Continue to Site

Welcome to our site!

Electro Tech is an online community (with over 170,000 members) who enjoy talking about and building electronic circuits, projects and gadgets. To participate you need to register. Registration is free. Click here to register now.

  • Welcome to our site! Electro Tech is an online community (with over 170,000 members) who enjoy talking about and building electronic circuits, projects and gadgets. To participate you need to register. Registration is free. Click here to register now.

interfacing ADC0808 with 89C51

Status
Not open for further replies.

mnoman

New Member
hello can any one tell me how to interface ADC0808 with 89C51 especially how to provide clock to the ADC and at what frequency
 
The clock frequency can be from 10KHz to 1200KHz, the interfacing depends on wheter you leave the ADC free-running or start it for each conversion(I prefer free-running). The clock freq is abt 10 higher than the sample rate (memory) and the EOC end of conversion output is used as an interrupt. I still have one of these around somewhere.
 
555s are using the same components that the free running osc on the 0808 would use and therefore contribute to complexity but add nothing.
 
Why not have the uP provide the clock? Seems like Timer2 with an output pin might be just the ticket.
 
**broken link removed** is a link to a site with ADC0804 code. Think of a 0808 as a 0804 with multiplexing. Search on 0804 & 8051 that generates lots of hits.
 
do any one have the code plz send it to me
as a free runninf ADC I am using the ckt from the link below plz check and let me know if it is the correct one

**broken link removed**
 
the Vref at 5V seems high and what signal are you using a varying DC? and the circuit still needs a clock of some sort.
**broken link removed** has code for 0808
**broken link removed** if you like C
 
Last edited by a moderator:
I am using clock from 555 IC using 388KHz freq i am using R1=4.7k R2= 10K and C=150pF is this ok where as the anlog input is from the LM35
 
Yes the spec shows anything between 10KHz 1200KHZ is OK, and for a test circuit like this, the input should be a DC voltage as an AC input would light most of the LEDs at some point. The idea of this circuit is to prove the 0808 is working, that's all.
 
ok I tested this circuit but some times all the outputs become high(logic 1) and somtimes some of them but i am not getting the correct result, any ideas
 
if you are using an AC(ie audio) this will occur try using a variable resistor between 0 and 5V as a dc source
 
I just tied one of the analog inputs to the +5V, then all outputs must be at logic 1 but this does not happens
 
Are you still using the test circuit, if so then all the LEDs except 1 should be light.
 
another ckt that i want to test is of a IR proximity sensor I actually want to have a distance of atleast 1m or 2m from the obstacle anyone having the idea plz help me
 
ur problem solved

mnoman said:
hello can any one tell me how to interface ADC0808 with 89C51 especially how to provide clock to the ADC and at what frequency
hi,
im ishank.first generate clock pulse as a output via 555timer on pin3 then connect it on pin10 of adc 0808.frequency should be max of 640 KHz .


GOOD LUCK:p
 
Hi,
im ishank.first generate clock pulse as a output via 555timer on pin3 then connect it on pin10 of adc 0808.frequency should be max of 640 KHz .
 
Status
Not open for further replies.

Latest threads

New Articles From Microcontroller Tips

Back
Top