IR detector

[geckogrotto]

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


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?

[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

[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?

[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.

[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.

[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

[geckogrotto]

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.

[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

[mister_e]

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.

[geckogrotto]

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

[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

[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?

[SteveB]

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

[geckogrotto]

Ohhh thanks Steve I was multiplying x 100 after the divide not before thanks I got it now

[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.

[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

[emavil]

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.

[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!