T5L_ASIC Development Guide
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3.6 IO
T5L OS 8051 has three 8 bit parallel ports(P0-P2) and a 4 bit parallel port(P3.0-P3.3), a total of 28
IO ports. P0-P0.7 of P0 port is multiplexed with UART and CAN interface, and multiplexing function
or IO function can be selected through MUX_SEL register.
The input of all IO ports is always open, the input is floating, and there is no internal pull-up or pull-
down. When IO port is used as output, it is necessary to open the output control, and the output
driving ability can also be configured.
Because the IO interface of power-on reset process is input mode, when used as output, it must be
pulled up or pulled down externally to ensure that the reliable output of power-on process is
ensured, and will not malfunction due to IO floating.
P3.0 is external interrupt 0, and P3.1 is external interrupt 1 input. It can be configured as low level
trigger (0) or jump down edge trigger (1) through IT0 and IT1.
In addition to the need to control the output switch, output strength and peripheral multiplexing
power-on initialization configuration, the subsequent use of IO is consistent with the standard 8051.
IO-related SFR are shown in the following table:
SFR name
Address
Instructions
P0
0x80
Addressable by bit, same as standard 8051
P1
0x90
Addressable by bit, same as standard 8051
P2
0xA0
Addressable by bit, same as standard 8051
P3
0xB0
It can be addressable by bit, the same as standard 8051, only P3.0-P3.3 is valid.
POMDOUT
0xB7
P0 Interface Output Configuration:
.7 0=P0.7Output shutdown
1=P0.7Output Open (push-pull output);
.6 0=P0.6Output shutdown
1=P0.6Output Open (push-pull output );
.5 0=P0.5Output shutdown
1=P0.5Output Open (push-pull output );
.4 0=P0.4Output shutdown
1=P0.4Output Open (push-pull output);
.3 0=P0.3Output shutdown
1=P0.3Output Open (push-pull output);
.2 0=P0.2Output shutdown
1=P0.2Output Open (push-pull output);
.1 0=P0.1Output shutdown
1=P0.1Output Open (push-pull output);
.0 0=P0.0Output shutdown
1=P0.0Output Open (push-pull output);
P1MDOUT
0xBC
P1 interface output configuration
P2MDOUT
0xBD
P2 interface output configuration
P3MDOUT
0xBE
P3 interface output configuration
