IR detector

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- 16th August 2006, 17:00
geckogrotto

IR detector

Hi all I'm really new to picbasic and to electronics in general.
So please don't be too harsh on me.

I bought this
http://www.radioshack.com/product/in...entPage=search

Here is the back of the package should give more info
http://www.oscarcontrols.com/coinswitch/ledpd.jpg

What I want to do is basically start a timer when the beam is broken and count every time the beam is broken till its broken 100 times then report back the time.

Lets start with the basics.

So far I have 9V in to a 510 Ohm resistor to the IR led then to ground.
Across from that I have 9V to 10K resistor to the collector side and emitter side to ground.
(connecting a led in series I have been able to get the led to light when the beam is broken
What I'm not sure how to do is get a signal off the detector to a 16F628A input so when the beam is broken I can detect it.

Anyone offer any assistance?
- 16th August 2006, 17:21
BobK

Hello Geckogrotto,

Well you're almost there. First you will need to get a 5 volt regulator to drop your 9 volts down to 5 volts for the PIC. Then connect the 10K resistor between 5 volts and the collector of the phototransistor. You can then connect the junction of the 10K resistor and the collector to the input of your PIC. Your program should "see" a low (ground) condition when the "beam" is being detected and a high (5volts) when the beam is broken.

Hope this helps you!

BobK
- 16th August 2006, 17:27
geckogrotto

Thanks for the help Bob. Like I said im really new to electronics even but is there a way to use resistors instead of a voltage regulator?
- 16th August 2006, 17:43
geckogrotto

WOOT Thanks again Bob I dropped the voltage down to like 4.5V using 3AA batteries instead of a 9V, reduced the resistor on the LED and connected like you said... It works perfect! thanks :) I would like to know if there is a way with resistors to do the same thing and use a 9v if possible.
- 16th August 2006, 18:01
malc-c

You could use a 5.1v zenner diode to reduce the 9v down to 5v, but a small 5v regulator should be a better bet.
- 16th August 2006, 18:21
geckogrotto

I guess this is where I get confused with electronics.
I can take a 9V battery and use a resistor to run a 1.5V led without problem but I can't use a resistor the same way to run a 5V chip.

This seems to make sense to everyone but me lol

Ok on to the coding would this chip be able to handle the timer part of this or would I need a dedicated timer chip?

My guess is that there will be about 100 breaks in the beam in a 30 second time.

Currently I'm testing with this code and a led on RB1.
Main:
if PORTB.0 = 1 then
high PORTB.1
else
low PORTB.1
endif

Now that looks like it will work fine but, if the loop happens more than once before the bean is brought back it could count 10 times for every break...

Would this code work and only count once?

broken var byte
broken = 0
Main:
if PORTB.0 = 1 and broken = 0 then
broken = 1
high PORTB.1
else
low PORTB.1
endif
if PORTB.0 = 0 and broken = 1 then broken = 0

goto Main
- 16th August 2006, 19:01
peterdeco1

Hi geckogrotto. Try something like this.
START:
LET BROKEN = 0
LOW PORTB.1

Main:
IF PORTB.0 = 1 then ACTIVATE 'BEAM BROKEN
GOTO MAIN 'BEAM NOT BROKEN

ACTIVATE:
IF PORTB.0 = 1 THEN ACTIVATE 'WAIT FOR BEAM TO RETURN
LET BROKEN = BROKEN + 1
IF BROKEN >= 10 THEN LIGHTUP 'BEAM NEEDS TO BE BROKEN 10 TIMES
GOTO MAIN

LIGHTUP:
HIGH PORTB.1
GOTO LIGHTUP
- 16th August 2006, 19:12
geckogrotto

Thanks for your suggestion.

Can anyone tell me how to turn on a timer then turn it off and get the amount of time that was timed?
- 16th August 2006, 20:16
Archangel

Voltage divider

Hi, yes you can reduce the voltage to any set level you choose.
Using Ohm's Law
V. out = V in X (r2 / r1 + r2)

where r1 is the resistor closest to the power in
and r2 is the resistor closest to ground

Example v out = v in or 10 volts X r2, say 500 ohms . . . 5000
divided by r2 + r1, so if r1= 500 ohms you would get 1000 ohms,
so 5000 / 1000 = 5 volts. Simple huh? The problem here is if you lose the ground
foe even an instant then your input sees full supply voltage, also a voltage divider uses power all the time, in this example .01 amp.
OK the attachment didn't work so basicly two resistors in series, one end attached to + and the otherend to minus and you pull power from the connection in the center.
- 16th August 2006, 20:49
geckogrotto

Quote:

Originally Posted by Joe S.

Hi, yes you can reduce the voltage to any set level you choose.
Using Ohm's Law
V. out = V in X (r2 / r1 + r2)

where r1 is the resistor closest to the power in
and r2 is the resistor closest to ground

Example v out = v in or 10 volts X r2, say 500 ohms . . . 5000
divided by r2 + r1, so if r1= 500 ohms you would get 1000 ohms,
so 5000 / 1000 = 5 volts. Simple huh? The problem here is if you lose the ground
foe even an instant then your input sees full supply voltage, also a voltage divider uses power all the time, in this example .01 amp.
OK the attachment didn't work so basicly two resistors in series, one end attached to + and the otherend to minus and you pull power from the connection in the center.

