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Detecting 7-Segment LED's With Phototransistors

L

Lasse Langwadt Christensen

Jan 1, 1970
0
Den tirsdag den 12. november 2013 01.24.31 UTC+1 skrev Jim Thompson:
Lose the google and the whitespace.

Maybe I need a filter that rejects on the basis of the ratio of
whitespace to total lines ?>:-}

I do wonder if google have hired "Mordac The Preventer"

seems like google is trying their very best to scare away
people by upgrading everything to new versions of useless

-Lasse
 
L

Lasse Langwadt Christensen

Jan 1, 1970
0
Den tirsdag den 12. november 2013 02.17.28 UTC+1 skrev John Fields:
---

The point is that I posted a picture - worth a thousand words - of a

perfectly valid hardware solution, while you code monkeys spew

thousands of words dictating how it should be done, but produce no

pictures.

most code is text

switch(abcdefg)
{
case 0x7E: digit = 0;break;
case 0x30: digit = 1;break;
case 0x6D: digit = 2;break;
case 0x79: digit = 3;break;
case 0x33: digit = 4;break;
case 0x5B: digit = 5;break;
case 0x5F: digit = 6;break;
case 0x70: digit = 7;break;
case 0x7F: digit = 8;break;
case 0x7B: digit = 9;break;
default:break;
}



-Lasse
 
J

Jasen Betts

Jan 1, 1970
0
Damn near any design can easily be "wrong" and that only evident
when it is actually applied to a real "display" (hopefully, the
characteristics of the display don't *change* over time or from
one unit to another).

just debounce it, if you get the same reading repeatedly for 100 ms it's probably good.
 
S

Spehro Pefhany

Jan 1, 1970
0
I do not see any monkey, but you are making one of yourself,
because I gave a link to my PIC asm code for analog video processing,.
I guess, even you, with help, could extend that code
to read segments,

You resolution is extremely limited anyway, because it will not be possible to implement
in many cases without lenses or even extremely small photocells.
Usually there is some glass or plastic in front of the displays,
so you could never get close enough to 'trigger' a single photocell, LDR, or whatever.
You NEED the camera,

Just for fun I was thinking if somebody would bet I can make it with an analog camera module and a PIC
in a month or 2 (weekend project), versus you a working one with your photo sensors in the same time,
And it should work with LCD displays and displays of any reasonable size too.

It is especially there (flexibility) that software wins.
And on component count, and maybe even on price, on market ability (yours needs a new design
for every display in existence?), and ease of installation.
:)

http://www.researchgate.net/publication/4245964_Reading_LCDLED_Displays_with_a_Camera_Cell_Phone



Best regards,
Spehro Pefhany
 
R

Roger Monroe

Jan 1, 1970
0
Hi All,

I'm tasked with logging into a PLC the temperature of a waterbath over time. Well, not exactly. The waterbath has a three character display that shows its temperature. Three 7-segment LED's would show, for example, 45.7
Any suggestions?

All help is appreciated,

Bart

UPDATE: I cheated and cracked open the waterbath this weekend and looked at the circuit board. As best I can see the numbers on the main chip are M430F4250 Rev A
The logo is sketchy, maybe looks like Texas.
I remember stumbling across 32Khz mentioned in a manual, and a mention of a programming port on the board (there is a vacant socket on the board). No other technical info in the waterbath manual, these terms were found in the alarm/troubleshooting section.
I've tried three different types of photo transistors/diodes and none react to the display (no milliamps/millivolts).

I wonder if I can access any information if in fact that is a programming port/socket.
I can get PIC's in Fairborn, Ohio and I can get Rasberry's in Springboro, Ohio, both places are somewhat local. How does the camera thing work? I snap a photo and then look at the binary of the file to interpret individual pixel color/location?
I'm willing to do the work, just need pointed in a good direction.
Thanks to all,
Bart
 
H

hamilton

Jan 1, 1970
0
UPDATE: I cheated and cracked open the waterbath this weekend and looked at the circuit board. As best I can see the numbers on the main chip are M430F4250 Rev A
The logo is sketchy, maybe looks like Texas.

Does the chip look like this:

http://www.ti.com/product/msp430f4250

Please post a pic of the board somewhere.

Thanks
I remember stumbling across 32Khz mentioned in a manual, and a mention of a programming port on the board (there is a vacant socket on the board). No other technical info in the waterbath manual, these terms were found in the alarm/troubleshooting section.
I've tried three different types of photo transistors/diodes and none react to the display (no milliamps/millivolts).

I wonder if I can access any information if in fact that is a programming port/socket.
I can get PIC's in Fairborn, Ohio and I can get Rasberry's in Springboro, Ohio,

Until you find out which chip is used, you may burn up your existing chip.

Why risk it ?



both places are somewhat local. How does the camera thing work? I snap a
photo and then look at the binary of the file to interpret individual
pixel color/location?
 
