Hi,

I remember I have done a project almost 14 years back, to count the guests comming in and going out, so at end of the day, while closing the doors, gatekeeper should know that count should be zero, otherwise someone is still inside the building. It was used in a library and was very successful, as I used two LDRs with two light sources in frond of each LDR. It was not Infrared.

The basic principle was that if lights cuts to LDR-A while LDR-B was still expose to light then it would be up-count. And if light cuts to LDR-B whle LDR-A still expose to light then it would be down count. The only precaution I have taken is that IF both LDR get black-out then no count would be done. This was due to once a decision of up/down taken then reaching the object on second LDR would generate another pulse, so the truth table was..

LDR-A LDR-B Action taken
----- ------ ------------
high high No Action
high to low high up count
low high to low No Action
low to high low No Action
high low to high No Action

high high No action
high high to low Down count
High to low low No action
low low to high no action
low to high high no action.

if you see the above truthtable you can easily conculde that input data will be valid only when one LDR is transit from high to low while other LDR is high. It is simple AND/NAND function, but transition sensor is a task. I have used 74LS series up'down conter for that purpose.

you can translate the above as, up count is one direction and down count is another direction.

You use the two optocoupler used in mouse, and use the same gears and whole-wheel used in mouse. install both optocoupler on each side of wheel on 180degree on PCB. blank out all wholes on the wheel except two at around 90 degree. and connect this wheel mechanism to your motor by mechanical mean. and apply the above logic.
If wheel-whole keep passing on one direction, you will keep receiving pulses for one direction, if wheel-whole will passes in reverse direction you will recive the reverse pulses.

The above truth table can be achieved by simple gates electronic circuit or easily implemented with couple of 8051 IO lines and some easy code writing.

I could have solved these completely, but believe me I am very busy.

Rauf