How to connect a light dependent resistor to a picaxe 28X1

the values does change when

the values does change when using a multimeter so the LDR is working.

I will try a smaller resistance to see if that helps.

i tryed using 3 different
i tryed using 3 different resistances and no result :frowning: i think i am cursed!!

try this

Try this.

 

  • Leave the 100K in place and replace the LDR with a 10K resistor -> check the reading.
  • replace the 10K resistor with 100K -> check the reading (should be 128)
if you still see no change then you must have the connections wrong.
Remember the 28X board input pins are (from the picaxe to the left side of the board) Ground, signal, V+.
Can you show a picture of the board with the LDR connected?

 

well actualy the manuel
well actualy the manuel calls for a 10K resistor not 100K, should I still fallow your testing methode?

its in the difference

The input pin is in between two resistors. one is fixed and the LDR is variable. They work as a voltage divider. If the two resistors are equal, the input pin should receive half the voltage of V+.

If V+ is the same voltage (say 5V) as the picaxe is receiving and the input pin is in between two equal resistors , you should read a value of 127 or 128.

Now change one of the resistors and the voltage is no longer divided equally and you should receive a different reading on the input.

You wont fry anything if you use 10K or 100K. If you connect the input directly to the ground you get a reading of 0 (zero) connect is directly to the V+ with any resistor (dont leave it out) you get a reading of 255.

if you still get a reading of 225 on the input pin when you connect the pin directly to ground then you are reading the wrong pin or the picaxe is broken.

Can you show a picture of
Can you show a picture of your connections to the board?

any updater on this? im
any updater on this? im planning to use the ldr on edge detection

Personally I never got it
Personally I never got it working, but you should try it for yourself.