HD404629R Datasheet, PDF (103/157 Pages) Renesas Technology Corp – AS Microcomputer Incorporating a DTMF Generator Circuit

HD404629R Series
System Clock Select Register (SSR: $029): Four-bit write-only register. This register must be set to the
value specified in figure 91 depending on the frequency of the oscillator connected to the OSC₁ and OSC₂
pins. Note that if the combination of the oscillation frequency and the value in this register is different
from that specified in figure 91, the DTMF output frequencies will differ from the correct frequencies as
listed in figure 89.
System clock select register (SSR: $029)
Bit
Initial value
Read/Write
Bit name
3
0
W
SSR3
2
0
W
SSR2
1
0
W
SSR1
0
0
W
SSR0
SSR3 32-kHz oscillation stop
SSR1 SSR0 System clock selection
0
Oscillation operates in stop mode
1
Oscillation stops in stop mode
32-kHz oscillation division
SSR2 ratio selection
0
0
400 kHz
0
1
800 kHz
1
0
2 MHz
1
1
4 MHz
0
f_SUB = f_X/8
1
f_SUB = f_X/4
Note: SSR3 is cleared only by a RESET input. SSR3 will not be cleared by a STOPC input during stop
mode, and will retain its value. SSR3 will also not be cleared upon entering stop mode.
Figure 91 System Clock Select Register (SSR)
101