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Semiconductor Group
48
On-Chip Peripheral Components
In all four modes, transmission is initiated by any instruction that uses SBUF as a destination
register. Reception is initiated in mode 0 by the condition RI = 0 and REN = 1. Reception is initiated
in the other modes by the incoming start bit if REN = 1. The serial interfaces also provide interrupt
requests when a transmission or a reception of a frame has completed. The corresponding interrupt
request flags for serial interface are TI or RI, resp. See section 8 for more details about the interrupt
structure. The interrupt request flags TI and RI can also be used for polling the serial interface if the
serial interrupt is not to be used (i.e. serial interrupt not enabled).
The control and status bits of the serial channel 0 in special function register S0CON are illustrated
in figure 7-8. Figure 7-7 shows the special function register S0BUF which is the data register for
receive and transmit. The following table summarizes the operating modes of serial interface 0.
Figure 7-7
Special Function Register SCON (Address 98H)
Bit
Symbol
SM0
SM1
0
0
0
1
1
0
1
1
Serial mode 0:
Shift register mode, fixed baud rate
Serial mode 1:
8-bit UART, variable baud rate
Serial mode 2:
9-bit UART, fixed baud rate
Serial mode 3:
9-bit UART, variable baud rate
SM2
Enables the multiprocessor communication feature in modes 2 and 3. In
mode 2 or 3 and SM2 being set to 1, RI will not be activated if the
received 9th data bit (RB8) is 0. In mode 1 and SM2 = 1, RI will not be
activated if a valid stop bit has not been received. In mode 0, SM2 should
be 0.
REN
Receiver enable. Enables serial reception. Set by software to enable
reception. Cleared by software to disable reception.
TB8
Transmitter bit 8. Is the 9th data bit that will be transmitted in modes 2
and 3. Set or cleared by software as desired.
RB8
Receiver bit 8. In modes 2 and 3 it is the 9th bit that was received. In
mode 1, if SM2 = 0, RB8 is the stop bit that was received. In mode 0,
RB8 is not used.
TI
Transmitter interrupt. Is the transmit interrupt flag. Set by hardware at
the end of the 8th bit time in mode 0, or at the beginning of the stop bit
in the other modes, in any serial transmission. Must by cleared by
software.
RI
Receiver interrupt. Is the receive interrupt flag. Set by hardware at the
end of the 8th bit time in mode 0, or during the stop bit time in the other
modes, in any serial reception. Must be cleared by software.
SM0
SM1
SM2
REN
TB8
RB8
TI
RI
98H
SCON
9FH
9EH
9DH
9CH
9BH
9AH
99H
98H
*
Summary of Contents for SAB 80515 Series
Page 9: ...Semiconductor Group 9 Introduction Figure 1 2 Block Diagram ...
Page 12: ...Semiconductor Group 12 Fundamental Structure Figure 2 1 Detailed Block Diagram ...
Page 18: ...Semiconductor Group 18 Central Processing Unit Figure 3 1 Fetch Execute Sequence ...
Page 73: ...Semiconductor Group 73 On Chip Peripheral Components Figure 7 25 A D Converter Block Diagram ...
Page 83: ...Semiconductor Group 83 On Chip Peripheral Components Figure 7 33 a Timer 2 Block Diagram ...
Page 215: ...Device Specifications Semiconductor Group 215 ...
Page 217: ...Device Specifications Semiconductor Group 217 Pin Configuration P LCC 68 ...
Page 219: ...Device Specifications Semiconductor Group 219 Logic Symbol ...
Page 226: ...Device Specifications Semiconductor Group 226 Figure 1 Block Diagram ...
Page 229: ...Device Specifications Semiconductor Group 229 Figure 2 Memory Address Spaces ...
Page 239: ...Device Specifications Semiconductor Group 239 Figure 4 Block Diagram of the A D Converter ...
Page 241: ...Device Specifications Semiconductor Group 241 Figure 5 Interrupt Request Sources ...
Page 242: ...Device Specifications Semiconductor Group 242 Figure 6 Interrupt Priority Level Structure ...