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Semiconductor Group
110
On-Chip Peripheral Components
7.9
System Clock Output
For peripheral devices requiring a system clock, the SAB 80(C)515/80(C)535 provides a clock
output signal derived from the oscillator frequency as an alternate output function on pin P1.6/
CLKOUT. lf bit CLK is set (bit 6 of special function register ADCON, see figure 7-53), a clock signal
with 1/12 of the oscillator frequency is gated to pin P1.6/CLKOUT. To use this function the port pin
must be programmed to a one (1), which is also the default after reset.
Figure 7-53
Special Function Register ADCON (Address 0D8H)
The system clock is high during S3P1 and S3P2 of every machine cycle and low during all other
states. Thus, the duty cycle of the clock signal is 1:6. Associated with a MOVX instruction the
system clock coincides with the last state (S3) in which a RD or WR signal is active. A timing
diagram of the system clock output is shown in figure 7-54.
Bit
Function
CLK
Clockout enable bit. When set, pin P1.6/CLKOUT outputs the system
clock which is 1/12 of the oscillator frequency.
These bits are not used in controlling the clock out functions.
0DFH 0DEH 0DDH 0DCH 0DBH 0DAH 0D9H 0D8H
BD
CLK
–
BSY
ADM
MX2
MX1
MX0
0D8H
ADCON
*
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 ...