SDA5252 SIEMENS [Siemens Semiconductor Group], SDA5252 Datasheet - Page 91

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

The registers RELH and RELL (SFR-address E2
CAPH and CAPL (SFR-addresses E4
registers. The reset value of these registers is undefined.
6.3.10
The serial port is full duplex, meaning it can transmit and receive simultaneously. It is
also receive-buffered, meaning it can commence reception of a second byte before a
previously received byte has been read from the receive register (however, if the first
byte still hasn't been read by the time reception of the second byte is complete, one of
the bytes will be lost). The serial port receive and transmit registers are both accessed
at special function register SBUF. Writing to SBUF loads the transmit register, and
reading SBUF accesses a physically separate receive register.
The frequencies and baud rates described in this chapter depend on the internal system
clock, used by the serial interface. The internal system clock frequency of the serial
interface is defined by the oscillator frequency f
Advanced
Chapter “Advanced Function Register” on page 115).
The serial port can operate in 4 modes:
Mode 0:
Mode 1:
Mode 2:
Mode 3:
Semiconductor Group
Serial Interface
Serial data enters and exits through RxD (P3.6). TxD (P3.7) outputs the shift
clock.
10 bits are transmitted (through TxD) or received (through RxD): a start
bit (0), 8 data bits (LSB first), and a stop bit (1). On reception, the stop bit
goes into RB8 in special function register SCON. The baud rate is variable.
11 bits are transmitted (through TxD) or received (through RxD): a start
bit (0), 8 data bits (LSB first), a programmable 9th data bit, and a stop bit (1).
On transmission, the 9th data bit (TB8 in SCON) can be assigned the value
of 0 or 1. Or, for example, the parity bit (P, in the PSW) could be moved into
TB8. On reception, the 9th data bit goes into RB8 in the special function
register SCON, while the stop bit is ignored. The baud rate is programmable
via SFR-Bit SMOD.
11 bits are transmitted (through TxD) or received (through RxD): a start
bit (0), 8 data bits (LSB first), a programmable 9th data bit and a stop bit (1 ).
In fact, mode 3 is the same as mode 2 in all respects except the baud rate.
The baud rate in mode 3 is variable.
Function
Register
AFR
H
of
91
and E3
the
OSC
H
H
special
and E1
) are the corresponding capture
and the setting of bit CDC in the
H
) are the reload registers,
function
registers
SDA 525x
1998-04-08
(see