroller and a few transistors. The microcontroller would handle the display multiplexing and listen on its SPI port for commands. You could even emulate the '7219 commands.

#1 This forum helps those that help themselves

#2 All grounds are not created equal

#3 How have you proved that your chip is running at xxMHz?

#4 "If you think you need floating point to solve the problem then you don't understand the problem. If you really do need floating point then you have a problem you do not understand." - Heater's ex-boss

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7sg-7segment displays.

In the image i wrote  4-4lvl-7sg

                 first indicates no of displays

                 second indicates the level here i mean level4 =40mm and level2=100mm

                 third indicates type of display.

I have the following names for group of digits and also ill specify no of digits.

         Name            no of digits/characters       Type of display

  1. ​Sehri                  4                                 7sg
  2. Iftar                    4                                7sg
  3. Zawal                  4                                 7sg
  4. Fajr-Azaan           4                                 7sg 
  5. Fajr-Jamaat          4                                 7sg
  6. Zuhr-Azaan          4                                 7sg
  7. Zuhr-Jamaat         4                                 7sg
  8. Asar-Azaan            4                                 7sg
  9. Asar-Jamaat           4                                 7sg
  10. Maghrib-Azaan         4                                 7sg
  11. Maghrib-Jammat      4                                 7sg
  12. Isha-Azaan              4                                 7sg
  13. Isha-Jamaat             4                                 7sg
  14. Juma-Azaan             4                                 7sg
  15. Juma-Jamaat           4                                 7sg
  16.  Present time            4                                 7sg
  17. Present event           4                                 Led matrix
  18. Start                          4                                 7sg
  19. End                             4                                 7sg
  20. Date                           2                                 7sg
  21. Day                             3                               ledmatrix
  22. Month                         10                              ledmatrix
  23. Year                             4                                 7sg
  24. Sunset                          4                                 7sg
  25. Sunrise                           4                                 7sg

From 4 to 15 ,they are dependent on user.so no need of intercommunication.Just user has to set some digits.

Other vary from day to day,time to time

Here are the specified locations .

 

 

 

 

 

 

Salman

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Thank you sir .smiley

Salman

Last Edited: Sun. Apr 2, 2017 - 05:20 PM
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Thank you sir.smiley

Salman

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OK, I will have something for you in a few hours based on that. It will show you how I would turn this information into a "system specification".

 

Jim

Jim Wagner Oregon Research Electronics, Consulting Div. Tangent, OR, USA http://www.orelectronics.net

Last Edited: Sun. Apr 2, 2017 - 09:11 PM

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