DS80C320-MCG Datasheet, PDF (140/175 Pages) Dallas Semiconductor – High-Speed Microcontroller User Guide

High-Speed Microcontroller User’s Guide
SERIAL PORT SCON0; 98h
CONTROL ZERO
This is the standard 80C32 Serial Port. The new Serial Port is designated Serial Port 1 and is documented
below.
SCON0.7
SM0/FE_0 - Serial Port 0 Mode bit 0 or Framing Error Flag.
PCON.6 (SMOD0) determines whether this bit functions as SM0 or
FE. The operation of SM0 (SMOD0 = 0) is described in the table
below. When SMOD0 = 1, the serial port will set FE to indicate an
invalid stop bit. When used as FE, this bit must be cleared in
software.
SCON0.6
SM1_0 - Serial Port 0 mode select 1. The operation of SM1 is
described in the table below. SCON0.5 SM2_0 - Multiple MCU
communication. Setting this bit to a one enables multiprocessor
communication in Modes 2 or 3. If the ninth bit is 0, the RI_0 will
not be set. In Mode 1, setting the SM2_0 bit to a one causes the
RI_0 bit not to be set if a valid stop bit is not received. In the High-
Speed Microcontroller, SM2_0 also has a new function. In mode 0,
the SM2_0 bit controls whether the serial port clock runs at a divide
by 4 or a divide by 12 of the oscillator when not in PMM. When set
to a logic 0, the serial port runs at a divide by 12. When set to a
logic one, the serial port runs at a divide by 4. This results in much
faster synchronous serial communication.
SCON0.4
REN_0 - Receive Enable. When set to a 1, the receive shift register
will be enabled.
SCON0.3
TB8_0 - Set/clear to define the state of the ninth transmission data
bit in modes 2 and 3.
SCON0.2
RB8_0 - Indicates the state of an incoming ninth bit when in modes
2 and 3. In mode 1, when SM2 =0, RB8_0 is the state of the stop
bit received. RB8_0 is not used in mode 0. SCON0.1 TI_0 - Flag
that indicates the transmitted word has been completely shifted out.
In mode 0, TI_0 is set at the end of the eighth data bit. In all other
modes, this bit is set at the end of the last data bit. It must be cleared
manually by software.
SCON0.0
RI_0 - Flag that indicates a serial word has been received. In mode
0, RI_0 is set at the end of the eighth bit. In mode 1, it is set after the
last sample of the incoming stop bit subject to the state of SM2_0.
In modes 2 and 3, RI_0 is set after the last sample of RB8_0. It must
be cleared manually by software.
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