NS32FV100 Datasheet, PDF (43/96 Pages) Texas Instruments – NS32FX100 NS32FV100 NS32FX200 System Controller

2 0 Architecture (Continued)
with other modules and are allocated by software Input
pins can always be read even if shared with another mod-
ule Output pins can be enabled or disabled (TRI-STATE)
The characteristics of the four bits which may be associated
with the ports are as follows
DI Data In bit Read only Holds current value state of
the pin
DO Data Out bit Write read Holds the value to be
driven onto the pin when the respective MS bit is
‘‘0’’ When read back DO is not effected by the
MS bit
EN Enable bit Write read TRI-STATE when EN e 0
drive when EN e 1
MS Module Select bit Write read Selects output pin
source and input pin destination
When MS e 0 pin is connected to the port
When MS e 1 pin is connected to the module
that shares this pin
When an input signal is assigned to a module (by setting the
respective MS bit to ‘‘1’’) the associated EN bit must be
cleared to ‘‘0’’
FIGURE 2-23 Port A
te Two bits are associated with each input pin of this port
DI Data In Bit
MS Module Select Bit
le _{FIGURE2-24 PortB}
o Three bits are associated with each output pin of this port
DO Data Out Bit
EN Enable Bit
Obs ^{MS Module Select Bit}
TL EE 11331 – 28
TL EE 11331 – 29
FIGURE 2-25 Port C
42
TL EE 11331 – 30