Ok I don't think these actually exist but lets say they do.

If I had exactly 9V in and used
R2 950
R1 760
That would give me exactly 5V out?

About the connection what your saying is resistor to + and the other resistor connected to that and then to the negative and sandwiched in between the 2 would be my output of 5v?

Also if you want shoot me over the attachment to [email protected]

Thanks :)
- 16th August 2006, 22:47
Archangel

Yes

That is correct as would 400/500 (notice it adds up to 900) or any variant of above say 1200 /1500 12k/15k what changes as you go upscale is the circuit impeadance (the ability to load the circuit without significant loss of voltage).
If you only want to drive a PIC input pin and not light leds or run motors then use the larger (higher resistance) resistors, that way if you mess up your code and cause an input to become an output, set to low, you will not create a big short.
- 16th August 2006, 23:14
geckogrotto

Thanks again Joe.

Now I just need the most basic code I can find to start / stop the timer and get the results and I will be able to finish the rest.

I searched around the forums but I'm not sure how to implement the code with my chip.

There are internal timers right that you can turn on or off or am I thinking this whole thing wrong and I need to figure out how fast the chip is running then make my own count loop?
- 17th August 2006, 04:55
mister_e

one way in my mind now... Use HPWM on your led emitter, place the IR receiver on RA.4/T0CKI. Use Timer0 to count, Timer1 or Pause to do your sample time. The read the TMR0 register.

Another wich i don't really like but i saw many times... Led emitter directly to Battery via resistor, IR detector to RA.4/T0CKI. Jump in a interupt routine on a TMR0 overflow. Easy neat... may kill the IR Led soon.. battery too.

Do a search for T0CKI, you should find some tips to begin.
- 17th August 2006, 08:19
sayzer

1 Attachment(s)

Here is a table again to select a resistor value with respect to current (mA) vs input volt.
Make the rounding as close as possible.

--------

Code:

I(mA) R (ohm) R (ohm) 9V 12V 1 9000 12000 2 4500 6000 3 3000 4000 4 2250 3000 5 1800 2400 6 1500 2000 7 1286 1714 8 1125 1500 9 1000 1333 10 900 1200 11 818 1091 12 750 1000 13 692 923 14 643 857 15 600 800 16 563 750 17 529 706 18 500 667 19 474 632 20 450 600 21 429 571 22 409 545 23 391 522 24 375 500 25 360 480 26 346 462 27 333 444 28 321 429 29 310 414 30 300 400 31 290 387 32 281 375 33 273 364 34 265 353 35 257 343 36 250 333 37 243 324 38 237 316 39 231 308 40 225 300 41 220 293 42 214 286 43 209 279 44 205 273 45 200 267 46 196 261 47 191 255 48 188 250 49 184 245 50 180 240 51 176 235 52 173 231 53 170 226 54 167 222 55 164 218 56 161 214 57 158 211 58 155 207 59 153 203 60 150 200 61 148 197 62 145 194 63 143 190 64 141 188 65 138 185 66 136 182 67 134 179 68 132 176 69 130 174 70 129 171 71 127 169 72 125 167 73 123 164 74 122 162 75 120 160 76 118 158 77 117 156 78 115 154 79 114 152 80 113 150 81 111 148 82 110 146 83 108 145 84 107 143 85 106 141 86 105 140 87 103 138 88 102 136 89 101 135 90 100 133 91 99 132 92 98 130 93 97 129 94 96 128 95 95 126 96 94 125 97 93 124 98 92 122 99 91 121 100 90 120 101 89 119 102 88 118 103 87 117 104 87 115 105 86 114 106 85 113 107 84 112 108 83 111 109 83 110 110 82 109 111 81 108 112 80 107 113 80 106 114 79 105 115 78 104 116 78 103 117 77 103 118 76 102 119 76 101 120 75 100 121 74 99 122 74 98 123 73 98 124 73 97 125 72 96 126 71 95 127 71 94 128 70 94 129 70 93 130 69 92 131 69 92 132 68 91 133 68 90 134 67 90 135 67 89 136 66 88 137 66 88 138 65 87 139 65 86 140 64 86 141 64 85 142 63 85 143 63 84 144 63 83 145 62 83 146 62 82 147 61 82 148 61 81 149 60 81 150 60 80 Sayzer August'06 Selecting resistor value with respect to Current vs input Volt
- 17th August 2006, 17:04
geckogrotto

After some searching I found this
http://www.picbasic.co.uk/forum/showthread.php?t=190

after making some changes I think I will be able to use this to do what im needing.
- 20th August 2006, 01:17
geckogrotto

LCD Screen

Due to all the help I have gotten here I have everything worked out. I decided to buy a lcd screen so I could output the results to it but I have no idea how to hook it up.

