- SS-HQ1 Application Notes -
Ver.1.0.0 January 7, 2005
205
ECK-28MHz INT / ECK-27MHz LL Switching System (manual setting)
This system switches between LL and INT depending on whether the DIP switch is set to “High” or “Low”.
INT mode operates with 28MHz ECK input. LL mode uses 27MHz ECK input.
After the DIP switch position is changed, the RESET operation must be performed, both when changing from
INT to LL, and when changing from LL to INT.
Therefore, when switching between INT and LL, first turn off the power, then change the DIP switch position,
and then turn the power back on.
A block diagram of the system is shown in
SYSSELFLG is assigned to a port in advance. See
for information on SYSSELFLG and the parameter settings that are switched according to the
SYSSELFLG value.
When switching from INT to LL (when the DIP switch is set to the “High” position), the following operations are
performed.
• SYSSELFLG, which is assigned to a specified port, is set to 1[h] to switch MODESEL/SGMODE to the LL setting.
• The MCK switching circuit is switched to the VCO position (MCK clock supply).
• The ECK switching circuit is switched to the 27MHz position (ECK 27MHz clock supply).
When switching from LL to INT (when the DIP switch is set to the “Low” position), the following operations are
performed.
• SYSSELFLG, which is assigned to a specified port, is set to 0[h] to switch MODESEL/SGMODE to the INT setting.
• The MCK switching circuit is switched to the GND position (MCK clock supply stopped).
• The ECK switching circuit is switched to the 28MHz position (ECK 28MHz clock supply).
Fig 12.2-14 ECK-28MHz INT/ECK-27MHz LL Switching System Block Diagram
* Do not assign SGMODE to a port.
CXD3172AR
ESCI
MC
K
27MHz
(X'tal)
VCO
(LC)
LPF
(V-PLL)
EXT-VD
86
ESCO
87
ECK
88
PCOMP
42
43
S0
44
S1
46
EXVIDEOY
EXVIDEO
58
57
3.3V
INT : L
LL : H
3.3V
28MHz
(X'tal)
INT mode
LL mode
Pn
*
1
SYS
SEL
F
LG
INT/LL Change signal
LL mode
INT mode
XRST
11
Reset
Circuit
DIPSW
"H"
"L"
"H"
"L"