Looking for driver to compensate 64-256 LDR inputs

[dnhuruag]

using 74LS573 8-bit latch 3 state with 64-256 inputs LDR? is it possible? is their any driver that can compensate the 64-256 inputs to PIC which is only an 8 bit in every ports? i would be greatful any means of help... is there any alternative solution? please help...

 

[mcs51mc]

pcf8575 input pic

74LS573 is a digital IC <-> LDR is analog componenten!
What do you think?

What do you mean by 64-256 inputs LDR??
Do you need a light meter based on an LDR??
Do you to read the LDR value with an analog input of a PIC??

You see more questions than you to answer your post

 

[dnhuruag]

ldr et pic

ahh... thanks for the reply... the 64-256 LDR is an input module to the PIC an is used in my project as a matrix. my project was to create a marksmanship training system. using a laser pointer to trigger each of these LDR's. let us say 64 inputs of LDR so my matrix would be an 8x8 matrix... how do i configure each of these LDR so that the PIC can recognize if one of these LDR's has triggered. moreover, if one of these LDR triggers the LCD would display the coordinates corresponding to the triggered LDR. e.i. X1, Y5 --> display of the matrix if triggered... can i use a latch? or a buffer perhaps? or do i need to convert the output value of these LDR to digital form so that the PIC could read?

 

[IanP]

ldr as analog input

Because you need only Light-On or Light-Off information, conversion of LDR signal can be very simple .. see picture below ..
After conversion, these signals can be used with any digital inputs, for example, 573 latches ..
Another thing to consider are I2C port expanders with interrupt (PCF8574 - 8 I/Os, PCF8575 - 16 I/Os, and so on ..) which may save you a lot of PIC's pins, as dozens of them can be easily controlled using ony two control lines: SCK (clock) and SDA (data) ..
See:
https://focus.ti.com/docs/prod/folders/print/pcf8575.html

Regards,
IanP

 

[dnhuruag]

ldr laser pointer

ahh... so thats how it goes... thanks... what if after conversion of the LDR to digital form, it's output will be connected to a 573 latches since a 573 can only accomodate 8 bits of data so i will be using 8 latches for my matrix of 8x8 and then connected to PORTD of PIC16F877 using a 74LS138 a 3 to 8 demux decoder to scan and select/unselect, if these eight 573 latches has a logic 1(one of the LDR has triggered). Is it a nice or bad idea?

best regards,
dnhuruag

 

[IanP]

74ls138 3:8 decoder

Reading 8 x 74LS573 in a sequence is a good idea ..
Another matter is how you are going to do it - using 8 PIC's pins or 3 pins plus 74LS138 ..
Both ideas should work, however, if you have enough µC pins available - just use them ..

Regards,
IanP

 

[dnhuruag]

ldr+pic

ahhh... ok... thank you very much, now i have an idea on how to work with it... i will be using a MicroC compiler for the PIC... if you have any suggestions about my project then i would be glad to hear them from you...


regards,
dnhuruag

 

[blueroomelectronics]

light meter with an ldr

IMHO I would have approached it backwards, the target consists of LEDs and the gun has the sensor. Just like the old video games. Easier and cheaper as the LEDs can be modulated digitally and synchronized to the guns sensor.

 

[dnhuruag]

Re: 64-256 LDR inputs

i am not using LED's, instead an LDR(light depenent resistor) in my matrix using a laser pointer as a triggering device...