274
7647H–AVR–03/12
Atmel ATmega16/32/64/M1/C1
21.4.2.2 DALA = 1
To work with the 10-bit DAC, two registers have to be updated. In order to avoid intermediate
value, the DAC input values which are really converted into analog signal are buffered into
unreachable registers. In normal mode, the update of the shadow register is done when the reg-
ister DACH is written.
In case DAATE bit is set, the DAC input values will be updated on the trigger event selected
through DATS bits.
In order to avoid wrong DAC input values, the update can only be done after having written
respectively DACL and DACH registers. It is possible to work on 8-bit configuration by only writ-
ing the DACH value. In this case, update is done each trigger event.
In case DAATE bit is cleared, the DAC is in an automatic update mode. Writing the DACH regis-
ter automatically update the DAC input values with the DACH and DACL register values.
It means that whatever is the configuration of the DAATE bit, changing the DACL register has no
effect on the DAC output until the DACH register has also been updated. So, to work with 10
bits, DACL must be written first before DACH. To work with 8-bit configuration, writing DACH
allows the update of the DAC.
Bit 76543210
DAC9 DAC8 DAC7 DAC6 DAC5 DAC4 DAC3 DAC2 DACH
DAC1DAC0------DACL
Read/Write R/W R/W R/W R/W R/W R/W R/W R/W
R/W R/W R/W R/W R/W R/W R/W R/W
Initial Value00000000
00000000
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