UPSD3254 STMICROELECTRONICS [STMicroelectronics], UPSD3254 Datasheet - Page 47

• Manufacturer Part Number: UPSD3254
• Description: Flash Programmable System Devices with 8032 Microcontroller Core
• Manufacturer: STMICROELECTRONICS [STMicroelectronics]

I/O PORTS (MCU MODULE)
The MCU Module has five ports: Port 0, Port 1,
Port 2, Port 3, and Port 4. (Refer to the PSD Mod-
ule section on I/O ports A,B,C and D). Ports P0
and P2 are dedicated for the external address and
data bus and is not available in the 52-pin package
devices.
Port 1 - Port 3 are the same as in the standard
8032 micro-controllers, with the exception of the
additional special peripheral functions. All ports
are bi-directional. Pins of which the alternative
function is not used may be used as normal bi-di-
rectional I/O.
The use of Port 1 -Port 4 pins as alternative func-
tions are carried out automatically by the
uPSD325X devices provided the associated SFR
Bit is set HIGH.
The following SFR registers (Tables 29, 30, and
31) are used to control the mapping of alternate
functions onto the I/O port bits. Port 1 alternate
Table 28. I/O Port Functions
Table 29. P1SFS (91H)
Table 30. P3SFS (93H)
Table 31. P4SFS (94H)
from I
0 = Port 3.7
0=Port 1.7
0=Port 4.7
1=PWM 4
1=ACH3
1 = SCL
7
7
2
7
C unit
Port Name
USB +/-
from I
0 = Port 3.6
Port 1
Port 3
Port 4
0=Port 1.6
0=Port 4.6
1=PWM 3
1=ACH2
1 = SDA
6
6
2
6
C unit
0=Port 1.5
0=Port 4.5
1=PWM 2
1=ACH1
5
5
5
UPSD3254A, UPSD3254BV, UPSD3253B, UPSD3253BV
0=Port 1.4
0=Port 4.4
1=PWM 1
1=ACH0
4
4
4
Main Function
USB +/- Only
GPIO
GPIO
GPIO
0=Port 4.3
1=PWM 0
functions are controlled using the P1SFS register,
except for Timer 2 and the 2nd UART which are
enabled by their configuration registers. P1.0 to
P1.3 are default to GPIO after reset.
Port 3 pins 6 and 7 have been modified from the
standard 8032. These pins that were used for
READ and WRITE control signals are now GPIO
or I
assigned to dedicated pins.
Port 3 (I
trolled using the P3SFS and P4SFS Special Func-
tion Selection registers. After a reset, the I/O pins
default to GPIO. The alternate function is enabled
if the corresponding bit in the PXSFS register is
set to '1.' Other Port 3 alternative functions (UART,
Interrupt, and Timer/Counter) are enabled by their
configuration register and do not require setting of
the bits in P3SFS.
Bits are reserved.
2
3
3
3
C bus pins. The READ and WRITE pins are
Bits Reserved
2
C) and Port 4 alternate functions are con-
0=Port 4.2
1=V
2
2
2
SYNC
2nd UART - Bits 2,3
Interrupt - Bits 2,3
Timer 2 - Bits 0,1
Timers - Bits 4,5
UART - Bits 0,1
PWM - Bits 3..7
0=Port 4.1
ADC - Bits 4..7
DDC - Bits 0..2
1=DDC -
I
2
Alternate
C - Bits 6,7
SCL
1
1
1
Bits Reserved
0=Port 4.0
1=DDC -
SDA
0
0
0
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