KS57C2308/P2308/C2316/P2316

I/O PORTS

 

 

PORT MODE FLAGS (PM FLAGS)

Port mode flags (PM) are used to configure I/O ports to input or output mode by setting or clearing the corresponding I/O buffer.

For convenient program reference, PM flags are organized into two groups — PMG1 and PMG2 as shown in Table 10-3. They are addressable by 8-bit write instructions only.

When a PM flag is "0", the port is set to input mode; when it is "1", the port is enabled for output. RESET clears all port mode flags to logical zero, automatically configuring the corresponding I/O ports to input mode.

Table 10-3. Port Mode Group Flags

PM Group ID

Address

Bit 3/7

Bit 2/6

Bit 1/5

Bit 0/4

 

 

 

 

 

 

PMG1

FE8H

PM3.3

PM3.2

PM3.1

PM3.0

 

 

 

 

 

 

 

FE9H

PM6.3

PM6.2

PM6.1

PM6.0

 

 

 

 

 

 

PMG2

FECH

“0”

PM2

“0”

“0”

 

 

 

 

 

 

 

FEDH

PM7

“0”

PM5

PM4

 

 

 

 

 

 

+PROGRAMMING TIP — Configuring I/O Ports to Input or Output

Configure ports 3 and 6 as an output port:

BITS

EMB

 

SMB

15

 

LD

EA,#0FFH

 

LD

PMG1,EA

; P3 and P6 Output

PULL-UP RESISTOR MODE REGISTER (PUMOD)

The pull-up resistor mode registers (PUMOD1 and PUMOD2) are used to assign internal pull-up resistors by software to specific ports. When a configurable I/O port pin is used as an output pin, its assigned pull-up resistor is automatically disabled, even though the pin's pull-up is enabled by a corresponding PUMOD bit setting.

PUMOD1 is addressable by 8-bit write instructions only, and PUMOD2 by 4-bit write instruction only. RESET clears PUMOD register values to logic zero, automatically disconnecting all software-assignable port pull-up resistors.

Table 10-4. Pull-Up Resistor Mode Register (PUMOD) Organization

PUMOD ID

Address

Bit 3/7

Bit 2/6

Bit 1/5

Bit 0/4

 

 

 

 

 

 

PUMOD

FDCH

PUR3

PUR2

PUR1

PUR0

 

 

 

 

 

 

 

FDDH

PUR7

PUR6

PUR5

PUR4

 

 

 

 

 

 

NOTE: When bit = "1", a pull-up resistor is assigned to the corresponding I/O port: PUR3 for port 3, PUR2 for port 2, and so on.

10-3

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Samsung KS57C2308 manual Port Mode Flags PM Flags, PULL-UP Resistor Mode Register Pumod, Pumod ID