Using i/o pins io3, io2, io1, and io0 – Texas Instruments TMS320C2XX User Manual

Page 413

Controlling and Resetting the Port

10-15

Asynchronous Serial Port

10.3.5 Using I/O Pins IO3, IO2, IO1, and IO0

Pins IO3, IO2, IO1, and IO0 can be individually configured as inputs or outputs
and can be used as handshake control for the asynchronous serial port or as
general-purpose I/O pins. They are software-controlled through the asynchro-
nous serial port control register (ASPCR) and the I/O status register (IOSR),
as shown in Figure 10–5.

Figure 10–5. Example of the Logic for Pins IO0–IO3

Level change

detect

CIO0bit = 1

CIO0bit = 0

General - purpose

I / O pin

IO0

DIO3

DIO2

DIO1

DIO0

IO3

IO2

IO1

IO0

Delta interrupt

I/O status register (IOSR)

DIM bit

The four LSBs of the ASPCR, bits CIO0–CIO3, are for configuring each pin as
an input or an output. For example, as shown in the figure, setting CIO0 to 1
configures IO0 as an output; setting CIO0 to 0 configures IO0 as an input. At
reset, CIO0–CIO3 are all cleared to 0, making all four of the the pins inputs.
Table 10–3 summarizes the configuration of the pins.

Table 10–3. Configuring Pins IO0–IO3 with ASPCR Bits CIO0–CIO3

БББ

CIO0

Bit

ББББ

IO0
Pin

ББББ

CIO1

Bit

ББББ

IO1
Pin

БББ

CIO2

Bit

ББББ

IO2
Pin

ББББ

CIO3

Bit

ББББ

IO3
Pin

Input

БББ

ББББ

Output

ББББ

Output

БББ

ББББ

Output

ББББ

Output