LM3S1621 Datasheet, PDF (436/947 Pages) Texas Instruments – ARM and Thumb are registered trademarks and Cortex is a trademark

General-Purpose Input/Outputs (GPIOs)
Register 21: GPIO Analog Mode Select (GPIOAMSEL), offset 0x528
Important: This register is only valid for ports D and E; the corresponding base addresses for the
remaining ports are not valid.
If any pin is to be used as an ADC input, the appropriate bit in GPIOAMSEL must be
set to disable the analog isolation circuit.
The GPIOAMSEL register controls isolation circuits to the analog side of a unified I/O pad. Because
the GPIOs may be driven by a 5-V source and affect analog operation, analog circuitry requires
isolation from the pins when they are not used in their analog function.
Each bit of this register controls the isolation circuitry for the corresponding GPIO signal. For
information on which GPIO pins can be used for ADC functions, refer to Table 19-5 on page 851.
GPIO Analog Mode Select (GPIOAMSEL)
GPIO Port A (APB) base: 0x4000.4000
GPIO Port A (AHB) base: 0x4005.8000
GPIO Port B (APB) base: 0x4000.5000
GPIO Port B (AHB) base: 0x4005.9000
GPIO Port C (APB) base: 0x4000.6000
GPIO Port C (AHB) base: 0x4005.A000
GPIO Port D (APB) base: 0x4000.7000
GPIO Port D (AHB) base: 0x4005.B000
GPIO Port E (APB) base: 0x4002.4000
GPIO Port E (AHB) base: 0x4005.C000
GPIO Port F (APB) base: 0x4002.5000
GPIO Port F (AHB) base: 0x4005.D000
GPIO Port G (APB) base: 0x4002.6000
GPIO Port G (AHB) base: 0x4005.E000
GPIO Port H (APB) base: 0x4002.7000
GPIO Port H (AHB) base: 0x4005.F000
GPIO Port J (APB) base: 0x4003.D000
GPIO Port J (AHB) base: 0x4006.0000
Offset 0x528
Type R/W, reset 0x0000.0000
31
30
29
28
27
26
25
24
23
22
21
20
19
18
17
16
reserved
Type RO
RO
RO
RO
RO
RO
RO
RO
RO
RO
RO
RO
RO
RO
RO
RO
Reset
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
15
14
13
12
11
10
9
8
7
6
5
4
3
2
1
0
reserved
GPIOAMSEL
Type RO
RO
RO
RO
RO
RO
RO
RO
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
Reset
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
Bit/Field
31:8
Name
reserved
Type
RO
Reset Description
0x0000.00 Software should not rely on the value of a reserved bit. To provide
compatibility with future products, the value of a reserved bit should be
preserved across a read-modify-write operation.
436
January 21, 2012
Texas Instruments-Production Data