Datasheet

PIC16(L)F1454/5/9
DS41639A-page 158 Preliminary  2012 Microchip Technology Inc.
16.2 ADC Operation
16.2.1 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.
16.2.2 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 ADRESH and ADRESL registers with
new conversion result
16.2.3 TERMINATING A CONVERSION
If a conversion must be terminated before completion,
the GO/DONE
bit can be cleared in software. The
ADRESH and ADRESL registers will be updated with
the partially complete Analog-to-Digital conversion
sample. Incomplete bits will match the last bit
converted.
16.2.4 ADC OPERATION DURING SLEEP
The ADC module can operate during Sleep. This
requires the ADC clock source to be set to the F
RC
option. When the FRC clock source is selected, the
ADC waits one additional instruction before starting the
conversion. This allows the SLEEP instruction to be
executed, which can reduce system noise during the
conversion. If the ADC interrupt is enabled, the device
will wake-up from Sleep when the conversion
completes. If the ADC interrupt is disabled, the ADC
module is turned off after the conversion completes,
although the ADON bit remains set.
When the ADC clock source is something other than
F
RC, a SLEEP instruction causes the present conver-
sion to be aborted and the ADC module is turned off,
although the ADON bit remains set.
16.2.5 AUTO-CONVERSION TRIGGER
The auto-conversion trigger allows periodic ADC mea-
surements without software intervention. When a rising
edge of the selected source occurs, the GO/DONE
bit
is set by hardware.
The auto-conversion trigger source is selected with the
TRIGSEL<2:0> bits of the ADCON2 register.
Using the auto-conversion trigger does not assure
proper ADC timing. It is the user’s responsibility to
ensure that the ADC timing requirements are met.
Auto-Conversion sources are:
•TMR0
•TMR1
•TMR2
•C1
•C2
Note: The GO/DONE bit should not be set in the
same instruction that turns on the ADC.
Refer to
Section 16.2.6 “A/D Conver-
sion 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.