Microchip Technology DM183037 Data Sheet
2012 Microchip Technology Inc.
DS30575A-page 465
PIC18F97J94 FAMILY
22.5.3.4
Sample Time Considerations For
Automatic Sampling/conversion
Sequences
Automatic Sampling/conversion
Sequences
Different sample/conversion sequences provide differ-
ent available sampling times for the S/H channel to
acquire the analog signal. The user must ensure the
ent available sampling times for the S/H channel to
acquire the analog signal. The user must ensure the
sampling time satisfies the sampling requirements, as
outlined in
outlined in
.
Assuming that the module is set for automatic sam-
pling, and an external trigger pulse is used as the con-
version trigger, the sampling interval is a portion of the
trigger pulse interval. The sampling time is the trigger
pulse period, less the time required to complete the
conversion.
pling, and an external trigger pulse is used as the con-
version trigger, the sampling interval is a portion of the
trigger pulse interval. The sampling time is the trigger
pulse period, less the time required to complete the
conversion.
EQUATION 22-3:
CALCULATING AVAILABLE SAMPLING TIME FOR SEQUENTIAL SAMPLING
FIGURE 22-8:
MANUAL SAMPLE START, CONVERSION TRIGGER-BASED CONVERSION
START
START
FIGURE 22-9:
AUTO-SAMPLE START, CONVERSION TRIGGER-BASED CONVERSION START
T
SMP
= Trigger Pulse Interval (T
SEQ
) – Conversion Time (T
CONV
) = T
SEQ
– T
CONV
Conversion Trigger
A/D CLK
SAMP
ADC1BUF0
T
SAMP
T
CONV
BSF AD1CON1, SAMP
Instruction Execution
Conversion Trigger
A/D CLK
SAMP
ADC1BUF0
T
SAMP
T
CONV
BSF AD1CON1, ASAM
T
CONV
T
SAMP
ADC1BUF1
DONE
Reset by
Software
Instruction Execution