AT90PWM216-16SE ATMEL [ATMEL Corporation], AT90PWM216-16SE Datasheet - Page 262

• Manufacturer Part Number: AT90PWM216-16SE
• Description: 8-bit Microcontroller with 16K Bytes In-System Programmable flash
• Manufacturer: ATMEL [ATMEL Corporation]

22.3.1
22.4
22.4.1
262
DAC Register Description
AT90PWM216/316
DAC Voltage Reference
Digital to Analog Conversion Control Register – DACON
Note that an interrupt flag will be set even if the specific interrupt is disabled or the Global Inter-
rupt Enable bit in SREG is cleared. A conversion can thus be triggered without causing an
interrupt. However, the interrupt flag must be cleared in order to trigger a new conversion at the
next interrupt event.
The reference voltage for the ADC (V
be selected as either AV
AV
ated from the internal bandgap reference (V
external AREF pin is directly connected to the DAC, and the reference voltage can be made
more immune to noise by connecting a capacitor between the AREF pin and ground. V
also be measured at the AREF pin with a high impedant voltmeter. Note that V
impedant source, and only a capacitive load should be connected in a system.
If the user has a fixed voltage source connected to the AREF pin, the user may not use the other
reference voltage options in the application, as they will be shorted to the external voltage. If no
external voltage is applied to the AREF pin, the user may switch between AV
reference selection. The first DAC conversion result after switching reference voltage source
may be inaccurate, and the user is advised to discard this result.
The DAC is controlled via three dedicated registers:
• Bit 7 – DAATE: DAC Auto Trigger Enable bit
Set this bit to update the DAC input value on the positive edge of the trigger signal selected with
the DACTS2-0 bit in DACON register.
Clear it to automatically update the DAC input when a value is written on DACH register.
• Bit 6:4 – DATS2, DATS1, DATS0: DAC Trigger Selection bits
These bits are only necessary in case the DAC works in auto trigger mode. It means if DAATE
bit is set.
Bit
Read/Write
Initial Value
• The DACON register which is used for DAC configuration
• DACH and DACL which are used to set the value to be converted.
CC
is connected to the DAC through a passive switch. The internal 2.56V reference is gener-
DAATE
R/W
7
0
CC
DATS2
R/W
6
0
, internal 2.56V reference, or external AREF pin.
DATS1
R/W
5
0
REF
) indicates the conversion range for the DAC. V
DATS0
R/W
BG
4
0
) through an internal amplifier. In either case, the
3
0
-
-
DALA
R/W
2
0
DAOE
R/W
1
0
DAEN
CC
R/W
0
0
7710D–AVR–08/09
and 2.56V as
REF
DACON
is a high
REF
REF
can
can