SAB82532 Datasheet, PDF (72/272 Pages) Siemens Semiconductor Group – ICs for Communications

SAB 82532/SAF 82532
Asynchronous Serial Mode
Transmitter Status Bit
The status bit ‘Flow Control Status’ (STAR:FCS) indicates the current state of the
transmitter, as follows:
0: if the transmitter is in XON state,
1: if the transmitter is in XOFF state.
Note: The transmitter cannot be turned off by software without disrupting data possibly
remaining in the XFIFO.
Flow Control for Received Data
After writing a character value to register TIC (Transmit Immediate Character) its
contents are inserted in the outgoing character stream
• immediately upon writing this register by the microprocessor if the transmitter is in
IDLE state. If no further characters (XFIFO contents) are to be transmitted, i.e. the
transmitter returns to IDLE state after transmission of TIC, an ALLS (All Sent) interrupt
will be generated.
• after the end of a character currently being transmitted if the transmitter is not in IDLE
state. This does not affect the contents of the XFIFO. Transmission of characters from
XFIFO is resumed after the contents of register TIC are shifted out.
Transmission via this register is possible even when the transmitter is in XOFF state
(however, CTS must be ‘low’).
The TIC register is an eight-bit register. The number of significant bits is determined by
the programmed character length (right justified). Parity value (if programmed) and
selected number of stop bits are automatically appended, similar to the characters
written in the XFIFO. The usage of TIC is independent of flow control, i.e. is not affected
by bit MODE:FLON.
To control access to register TIC, an additional status bit STAR:TEC (TIC Executing) is
implemented which signals that transmission command of currently programmed TIC is
accepted but not completely executed. Further access to register TIC is only allowed if
bit STAR:TEC is ‘0’.
6.4.3 Selectable Out-of-band Flow Control for Transmitter and Receiver (V3.x)
Transmitter
The transmitter output is enabled if CTS signal is ‘LOW’ OR the recognition of the XON
characters (if MODE:FLON = ‘1’). If the MODE:FLON = ‘0’, then the transmitter is only
enabled when the CTS signal is ‘LOW’. Setting the MODE:FCTS = ‘1’ allows the
transmitter to send data independent of the condition of the CTS signal, the
in-band flow control (XON/XOFF) method would still be operational if MODE:FLON = ‘1’.
Semiconductor Group
72
07.96