
238
8023F–AVR–07/09
ATmega325P/3250P
Table 23-4.
Boundary-scan Signals for the ADC
Signal
Name
Direction as
seen
from the ADC
Description
Recommende
d Input when
not in use
Output Values when
recommended inputs are
used, and CPU is not using the
ADC
COMP
Output
Comparator Output
0
ACLK
Input
Clock signal to differential amplifier
implemented as Switch-cap filters
00
ACTEN
Input
Enable path from differential amplifier to
the comparator
00
ADCBGEN
Input
Enable Band-gap reference as negative
input to comparator
00
ADCEN
Input
Power-on signal to the ADC
0
AMPEN
Input
Power-on signal to the differential amplifier
0
DAC_9
Input
Bit 9 of digital value to DAC
1
DAC_8
Input
Bit 8 of digital value to DAC
0
DAC_7
Input
Bit 7 of digital value to DAC
0
DAC_6
Input
Bit 6 of digital value to DAC
0
DAC_5
Input
Bit 5 of digital value to DAC
0
DAC_4
Input
Bit 4 of digital value to DAC
0
DAC_3
Input
Bit 3 of digital value to DAC
0
DAC_2
Input
Bit 2 of digital value to DAC
0
DAC_1
Input
Bit 1 of digital value to DAC
0
DAC_0
Input
Bit 0 of digital value to DAC
0
EXTCH
Input
Connect ADC channels 0 - 3 to by-pass
path around differential amplifier
11
GNDEN
Input
Ground the negative input to comparator
when true
00
HOLD
Input
Sample & Hold signal. Sample analog
signal when low. Hold signal when high. If
differential amplifier are used, this signal
must go active when ACLK is high.
11
IREFEN
Input
Enables Band-gap reference as AREF
signal to DAC
00
MUXEN_7
Input
Input Mux bit 7
0
MUXEN_6
Input
Input Mux bit 6
0
MUXEN_5
Input
Input Mux bit 5
0
MUXEN_4
Input
Input Mux bit 4
0
MUXEN_3
Input
Input Mux bit 3
0
MUXEN_2
Input
Input Mux bit 2
0
MUXEN_1
Input
Input Mux bit 1
0
MUXEN_0
Input
Input Mux bit 0
1