Dear All, following is the code is not working..can any please guide me where is the problem.. #include<reg51.h> sbit ale=P1^0; //address latch enable sbit oe=P1^3; //output enable sbit sc=P1^1; //start conversion sbit eoc=P1^2; //end of conversion sbit clk=P1^7; // clock
sbit ADD_A=P1^4; // Address pins for selecting input channels. sbit ADD_B=P1^5; sbit ADD_C=P1^6; sfr input_port=0x80; sfr output_port=0xA0;
void timer0() interrupt 1 // Function to generate clock of frequency 500KHZ using Timer 0 interrupt. { clk=~clk; }
void delay(unsigned int count) // Function to provide time delay in msec. { int i,j; for(i=0;i<count;i++) for(j=0;j<1275;j++); }
void main() { eoc=1; input_port=0xFF; ale=0; oe=0; sc=0; TMOD=0x22; //timer0 setting for generating clock of 500KHz using interrupt enable mode. TH0=0xFD; IE=0x82; TR0=1; while(1) { ADD_C=0; // Selecting input channel 2 using address lines ADD_B=0; ADD_A=1; delay(2); ale=1; delay(2); sc=1; delay(1); ale=0; delay(1); sc=0; while(eoc==1); while(eoc==0); oe=1; output_port=input_port; delay(2); oe=0; } }
You have an interrrupt that is intended to run with 500kHz frequency. Is your processor even fast enough to manage 0.5 million interrupts / second - remember that every interrupt consumes several instructions.
Why don't you use a timer to create the 1ms delay? Don't you realize that the delay time of a software loop is affected by the percentage of CPU capacity that is consumed by interrupts?
By the way - where is the source code? You don't have anything tagged as code in your post - didn't you notice the information about how to post source code?
What is wrong? You haven't exactly spent much time explaining your troubles. Just a subject line "ADC0808 output is not stable". Nothing about exactly what happens and what things you have done to try to figure out what is wrong.
Dear Sir, i m getting unexpected values on D0-D7(outputs) of ADC,even if my input analog is stable which is 0 to 5 volt and Ref. voltage is +5Volt..i m trying to solve this problem from last one week but i m getting unstable values from the mentioned code...pls help me... if u have any source code to operate successfully ADC0808 then pls provide me ..it is very very very urgent....
Further, my requirment is simple..i want to run at89s8253/52 MCU with ADC0808 and i m giving 500KHz pulses as clock to ADC ..If any have code for such hardware (AT89s8253,crystal 11.0592MHz and ADC0808) then pls pls send me...i m fed up from one week ..
IF the "unexpected values" are coming from the outputs of the ADC then, surely, it's nothing to do with the 8051 or the code running on it?
What have you been doing in that week?
www.lmgtfy.com
www.national.com/.../ADC0808.html
Have you checked that the 500kHz clock is accurate & stable?
Have you checked that the analogue input to the ADC is stable? Obviously, if you have glitches on the analogue input, then you are going to get glitches in the digital output!
Did you even READ the comments above? Do you really understand what your code does? Do you understand that this is a MUST in order for _your_ code to work? Now, take a deep breath and explain, SLOWLY and clearly, exactly what the problem is and what you have done so far.
Yes, i read but i have data sheet for adc, and the first link i did not understand what was that? As per code: there is no problem in that code? is there any way to generate 500KHz pulses from MCU AT89s8253? or pls suggest me any code to achieve this stuff...pls. pls. pls
Are you saying that you haven't even checked if you do get a 500kHz signal generated from your ISR? You are not doing any debugging at all - just moving the responsibility for thinking to "the net"?
Why haven't you bothered to return with real responses to my initial post?
By the way - some 8051 timers can be used to directly toggle an external pin, allowing programmable square wave output without any ISR that performs the toggling.
what r that toggle routine of timers can u guide me ?
No, I can not guide you.
I did say _some_ 8051 timers can toggle pins.
I don't know if you have any timers that do support this. But you should be able to figure this out since you can read datasheets and knows what chip you have.
"what r that toggle routine of timers can u guide me ?"
Study the Datasheet for your 8051 chip!
what r that toggle routine of timers can u guide me ? maybe micro (u) can guide you as to what resist (r) that toggle routine
my requirment is simple
LOL, how did YOU determine that?
"maybe micro (u) can guide you as to what resist (r) that toggle routine" pls explain..i didnot get u.
'u' is the symbol for "micro"
Why do you keep putting "micro" in your sentences?
Is it really too hard for you to write "you" ?