Microchip Technology dsPIC30F - Page 411

© 2004 Microchip Technology Inc. DS70064C-page 17-35
Section 17. 10-bit A/D Converter
10-bit A/D
Converter
17
17.15.3 Example: Sampling Three Inputs Frequently While Scanning Four Other Inputs
Figure 17-16 and Table 17-4 shows how the A/D converter could be configured to sample three
inputs frequently using sample/hold channels CH1, CH2 and CH3; while four other inputs are
sampled less frequently by scanning them using sample/hold channel CH0. In this case, only
MUX A inputs are used, and all 4 channels are sampled simultaneously. Four different inputs
(AN4, AN5, AN6, AN7) are scanned in CH0, whereas AN0, AN1 and AN2 are the fixed inputs for
CH1, CH2 and CH3, respectively. Thus, in every set of 16 samples, AN0, AN1 and AN2 would
be sampled 4 times, while AN4, AN5, AN6 and AN7 would be sampled only once each.
Figure 17-16: Converting Three Inputs, Four Times and Four Inputs, One Time/Interrupt
ADCLK
SAMP
DONE
Input to CH0
AN4
TSAMP
ADIF
TCONVTCONVTCONVTCONV
AN0
AN1
AN2
Input to CH1
Input to CH2
Input to CH3
ADCBUFD
ADCBUFE
ADCBUFF
AN5
TSAMP
AN0
AN1
AN2
AN7
TSAMP
AN0
AN1
AN2
ASAM
AN4
AN0
AN1
AN2
ADCBUF0
ADCBUF1
ADCBUF2
ADCBUF3
ADCBUFC
AN6
AN0
AN1
AN2
Conversion
Trigger
T
CONVTCONVTCONVTCONV TCONVTCONVTCON VTCONV