PIC16F872 Datasheet, PDF (91/160 Pages) Microchip Technology – 28-Pin, 8-Bit CMOS FLASH Microcontroller

PIC16F872
10.4 A/D Conversions
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. That is, 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 aborted, a 2TAD wait is
required before the next acquisition is started. After
this 2TAD wait, acquisition on the selected channel is
automatically started.
In Figure 10-3, after the GO bit is set, the first time seg-
ment has a minimum of TCY and a maximum of TAD.
Note: The GO/DONE bit should NOT be set in
the same instruction that turns on the A/D.
FIGURE 10-3: A/D CONVERSION TAD CYCLES
TCY to TAD TAD1 TAD2 TAD3 TAD4 TAD5 TAD6 TAD7 TAD8 TAD9 TAD10 TAD11
b9 b8 b7 b6 b5 b4 b3 b2 b1 b0
Conversion Starts
Holding capacitor is disconnected from analog input (typically 100 ns)
Set GO bit
ADRES is loaded,
GO bit is cleared,
ADIF bit is set,
holding capacitor is connected to analog input.
© 1999 Microchip Technology Inc.
Preliminary
DS30221A-page 91