Pic18f452 - Electronic Circuits Projects Diagrams Free

yantheman · 4th May 2006, 05:16 AM

Im using PIC18F452, ADXL203 and the given microchip target board. Im trying to read the 2 analog output of the accelerometer and do a ADC and display the digital value on an LCD. The connection is as shown in the attachment. Just checking is the connection correct? Anything missing ? Is my analog input correct as someone pointed to me that RE port cannot be used.

Oznog · 4th May 2006, 05:17 PM

Yeah, I believe all the analog inputs are on PortA. Check your spec sheet.

The output impedance of the ADXL devices is 32k ohms, at least the ones I know. That is FAR too high to provide to a PIC which needs 2.5k ohms max to live up to its full specifications.
Also the ADXL devices need to be band-limited. Simply put a cap on the output, the cap will make an RC filter with the internal 32k output resistance to make a lowpass filter. You want to get rid of not only the noise but any signal made from vibrations which are undesirable to capture.

What is the purpose of the input on RA0?

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4th May 2006, 05:16 AM	#1
yantheman	Pic18f452 Im using PIC18F452, ADXL203 and the given microchip target board. Im trying to read the 2 analog output of the accelerometer and do a ADC and display the digital value on an LCD. The connection is as shown in the attachment. Just checking is the connection correct? Anything missing ? Is my analog input correct as someone pointed to me that RE port cannot be used. Attached Thumbnails

4th May 2006, 05:17 PM	#2
Oznog	Yeah, I believe all the analog inputs are on PortA. Check your spec sheet. The output impedance of the ADXL devices is 32k ohms, at least the ones I know. That is FAR too high to provide to a PIC which needs 2.5k ohms max to live up to its full specifications. Also the ADXL devices need to be band-limited. Simply put a cap on the output, the cap will make an RC filter with the internal 32k output resistance to make a lowpass filter. You want to get rid of not only the noise but any signal made from vibrations which are undesirable to capture. What is the purpose of the input on RA0? __________________ I thought what I'd do was I'd pretend I was one of those deaf-mutes.