IJAZ AHMED wrote:
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And you are going to drive ALE with a signal of 469KHz. This corresponds to a time period of 2.13us. In this case, your ADC will see a change at its input at every 2.13 us while it requires 100 us to complete the conversion.

i,m not going to drive ALE with signals of 469KHz. this signals will be applied to the clock pin of ADC0809.
but ALE will tied with "OE" to +5V. this is one point

2nd point is that the "EOC" output is coupled to SC input, where falling edge of EOC output acts as SC input to direct the ADC to start the conversion
i mean As the conversion starts, EOC signal goes high. At next clock pulse EOC output again goes low, and hence SC is enabled to start the next conversion

in this mode i can use IN0 this can be done by connecting the address bits to the ground to have low active address as the three address bits are low, clear !!!!


BTW: If you are so short of port pins, how will you feed the multiplexer the address information (even if your idea works)?

i,m already using 8255.

the question of how to provide address bits remains un-answered.

in this case your right that is why i,m here to ask...

for three sensors i need:

IN0: 0 0 0 -------------->this cane be down through ground

IN1: 0 0 1

IN2: 0 1 0

i have seen this
http://www.8052.com/users/brunomarcio/
he has used Microcontroller: ATMEL AT89s8252 at 11.0592MHz

so if i cant use timer to generate clock signals for ALE/ address bits.
so can i use the same circuit with AT89C52. i,m using 8255 and i got 3 extra ports, i can use one of that for interface the output of this ADC circuit to the main circuit without any additional components between the two microcontrollers.???
i,m already using AT89C52 in the emulator circuit.
so is it possible to use another AT89C52 just to generate signals without return any digital data from 0809 to that MCU, infact i,m going to take that signals to the emulator circuit. is it pissible to do that.???

Regards
Albarkani