MITSUBISHI MICROCOMPUTERS
M37270MF-XXXSP
M37270EF-XXXSP, M37270EFSP
SINGLE-CHIP 8-BIT CMOS MICROCOMPUTER with CLOSED CAPTION DECODER
and ON-SCREEN DISPLAY CONTROLLER
(4) Clock for OSD
As a clock for display to be used for OSD, it is possible to select one
of the following 3 types.
Data slicer clock output from the data slicer (approximately 26 MHz)
•
0
7
Clock from the LC oscillator supplied from the pins OSC1 and OSC2
•
Clock source control register
(CS : address 021616
Clock from the ceramic resonator or the quartz-crystal oscillator
•
)
from the pins OSC1 and OSC2
This OSD clock for each block can be selected by the following bits
: bit 7 of the port P3 direction register, bits 5 and 4 of the clock source
control register (addresses 021616). A variety of character sizes can
be obtained by combining dot sizes with OSD clocks. When not us-
ing the pins OSC1 and OSC2 for the OSD clock I/O pins, the pins
can be used as sub-clock I/O pins or port P6.
CC mode clock selection bit
0 : Data slicer clock
1 : OSC1 clock
OSD mode clock selection bits
b2 b1
0
0
1
1
0 : Data slicer clock
1 : OSC1 clock
0 :
Do not set
1 :
Table 13. Setting for P63/OSC1/XCIN, P64/OSC2/XCOUT
EXOSD mode clock selection bit
0 : Data slicer clock
1 : OSC1 clock
OSD clock
I/O pin
Sub-clock
I/O pin
Input
port
Function
Register
OSD1 oscillating mode selection bits
b5 b4
b7 Port P3 direction
register
0
0
1
0
0
1
1
0 : 32 kH
1 : Input ports P6
0 : LC oscillating mode
Z
oscillating mode
3
, P6
4
Clock source
control register
0
1
1
0
1
1
0
0
0
1
b5
b4
1 : Ceramic quartz-crystal
•
oscillating mode
Pre-divide ratio of layer 2 selection bit
0 : ✕ 1
1 : ✕ 2
Test bit (Note)
Note : Be sure to set bit 7 to “0” for program of the mask and the
EPROM versions. For the emulator MCU version
(M37270ERSS), be sure to set bit 7 to “1” when using the
data slicer clock for software debugging.
Fig. 59. Structure of clock control register
Data slicer clock
“0”
Data slicer
circuit
CC mode block
CS0
“1”
“0”
“00”
32 kHZ
OSD mode block
OSC1 clock
CS1
CS2 = “0”
“1”
“0”
“10”
LC
CS5, CS4
“11”
Ceramic •
quartz-crystal
EXOSD mode block
CS3
“1”
Oscillating mode for OSD
Fig. 60. Block diagram of OSD selection circuit
52
RENESAS [ RENESAS TECHNOLOGY CORP ]
