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Author Topic: 7 segment display panels for diesel motors  (Read 1460 times)
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Hi All,

Thank you for taking time to read this post and conmmenting.

Background
I have an old boat with twin diesel turbocharged motors that are pre-CAN. I am in the process of porting some sensors to each motor (thermocouples for coolant, turbo temperature, a nice stainless steel pressure sensor for the turbo inter-cooler pressure, and some hall sensors for engine RPM. I have machined up all the adapters to suit. That's it for the motors.

Although I have looked around extensively with Google, I can't find any Eagle files that suit my purpose for the display of this information, so I'll detail this project as clearly as I can. There are some commercially available units, but I like the idea of being able to pop out a dud display, or, change the colours easily, or mix them.


The project is all about displaying the information from the PORT and STARBOARD motors.  I intend to use RED 4 digit 7-segment displays for PORT motor info, and GREEN 4 digit 7-segment displays for the STARBOARD motor.
Each motor would have the following.
TASKDIGITSDIGIT SIZE (inch)
RPM4 1"
COOLANT Temp40.56"
Turbo Temp40.56"
Turbo Pressure40.56"
Oil Pressure40.56"

Preferred details
1. Design in Eagle CAD
2. Same PCB to suit both 0.56" and 1.0" (just plug in and solder whatever colour you like). Single PCB for each motor task (ie 5 individual PCB's for each motor)
3. Each PCB adressable (whatever chip suits + maybe DIP switches) and daisy-chainable.
4. PCB size no greater than 5cm x 2.5 cm (suits 2 up on a 5cm x 5cm for Seeed Studio PCB production.
5. No surface mount (hobbyist assembly for the old and blind smiley )
6. Discussion on the possibility of using an ATTINY....

If you're interested, please join in. Extension ideas and comments welcome.
Possible future extension would include 2 extra displays for diesel fuel flow. Some sensors are now down to a little over $US10!
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nr Bundaberg, Australia
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I think you could do this best with an AS1108 driver on each board, these can be daisy-chained so the hardware for each module is simple with no processor required.

Quote
Same PCB to suit both 0.56" and 1.0"
This might be tricky, probably OK but will need some research into displays to find some with pinouts that can co-exist like that.

Quote
Design in Eagle CAD
I'd rather chew my own arm off than use Eagle, but hey, that's just me smiley

Quote
Each PCB adressable
Not necessary in the normal sense of the word if you use chips like the AS1108, addressing is implied by the position in the daisy chain.

Quote
No surface mount
That's easy.

Quote
PCB size no greater than 5cm x 2.5 cm
I'm pretty sure 4x 1" displays will be larger than 50mm.

Quote
Discussion on the possibility of using an ATTINY
Sure, but what will the Tiny be doing?

_____
Rob



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Rob Gray aka the GRAYnomad www.robgray.com

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I suggest the MAX7219 or MAX7221

Each MAX7219/7221 can drive up to 8 digits of 7-segment display. They are easy to work with (SPI, 3-wire) and daisy-chainable. They also come in 24-pin DIP packages AND there is an automotive version available (which I think might suit you better than the regular version).

There is plenty of examples out there that uses the MAX7219 with Arduinos, driving either led matrices or 7-sd's



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I think you could do this best with an AS1108 driver on each board, these can be daisy-chained so the hardware for each module is simple with no processor required.

Thanks Rob. I looked at the datasheet and I guess it's similar to the MAX7219?? Any observations from those more learned as to which chip is better?
Quote
Same PCB to suit both 0.56" and 1.0"
This might be tricky, probably OK but will need some research into displays to find some with pinouts that can co-exist like that.

Yep, your're right. Min width for 1" is 24mm (x 4 = 100mm). There goes that one out the window....

Quote
Design in Eagle CAD
I'd rather chew my own arm off than use Eagle, but hey, that's just me smiley

Just had a quick learning experience with EC; I thought it was good. Any other suggestions?

Quote
Each PCB adressable
Not necessary in the normal sense of the word if you use chips like the AS1108, addressing is implied by the position in the daisy chain.

Agreed!

Quote
No surface mount
That's easy.
... smiley-cool...

Quote
PCB size no greater than 5cm x 2.5 cm
I'm pretty sure 4x 1" displays will be larger than 50mm.

See above!

Quote
Discussion on the possibility of using an ATTINY
Sure, but what will the Tiny be doing?

Seen some other tinkerers who basically simulate the MAX7219/AS1108 functions with an ATTINY. I guess it adds extensibility...

_____
Rob

Looked at you web page, and if you think you're grey mate, you could use my hair for headlights!


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I suggest the MAX7219 or MAX7221

Each MAX7219/7221 can drive up to 8 digits of 7-segment display. They are easy to work with (SPI, 3-wire) and daisy-chainable. They also come in 24-pin DIP packages AND there is an automotive version available (which I think might suit you better than the regular version).

There is plenty of examples out there that uses the MAX7219 with Arduinos, driving either led matrices or 7-sd's


Hi AlxDriodDev,
I was tending towards the MAX chip, but I like the comments from GrayNomad as well. Found this link this afternoon
http://dx.com/p/8-segment-led-display-board-module-for-arduino-147814
Too cheap to be true, and note that the 4 digit displays are mounted in machined headers making them removable, but, it still doesn't fit my requirements unless I do a re-think.

Does anybody know of a reliable supplier of red/green 4D7Seg displays?
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nr Bundaberg, Australia
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Quote
Min width for 1" is 24mm (x 4 = 100mm). There goes that one out the window....
Any reason you can't go to a larger board?

Quote
Just had a quick learning experience with EC; I thought it was good. Any other suggestions?
Not really, a lot of people are happy with Eagle, maybe you should learn that. There are a few free/cheap packages like DesignSpark etc but I don't know anything about them.

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if you think you're grey mate, you could use my hair for headlights!
I'm just planning ahead smiley

______
Rob
« Last Edit: May 24, 2013, 07:42:40 am by Graynomad » Logged

Rob Gray aka the GRAYnomad www.robgray.com

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Graynomad, thank you, mate! +1 karma for you!

I'll tell you why:
I have developed a patent-pending product that uses 10x MAX7219. The problem is that the MAX7219 is VERY expensive (even when bought in thousands). Until yesterday, I had no idea that there were direct replacements for it, until you posted about the AS1108. I went on to learn more about AMS and the AS11xx series and I found an IC that is a direct replacement for the MAX7219, the AS1100, and it costs less than half the price of the Maxim IC.

I had been looking high and low for that, and thanks to this thread and this post I found it. I've ordered a few samples from AMS and I'll report back when I get them and test them.

Thank you very much once more.

@petere10

I've bough stuff from DX for a long time and never had trouble with them. Actually most of the arduino-related stuff I have is from DX. They are that cheap. The only downside is that packages from them take forever to arrive, with a 30-35 days delivery time being quite normal.

Another suggestion I make to you is products based on the TM1638, specially this one. It has 8x 7segs + 8 bi-color leds + 8 buttons, everything controlled by a single TM1638, for which there are very good, working libraries for Arduino.


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