Rev. 1.00
48
March 24, 2020
Rev. 1.00
49
March 24, 2020
BS83A04C
4-Key Enhanced Touch I/O Flash MCU
BS83A04C
4-Key Enhanced Touch I/O Flash MCU
• PAC Register
Bit
7
6
5
4
3
2
1
0
Name
PAC7
PAC6
PAC5
PAC4
PAC3
PAC2
PAC1
PAC0
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
POR
1
1
1
1
1
1
1
1
Bit 7~0
PAC7~PAC0
: PA7~PA0 Pin type selection
0: Output
1: Input
Pin-shared Functions
The flexibility of the microcontroller range is greatly enhanced by the use of pins that have more
than one function. Limited numbers of pins can force serious design constraints on designers but by
supplying pins with multi-functions, many of these difficulties can be overcome. For these pins, the
desired function of the multi-function I/O pins is selected by a series of registers via the application
program control.
Pin-shared Function Selection Registers
The limited number of supplied pins in a package can impose restrictions on the amount of functions
a certain device can contain. However, by allowing the same pins to share several different functions
and providing a means of function selection, a wide range of different functions can be incorporated
into even relatively small package sizes. The device includes Port A Output Function Selection
register “n”, labeled as PASn, and Input Function Selection register, labeled as IFS, which can select
the desired functions of the multi-function pin-shared pins.
The most important point to note is to make sure that the desired pin-shared function is properly
selected and also deselected. For most pin-shared functions, to select the desired pin-shared function,
the pin-shared function should first be correctly selected using the corresponding pin-shared control
register. After that the corresponding peripheral functional setting should be configured and then
the peripheral function can be enabled. However, a special point must be noted for some digital
input pins, such as INT, CTCK etc, which share the same pin-shared control configuration with
their corresponding general purpose I/O functions when setting the relevant pin-shared control bit
fields. To select these pin functions, in addition to the necessary pin-shared control and peripheral
functional setup aforementioned, they must also be setup as an input by setting the corresponding bit
in the I/O port control register. To correctly deselect the pin-shared function, the peripheral function
should first be disabled and then the corresponding pin-shared function control register can be
modified to select other pin-shared functions.
Register
Name
Bit
7
6
5
4
3
2
1
0
PAS0
PAS07
PAS06
PAS05
PAS04
PAS03
PAS02
PAS01
PAS00
PAS1
PAS17
PAS16
—
—
PAS13
PAS12
PAS11
PAS10
IFS
—
—
—
—
—
—
IFS1
IFS0
Pin-shared Function Selection Register List
