UM10429
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© NXP B.V. 2010. All rights reserved.
User manual
Rev. 1 — 20 October 2010
52 of 258
NXP Semiconductors
UM10429
Chapter 7: LPC1102 I/O Configuration
7.3.3 Hysteresis
The input buffer for digital functions can be configured with hysteresis or as plain buffer
through the IOCON registers (see the
LPC1102 data sheet
for details).
If the external pad supply voltage V
DD
is between 2.5 V and 3.6 V, the hysteresis buffer
can be enabled or disabled. If V
DD
is below 2.5 V, the hysteresis buffer must be
disabled
to use the pin in input mode.
7.3.4 A/D-mode
In A/D-mode, the digital receiver is disconnected to obtain an accurate input voltage for
analog-to-digital conversions. This mode can be selected in those IOCON registers that
control pins with an analog function. If A/D mode is selected, Hysteresis and Pin mode
settings have no effect.
For pins without analog functions, the A/D-mode setting has no effect.
7.4 Register description
The I/O configuration registers control the PIO port pins, the inputs and outputs of all
peripherals and functional blocks and the ADC input pins.
Each port pin PIOn_m has one IOCON register assigned to control the pin’s function and
electrical characteristics.
Table 45.
Register overview: I/O configuration (base address 0x4004 4000)
Name
Access
Address
offset
Description
Reset
value
Reference
-
-
0x000 -
0x008
Reserved
-
-
IOCON_RESET_PIO0_0
R/W
0x00C
I/O configuration for pin RESET/PIO0_0 0xD0
-
-
0x010 -
0x05C
Reserved
-
-
IOCON_PIO0_8
R/W
0x060
I/O configuration for pin
PIO0_8/MISO0/CT16B0_MAT0
0xD0
IOCON_PIO0_9
R/W
0x064
I/O configuration for pin
PIO0_9/MOSI0/CT16B0_MAT1
0xD0
IOCON_SWCLK_PIO0_10
R/W
0x068
Reserved
-
-
-
-
0x06C -
0x070
Reserved
-
-
IOCON_R_PIO0_11
R/W
0x074
I/O configuration for pin
R/PIO0_11/AD0/CT32B0_MAT3
0xD0
IOCON_R_PIO1_0
R/W
0x078
I/O configuration for pin
R/PIO1_0/AD1/CT32B1_CAP0
0xD0
IOCON_R_PIO1_1
R/W
0x07C
I/O configuration for pin
R/PIO1_1/AD2/CT32B1_MAT0
0xD0
IOCON_R_PIO1_2
R/W
0x080
I/O configuration for pin
R/PIO1_2/AD3/CT32B1_MAT1
0xD0
-
-
0x084 -
0x08C
Reserved
-
-