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Semiconductor Group
51
On-Chip Peripheral Components
Mode 0
The baud rate in mode 0 is fixed:
Mode 2
The baud rate in mode 2 depends on the value of bit SMOD in special function register PCON (see
figure 7-9). If SMOD = 0 (which is the value after reset), the baud rate is 1/64 of the oscillator
frequency. If SMOD = 1, the baud rate is 1/32 of the oscillator frequency.
Figure 7-9
Special Function Register PCON (Address 87H)
Modes 1 and 3
In these modes the baud rate is variable and can be generated alternatively by a dedicated baud
rate generator or by timer 1.
Using the baud rate generator:
In modes 1 and 3, the SAB 80(C)515 can use the internal baud rate generator for the serial
interface. To enable this feature, bit BD (bit 7 of special function register ADCON) must be set (see
figure 7-10). This baud rate generator divides the oscillator frequency by 2500. Bit SMOD
(PCON.7) also can be used to enable a multiply by two prescaler (see figure 7-9). At 12-MHz
oscillator frequency, the commonly used baud rates 4800 baud (SMOD = 0) and 9600 baud (SMOD
= 1) are available. The baud rate is determined by SMOD and the oscillator frequency as follows:
Bit
Function
SMOD
When set, the baud rate of serial interface in modes 1, 2, 3 is doubled.
Mode 0 baud rate =
oscillator frequency
12
Mode 2 baud rate =
oscillator frequency
64
2
SMOD
x
SMOD
PDS
IDLS
–
GF1
GF0
PDE
IDLE
87H
PCON
These bits are not used in controlling serial interface.
Mode 1, 3 baud rate =
oscillator frequency
2500
2
SMOD
x
*
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 ...