22.3.5 Input Selection
The ADC samples and converts the analog voltage differential at its positive and negative voltage inputs. The input multiplexers of the
ADC can connect these inputs to one of several internal nodes (e.g., temperature sensor) or to external signals via analog ports
(APORT0, APORT1, APORT2, APORT3 or APORT4).
The analog ports APORT1, APORT2, APORT3, and APORT4 connect to external pins via analog buses (BUSAX, BUSAY, BUSBX,
etc.) which are shared among other analog peripherals on the device. APORT1 through APORT4 are each 32 channels wide with con-
nections to two sub-buses: a 16-channel X bus and a 16-channel Y bus. In the ADC module, all X buses connect to the INP_MUX and
all Y buses connect to the INN_MUX as shown in
Figure 22.5 APORT connection to the ADC on page 724
. Connections to the X and
Y sub-buses alternate channels on the APORT. On APORT1 and APORT3, even-numbered channels connect to the X bus, and odd-
numbered channels connect to the Y bus. On APORT2 and APORT4, even-numbered channels connect to the X bus and odd-num-
bered channels connect to the Y bus.
Unlike APORT1 through APORT4, APORT0 is not a shared resource. It consists of a 16-channel X bus and a 16-channel Y bus, each
with dedicated I/O pin connections. Note that APORT0 is not available on all device families.
ch0 ch2 ch4 ch6
ch24 ch26 ch28 ch30
ch1 ch3 ch5 ch7
ch25 ch27 ch29 ch31
ch0 ch2 ch4 ch6
ch24 ch26 ch28 ch30
ch1 ch3 ch5 ch7
ch25 ch27 ch29 ch31
ch0 ch2 ch4 ch6
ch24 ch26 ch28 ch30
ch1 ch3 ch5 ch7
ch25 ch27 ch29 ch31
ch0 ch2 ch4 ch6
ch24 ch26 ch28 ch30
ch1 ch3 ch5 ch7
ch25 ch27 ch29 ch31
APORT1X
APORT2X
APORT3X
APORT4X
APORT1Y
APORT2Y
APORT3Y
APORT4Y
+
-
BUSAX
BUSBX
BUSCX
BUSDX
BUSAY
BUSBY
BUSCY
BUSDY
BUSADC0X
ch0 ch1
ch2 ch3
ch15
ch14
ch13
ch12
BUSADC0Y
ch0 ch1
ch2 ch3
ch15
ch14
ch13
ch12
APORT0X
APORT0Y
INP_MUX
INN_MUX
Figure 22.5. APORT connection to the ADC
For differential measurements, one input must be chosen from an X bus and the other from a Y bus. Choosing both inputs from an X
bus or both from a Y bus will generate a PROGERR interrupt (if enabled) of NEGSELCONF type. The PROGERR type can be checked
in the ADCn_STATUS register.
EFM32JG1 Reference Manual
ADC - Analog to Digital Converter
silabs.com
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