SAB80C517-M16 SIEMENS [Siemens Semiconductor Group], SAB80C517-M16 Datasheet - Page 149

• Manufacturer Part Number: SAB80C517-M16
• Description: 8-Bit CMOS Single-Chip Microcontroller
• Manufacturer: SIEMENS [Siemens Semiconductor Group]

7.10
For peripheral devices requiring a system clock, the SAB 80C517 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 ADCON0, see figure 7-68), 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 7-68
Special Function Register ADCON0 (Address 0D8 H )
Bit
CLK
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 7-69.
Note:
During slow-down operation (see section 7.7) the frequency of the clockout signal is divided by
eight.
Semiconductor Group
0D8 H
System Clock Output
0DF H
BD
These bits are not used in controlling the clock out functions.
0DE H
CLK
Function
Clockout enable bit. When set, pin P1.6/CLKOUT outputs the system
clock which is 1/12 of the oscillator frequency.
0DD H 0DC H
ADEX
BSY
150
0DB H
ADM
On-Chip Peripheral Components
0DA H
MX2
0D9 H
MX1
0D8 H
MX0
ADCON0