Datasheet

 2010-2013 Microchip Technology Inc. DS40001430E-page 77
PIC16(L)F720/721
FIGURE 9-2: ANALOG-TO-DIGITAL CONVERSION TAD CYCLES
9.1.4 INTERRUPTS
The ADC module allows for the ability to generate an
interrupt upon completion of an Analog-to-Digital
conversion. The ADC Interrupt Flag is the ADIF bit in
the PIR1 register. The ADC Interrupt Enable is the
ADIE bit in the PIE1 register. The ADIF bit must be
cleared in software.
This interrupt can be generated while the device is
operating or while in Sleep. If the device is in Sleep, the
interrupt will wake-up the device. Upon waking from
Sleep, the next instruction following the SLEEP
instruction is always executed. If the user is attempting
to wake-up from Sleep and resume in-line code
execution, the GIE and PEIE bits of the INTCON
register must be disabled. If the GIE and PEIE bits of
the INTCON register are enabled, execution will switch
to the Interrupt Service Routine.
Please refer to Section 9.1.4 “Interrupts” for more
information.
9.2 ADC Operation
9.2.1 STARTING A CONVERSION
To enable the ADC module, the ADON bit of the
ADCON0 register must be set to a ‘1’. Setting the GO/
DONE
bit of the ADCON0 register to a ‘1’ will start the
Analog-to-Digital conversion.
9.2.2 COMPLETION OF A CONVERSION
When the conversion is complete, the ADC module will:
• Clear the GO/DONE
bit
• Set the ADIF Interrupt Flag bit
• Update the ADRES register with new conversion
result
9.2.3 TERMINATING A CONVERSION
If a conversion must be terminated before completion,
the GO/DONE
bit can be cleared in software. The
ADRES register will be updated with the partially com-
plete Analog-to-Digital conversion sample. Incomplete
bits will match the last bit converted.
TAD1 TAD2 TAD3 TAD4 TAD5 TAD6 TAD7 TAD8 TAD9
Set GO/DONE bit
Holding Capacitor is disconnected from Analog Input (typically 100 ns)
b7 b6 b5 b4 b3 b2 b1 b0
TCY to TAD
Conversion Starts
ADRES register is loaded,
GO/DONE bit is cleared,
ADIF bit is set,
Holding capacitor is connected to analog input
TAD0
Note 1: The ADIF bit is set at the completion of
every conversion, regardless of whether
or not the ADC interrupt is enabled.
2: The ADC operates during Sleep only
when the F
RC oscillator is selected.
Note: The GO/DONE bit should not be set in the
same instruction that turns on the ADC.
Refer to Section 9.2.6 “A/D Conversion
Procedure”.
Note: A device Reset forces all registers to their
Reset state. Thus, the ADC module is
turned off and any pending conversion is
terminated.