Datasheet

 2003-2013 Microchip Technology Inc. DS30498D-page 159
PIC16F7X7
12.6 A/D Conversions
Figure 12-3 shows the operation of the A/D converter
after the GO/DONE
bit has been set and the
ACQT2:ACQT0 bits are cleared. A conversion is
started after the following instruction to allow entry into
Sleep mode before the conversion begins.
Figure 12-4 shows the operation of the A/D converter
after the GO/DONE
bit has been set, the
ACQT2:ACQT0 bits are set to ‘010’ and a 4 T
AD
acquisition time is selected before the conversion
starts.
Clearing the GO/DONE
bit during a conversion will
abort the current conversion. The A/D Result register
pair will NOT be updated with the partially completed
A/D conversion sample. This means the
ADRESH:ADRESL registers will continue to contain
the value of the last completed conversion (or the last
value written to the ADRESH:ADRESL registers).
After the A/D conversion is completed or aborted, a
2T
AD wait is required before the next acquisition can be
started. After this wait, acquisition on the selected
channel is automatically started.
FIGURE 12-3: A/D CONVERSION TAD CYCLES (ACQT<2:0> = 000, TACQ = 0)
FIGURE 12-4: A/D CONVERSION T
AD CYCLES (ACQT<2:0> = 010, TACQ = 4 TAD)
Note: The GO/DONE bit should NOT be set in
the same instruction that turns on the A/D.
TAD1
TAD2
TAD3
TAD4 TAD5
TAD6 TAD7
TAD8 TAD11
Set GO/DONE bit
Holding capacitor is disconnected from analog input (typically 100 ns)
TAD9 TAD10
TCY - TAD
Next Q4: ADRESH/ADRESL is loaded, GO/DONE bit is cleared,
ADIF bit is set, holding capacitor is connected to analog input.
Conversion starts
b0
b9
b6
b5
b4
b3
b2
b1
b8
b7
1
2
3
4 5
6 7
8 11
Set GO/DONE bit
(Holding capacitor is disconnected)
9 10
Next Q4: ADRESH:ADRESL is loaded, GO/DONE bit is cleared,
ADIF bit is set, holding capacitor is reconnected to analog input.
Conversion starts
1
2
3
4
(Holding capacitor continues
acquiring input)
T
ACQT Cycles
TAD Cycles
Automatic
Acquisition
Time
b0b9
b6
b5 b4
b3
b2
b1
b8
b7