LCD Display 16 characters with 2 rows LCD its Hitachi HD44780 compatible LSI controller

It has 16 pins.
1 GND Ground
2 +5v Power
3 Vcont Contrast voltage
4 RS Select
5 R/W Read/Write
6 EN Enable
7 DB0 Data bus
8-14 .......
15 LED K Backlight cathode
16 LED A Backlight anode

Ok 1 and 2 are pretty simple :)
Im not sure what pins I would hook up to my 16F628A chip. just data bus?
going to do some searching around to see what I can find was just so excited had to post :) Any help would be appreciated.
- 20th August 2006, 01:57
geckogrotto

Ok looks like mine is almost exactly like the olympic timer
http://www.picbasic.co.uk/forum/atta...4&d=1091819883

So it looks like 7-10 should be data..?

Man I still have so much to learn
- 20th August 2006, 09:20
mister_e

Quote:

I decided to buy a lcd screen so I could output the results to it but I have no idea how to hook it up.

Free schematic in PBP manual in the LCDOUT section.
- 20th August 2006, 21:10
geckogrotto

Quote:

Originally Posted by mister_e

Free schematic in PBP manual in the LCDOUT section.

Thanks lol
Good old fashion case of RTFM!

I have one questions about it tho, pin 3 on the lcd connects to the middle of the 20K resistor? I don't understand that part.

also I don't have a 20K resistor should I use 18K , 22K , 18K and 2K in series, or wait till I can get a 20K?

Thanks
- 20th August 2006, 22:10
mister_e

It's a 20K potentiometer or trimmer. It's there to adjust the LCD contrast. You can use lower value. 1-10K still work. You can also use two resistor to make a fix contrast. Wich value... ARRRGGH close to be impossible to tell, no lcd work the same way.

You can still use HPWM to make a software controlled LCD contrast... for now, just plug-it and display on it.
http://www.picbasic.co.uk/forum/show...light=contrast
- 21st August 2006, 01:34
geckogrotto

Got it :) thanks
- 21st August 2006, 20:32
geckogrotto

Ok last question :)

I have read all over about floating points and I still can't figure out how to do this.

My calculation is

shotspersecond = count / seconds
shotsperminute = shotspersecond * 60

with floating points this would work fine and tell me shots per minute avg.

Without FP if the seconds > count then I get 0 as shotspersecond and a number of other problems.

I know this can't be too hard but I can't seem to wrap my brain around it.

Any help would be very appriciated as once I get this I should be able to finish off my project.

Any help would be very appriciated as once I get this I should be able to finish off my project.

This is what I have so far... It may be accurate enough for what I am doing.
SPS = 5 / TotalTime
if sps = 0 then
SPS = 5 // TotalTime
SPM = sps * 60 / 100
else
SPM = SPS * 60
endif

Better way to do it?
- 21st August 2006, 21:04
SteveB

Quote:

My calculation is

shotspersecond = count / seconds

a) Declare your variables as WORDS

b) Multiply count by something like 100 or 1000. This shifts the decimal place to the right. Pick a multiplier that will keep the result below 65536.

b) Now, do the divide: shotspersecond = count / seconds.

c) Display shotspersecond with something like:

LCDOUT DEC shotspersecond/100, ".",DEC2 shotspersecond//100

The key is to shift the decimal place prior to the division, then adjust the display to account for the shift.

For more reading (and a better example of integer math), take a look at These threads from Darrel Taylor:
Retrieving 32bit Multiply Result
Retrieving Div32 Remainder
32-bit Variables and DIV32, Hourmeter 99999.9.

You might also try a search for integer math.

HTH,
Steve
- 21st August 2006, 21:12
geckogrotto

Ohhh thanks Steve I was multiplying x 100 after the divide not before :) thanks I got it now :)
- 24th August 2006, 20:11
geckogrotto

Ok really this time last question. This has more to do with eagle but figured you guys would know.
I'm trying to find a LCD like the one on page 94 in the manual to use with eagle and I can't seem to find one.

I downloaded all the LBR files I could find that said LCD on them but still no luck.
- 25th August 2006, 00:27
malc-c

Mat,

Just select one of the connectors / Pin Headers that suit the number of connections on the LCD. This will allow you to either plug the LCD into your board if you use a suitable pin and header block, or solder wires directly to the pads if the LCD is remote from the board
- 25th August 2006, 01:05
geckogrotto

Thanks malc that will work fine.
For anyone who was interested or helped with the process and wanted to see the end result here is a video.

http://www.gecko-grotto.com/workshop/lcd_counter.wmv
- 30th August 2006, 01:14
emavil

Infra Red Detection in PICBAsic

Hi, i'm building a simple remote controlled project consisting of 8 12v Relays. I'm using TSOP1738 IR receiver from Vishay Telefunken. I'm using PIC16F84A microcontroller and PICBasic Compiler. I got it from a junked VCD player. Is there anyone who knows how to intercept the coded signal from any IR transmitter? How do i control individual relays independently.
- 30th August 2006, 03:16
mister_e

look at those links
http://rentron.com/PicBasic1.htm
http://rentron.com/remote.htm
http://www.winpicprog.co.uk/pic_tutorial5.htm
Enjoy and good luck!