HD404669 Datasheet, PDF (42/142 Pages) Hitachi Semiconductor – Low-Voltage AS Microcomputers with On-Chip DTMF Generation Circuit

HD404669 Series
System clock select register 1 (SSR1: $029)
Bit
Initial value
Read/Write
Bit name
3
0
W
SSR13
2
0
W
SSR12
1
0
W
SSR11
0
0
W
SSR10
SSR13 32-kHz oscillation stop
0 Oscillation operates in stop mode
1 Oscillation stops in stop mode
32-kHz oscillation division
SSR12 ratio selection
0
f_SUB = f_X/8
1
f_SUB = f_X/4
System clock
SSR23 SSR22 SSR11 SSR10 ^selection
0
0
0
0 400 kHz
1 800 kHz
1
0 2 MHz
1 4 MHz
1
×
× 3.58 MHz
1
0
1
1 8 MHz
1
×
× 7.16 MHz
Note: SSR13 is cleared only by a RESET input. SSR13 will not be cleared by a STOPC input during
stop mode, and will retain its value.
SSR13 will also not be cleared upon entering stop mode.
Figure 24 System Clock Select Register 1 (SSR1)
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
SSR23
0
1
SSR22
0
1
0
1
System clock selection*²
Selected from 400 kHz,
800 kHz, 2 MHz, 4 MHz
3.58MHz
8MHz
7.16MHz
SSR21
0
1
SSR20
0
1
0
1
System clock division
ratio selection*¹
Division by 4
Division by 8
Division by 16
Division by 32
Notes : *1 The DTMF generation circuit frequencies are not affected by the system clock division ratio
setting.
*2 See system clock select register 1 (SSR1).
Figure 25 System Clock Select Register 2 (SSR2)
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