HD404669 Datasheet, PDF (95/142 Pages) Hitachi Semiconductor – Low-Voltage AS Microcomputers with On-Chip DTMF Generation Circuit

System clock select register 1 (SSR1: $029)
Bit
Initial value
Read/Write
Bit name
3
0
W
SSR13*¹
2
0
W
SSR12
1
0
W
SSR11
0
0
W
SSR10
HD404669 Series
SSR12
0
1
SSR13
0
1
32 kHz division ratio switch
f_SUB=f_X/8
f_SUB=f_X/4
32 kHz oscillation stop setting
Oscillation continues in stop mode
Oscillation stops in stop mode
SSR23 SSR22 SSR11 SSR10 System clock selection
0
0
0
0
400kHz
1
800 kHz
1
0
2 MHz
1
4 MHz
1
×
×
3.58 MHz
1
0
1
1
8 MHz
1
×
×
7.16 MHz
× : Don't care
System clock select register 2 (SSR2: $02A)
Bit
Initial value
Read/Write
Bit name
3
0
W
SSR23
2
0
W
SSR22
1
0
W
SSR21
0
0
W
SSR20
SSR21
0
1
SSR20
0
1
0
1
System clock division ratio selection*²
Division by 4
Division by 8
Division by 16
Division by 32
Notes: 1. SSR13 is cleared to 0 only by RESET input. In the case of STOPC input in stop mode it
retains its current value. SSR13 is not reset in stop mode
2. The DTMF generation circuit frequencies are not affected by the system clock division ratio
setting.
Figure 73 System Clock Select Register 1 and 2 (SSR1, SSR2)
95