S

Spehro Pefhany

Jan 1, 1970
0
UPDATE: I cheated and cracked open the waterbath this weekend and looked at the circuit board. As best I can see the numbers on the main chip are M430F4250 Rev A
The logo is sketchy, maybe looks like Texas.

That's a MSP430F4250IDL (16-bit microcontroller in 48-pin SSOP package
with a 16-bit sigma-delta DAC on board). Datasheet here:
http://www.ti.com/lit/ds/symlink/msp430f4260.pdf

It won't do you much good, it's a custom programmed microcontroller,
no doubt with the code protected. You could erase it through the
programming port, but then you'd likely have to throw it away anyway
without the code to load in.
I remember stumbling across 32Khz mentioned in a manual, and a mention of a programming port on the board (there is a vacant socket on the board). No other technical info in the waterbath manual, these terms were found in the alarm/troubleshooting section.
I've tried three different types of photo transistors/diodes and none react to the display (no milliamps/millivolts).

I wonder if I can access any information if in fact that is a programming port/socket.
I can get PIC's in Fairborn, Ohio and I can get Rasberry's in Springboro, Ohio, both places are somewhat local. How does the camera thing work? I snap a photo and then look at the binary of the file to interpret individual pixel color/location?
I'm willing to do the work, just need pointed in a good direction.
Thanks to all,
Bart


Best regards,
Spehro Pefhany
 
R

Roger Monroe

Jan 1, 1970
0
Hi All,

I'm tasked with logging into a PLC the temperature of a waterbath over time. Well, not exactly. The waterbath has a three character display that shows its temperature. Three 7-segment LED's would show, for example, 45.7

I have a PLC that I have to log what the display shows. I cannot access the back of the display board to pickup any output.
Any suggestions?

All help is appreciated,

Bart

To everyone who's posted, THANKS! So much useful input, my gratitude to you..
Hey, let me run this by you. A mouse left button is probably just an open contact that I could hook two wires to and run them to one of the relay outputs on my PLC. I could then generate a mouse "click" any time I wanted. Before I incorporate a RasberryPi I could use my little netbook (Win7) with a USB camera (or IP camera) and hover my mouse over the "snapshot" button. Then the PLC would "click" at desired moments, saving image(s) for later manipulation. I don't want to dedicate my netbook for this, I would eventually use a Rasberry, I see some come as a camera kit.
Does this sound doable?
Thaanks again for everyone's time,
Bart
 
L

Lasse Langwadt Christensen

Jan 1, 1970
0
Den søndag den 17. november 2013 19.37.06 UTC+1 skrev Roger Monroe:
UPDATE: I cheated and cracked open the waterbath this weekend and looked at the circuit board. As best I can see the numbers on the main chip are M430F4250 Rev A

The logo is sketchy, maybe looks like Texas.

I remember stumbling across 32Khz mentioned in a manual, and a mention ofa programming port on the board (there is a vacant socket on the board). No other technical info in the waterbath manual, these terms were found in the alarm/troubleshooting section.

I've tried three different types of photo transistors/diodes and none react to the display (no milliamps/millivolts).



I wonder if I can access any information if in fact that is a programmingport/socket.

I can get PIC's in Fairborn, Ohio and I can get Rasberry's in Springboro,Ohio, both places are somewhat local. How does the camera thing work? I snap a photo and then look at the binary of the file to interpret individual pixel color/location?

I'm willing to do the work, just need pointed in a good direction.

Thanks to all,

Bart


how did you connect the photodiodes/transistors?

M430F4250 sound like a texas mcu,

considered a voltmeter(with some thing like rs232) in parallel with the
ADC on the micro ?


-Lasse
 
R

Roger Monroe

Jan 1, 1970
0
Hi All,

I'm tasked with logging into a PLC the temperature of a waterbath over time. Well, not exactly. The waterbath has a three character display that shows its temperature. Three 7-segment LED's would show, for example, 45.7

I have a PLC that I have to log what the display shows. I cannot access the back of the display board to pickup any output.

So my idea was to use several phototransistors (I've seen tiny ones) each strategically positioned on a segment of the displayed characters.
One guy suggested, instead of photodiodes, a webcam run through some OCR software, then the ascii transmitted to the PLC. Now THAT was thinking outside the box. Not really do-able in my situation.

Any suggestions?

All help is appreciated,

Bart

I just got some 475-3022-ND photo transistors from Digikey and actually saw them react to the green segmented LED display. However I've been playing with a Trendnet wireless IP camera which I can access with Internet Explorer. When connected, the webpage has a "snapshot" button and I took about 40 snapshots and they all look good and they all look the same. There was no partial segments from "refresh" frequencies of the LED's.
I took my mouse apart and found the left mouse button is a mechanical microswitch which I think I can splice into and run the wires to the relay output of the PLC.
Ah, progress. So much thanks to the group, hopefully someday I can donate something helpful.
Bart
 
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