Timestamping data on data aquisition project

[Flamer1]

I've been working hard on a data aquisition system using a pic 16f877a and 16c765. External IC's samples an analog waveform and perform a/d. But, the samples aren't exactly evenly spaced to plot, so I need any help on an efficient way to time-stamp the data somehow. My knowledge of timers on PIC is limited too, please help

 

[Nigel Goodwin]

I've been working hard on a data aquisition system using a pic 16f877a and 16c765. External IC's samples an analog waveform and perform a/d. But, the samples aren't exactly evenly spaced to plot, so I need any help on an efficient way to time-stamp the data somehow. My knowledge of timers on PIC is limited too, please help

There are various 'clock' IC's available, most of which can be battery backed so they keep correct time even when power is off - by adding one of those you could accurately date and time stamp all readings.

 

[kinjalgp]

You can make use of I2C Real Time Clock IC like DS1307 : Cheap and easy way of implementing RTC in embedded systems.

 

[vik1501]

DS1307 is Real Time Clock IC with max. 1Hz squarewave output.

But then what is the time interval u need ? That will decide which clock to go for isn't it 8)

 

[Flamer1]

well the sampling rate is ~25kHz, so i would guess at least 1/25kHz = 40u sec

 

[kinjalgp]

Is you change the standard crystal (32.768 kHz) to 3.2768 MHz for DS1307, it is possible to achieve resolution of micro-seconds.

 

[kinjalgp]

DS1307 is Real Time Clock IC with max. 1Hz squarewave output.

But then what is the time interval u need ? That will decide which clock to go for isn't it 8)

1Hz is not the max. that you get at its output. According to the datasheet, 32.768 kHz can be achieved using 32.768 kHz crystal.