dsPIC30F Family Reference Manual
DS70064C-page 17-28 © 2004 Microchip Technology Inc.
17.12.3.7 Sample Time Considerations for Automatic Sampling/Conversion Sequences
Different sample/conversion sequences provide different available sampling times for the S/H
channel to acquire the analog signal. The user must ensure the sampling time exceeds the
sampling requirements, as outlined in Section 17.16 “A/D Sampling Requirements”.
Assuming that the module is set for automatic sampling and an external trigger pulse is used as
the conversion trigger, the sampling interval is a portion of the trigger pulse interval.
If the SIMSAM bit specifies simultaneous sampling, the sampling time is the trigger pulse period
less the time required to complete the specified conversions.
Equation 17-5: Available Sampling Time, Simultaneous Sampling
If the SIMSAM bit specifies sequential sampling, the sampling time is the trigger pulse period less
the time required to complete only one conversion.
Equation 17-6: Available Sampling Time, Sequential Sampling
T
SMP = Trigger Pulse Interval (TSEQ) –
Channels per Sample (CH/S) * Conversion Time (T
CONV)
T
SMP =TSEQ – (CH/S * TCONV)
Note 1: CH/S specified by CHPS<1:0> bits.
2: T
SEQ is the trigger pulse interval time.
T
SMP = Trigger Pulse Interval (TSEQ) –
Conversion Time (T
CONV)
T
SMP =TSEQ – TCONV
Note: T
SEQ is the trigger pulse interval time.
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