SDA5252 SIEMENS [Siemens Semiconductor Group], SDA5252 Datasheet - Page 45

• Manufacturer Part Number: SDA5252
• Description: TVTEXT 8-Bit Microcontroller
• Manufacturer: SIEMENS [Siemens Semiconductor Group]

SDA 525x
Stack Pointer (SP)
The 8-bit stack pointer contains the address at which the last byte was pushed onto the
stack. This is also the address of the next byte that will be popped. The SP is
incremented during a push. SP can be read or written to under software control. The
stack may be located anywhere within the internal data RAM address space and may be
as large as 256 bytes.
Data Pointer Register (DPTR)
The 16-bit Data Pointer Register DPTR is the concatenation of registers DPH (high-
order byte) and DPL (low-order byte). The DPTR is used in register-indirect addressing
to move program memory constants and to access the extended data memory. DPTR
may be manipulated as one 16-bit register or as two independent 8-bit registers DPL and
DPH.
Eight data pointer registers are available, the active one is selected by a special function
register (DPSEL).
Port 0, Port 1, Port 2, Port 3, Port 4
The five ports provide 26 I/O-lines and 5 input-lines to interface to the external world. All
five ports are both byte and bit addressable. Port 0 is used for binary l/O and as clock
2
and data line of a software driven I
C bus. Port 1 provides eight PWM- output channels
as alternate functions while port 2.0 - 2.3 are digital or analog inputs. Port 3 contains
special control signals. Port 4 will usually be selected as memory extension interface
(ROM-less version only).
Interrupt Logic
Controlled by three special function registers (IE, IP0 and IP1) the interrupt logic
provides several interrupt vectors. Each of them may be assigned to high or low priority
(see Chapter “Interrupt System” on page 62).
Timer/Counter 0/1
Two general purpose 16-bit timers/counters are controlled by the special function
registers TMOD and TCON (see Chapter “General Purpose Timers/Counters” on
page 80).
Serial Interface
A full duplex serial interface is provided where one of three operation modes may be
selected. The serial interface is controlled by two special function registers (SCON,
SBUF) as described in Chapter “Serial Interface” on page 91.
Semiconductor Group
45
1998-04-08