SDA5523 Micronas Semiconductor, SDA5523 Datasheet - Page 25

• Manufacturer Part Number: SDA5523
• Description: SDA55xx TVText Pro
• Manufacturer: Micronas Semiconductor

DATA SHEET
Table 2–9: Ports and I/O-pins, continued
2.2.9.1. Read Modify Write Feature
‘Read-modify-write’ commands are instructions that
read a value, possibly change it, and then rewrite it to
the latch. The read-modify-write instructions are listed
in Table 2–10.
If the destination operand is a port or a port bit, these
instructions read the information stored in the latch
rather than the status of the pin. The read-modify-write
instructions are directed to the latch rather than to the
pin in order to avoid a possible misinterpretation of the
Table 2–10: Read-modify-write instructions
Micronas
Port
P4(1)
P4(2)
P4(3)
P4(4)
P4(7)
1)
Mnemonic
ANL
ORL
XRL
JBC
CPL
INC
DEC
DJNZ
MOV PX.Y, C
CLR PX.Y
SET PX.Y
1)
latch.
The instruction reads the port Byte (all 8 bits), modifies the addressed bit, then writes the new Byte back to the
Not available in PSDIP52-2
1)
1)
1)
1)
I/O
I/O
I/O
I/O
I/O
I/O
1)
Default
Function
A18
Port pin
Port pin
A19
Port/VS in
Toggle
Control bit
CSCR1(A18_P4_1)
CSCR1(ENARW)
CSCR1(ENARW)
CSCR1(A19_P4_4)
CSCR0(VS_OE,
P4_7_ALT)
Description
Logical AND
Logical OR
Logical EX – OR
Jump if bit = 1 and clear bit
Complement bit
Increment
Decrement
Decrement and jump if not zero
Move carry bit to bit Y of Port X
Clear bit Y of Port X
Set bit Y of Port X
Alternate Function 2
Sept. 10, 2004; 6251-556-3DS
Function
Function
Port pin
Read signal
Write signal
Port pin
VS output
voltage level at the pin. For example, a port bit might
be used to drive the base of a transistor. If a ‘one’ is
written to the bit, the transistor is turned on.
If the CPU would read back the status of the same port
bit from the pin rather than the latch, it would read the
base-emitter voltage of the transistor and interpret it as
a logic ‘0’. Reading the latch rather than the pin will
return the correct value of logic ‘1’.
Toggle
Control bit
–
–
–
–
CSCR0
(VS_OE,
P4_7_ALT)
Example
ANL P1, A
ORL P2, A
XRL P3, A
JBC P1.1, LABEL
CPL P3.0
INC P1
DEC P1
DJNZ P3, LABEL
MOV P1.7, C
CLR P2.6
SET P3.5
Alternate Function 3
SDA 55xx
Function
Function
–
–
–
–
OddEven out-
put
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