I/O

The following table shows the bit locations of the I/O port mapping:

 

 

 

(8-bit wide location)

 

 

 

 

 

 

 

07

06

05

04

03

02

01

00

 

 

 

 

 

 

 

 

 

 

 

A port data register . . . . . address 0x00

 

A7

A6

A5

A4

A3

A2

A1

A0

 

 

 

 

 

 

 

 

 

 

A port control register . . . address 0x04

 

C

C

C

C

C

C

C

C

 

 

 

 

 

 

 

 

 

 

 

B port data register . . . . . address 0x08

 

B7

B6

B5

B4

B3

B2

B1

B0

 

 

 

 

 

 

 

 

 

 

B port control register . . . address 0x0C

 

C

C

C

C

C

C

C

C

 

 

 

 

 

 

 

 

 

 

 

C port data register . . . . . address 0x10

 

C7

C6

C5

C4

C3

C2

C1

C0

 

 

 

 

 

 

 

 

 

 

C port control register . . . address 0x14

 

C

C

C

C

C

C

C

C

 

 

 

 

 

 

 

 

 

 

 

D port data register . . . . . address 0x18

 

D7

D6

D5

D4

D3

D2

D1

D0

 

 

 

 

 

 

 

 

 

 

D port control register. . address 0x1C

 

C

C

C

C

C

C

C

C

 

 

 

 

 

 

 

 

 

 

 

E port data register . . . . . address 0x20

 

E7

E6

E5

E4

E3

E2

E1

E0

 

 

 

 

 

 

 

 

 

 

E port control register . . . address 0x24

 

C

C

C

C

C

C

C

C

 

 

 

 

 

 

 

 

 

 

 

 

A7, B7, C7, D7, E7

: data register

 

 

 

 

 

 

 

 

 

C

: control register (0 = IN, 1 = OUT)

 

 

 

 

 

0x00 : state of control register after RESET low

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Ports D4 and D5 may be dedicated to the Comparator function, if the Comparator Enable bit is set. If so, then bits 4 and 5 of the D port Control register must be CLEAR. Please refer to Section 3.3, Comparator, for details.

Port D0 is connected to the branch condition COND1. Port D1 is connected to the branch condition COND2, assuming the comparator is disabled. Please refer to Section 3.1.4, Branch on D Port, (and to Section 3.3, Comparator) for more information. External interrupts can be detected when transitions occur on ports D2, D3, D4, and D5. The interrupts associated with the D port are supported whether those pins are programmed as inputs or as outputs.

3.1.2Dedicated Input Port F

Port F is an 8-bit wide input-only port. The data presented to the input pin can be read by referring to the appropriate bit in the F port data register, address 0x28. This is done using the IN instruction, with the 0x28 address as an argument. The state of the F port data registers is not initialized with RESET. After RESET is taken high, the state of the F port data register is unknown.

Each of the pins at port F has a programmable pull-up resistor. All eight pullup resistors can be enabled by setting the enable pullup (EP) in the interrupt/gen- eral control register (IntGenCtrl). The address of the IntGenCtrl is 0x38, and the location of the EP bit is 12. Clearing the EP bit disables the eight pullups,

3-4

Page 68
Image 68
Texas Instruments MSP50C6xx manual Dedicated Input Port F