Samsung SCX-1100 Service Manual page 80

3-5-2 OA-980 DESCRIPTION BY FUNC-
TIONS
3-5-2-1 Clock Control Section
Internal drive frequency operates classified into two parts.
Almost all On-chip µ Controller(8bit) Module drives by
Main_clock, and Printer Interface Section(PO) only drives
by Base_clock. Main_clock and Base_clock may be set
with frequency each desires by receiving Clock supplied
from outside by PLL Logic.
At present, system Main_clock and Base_clock are each
set in 48MHz, and may be checked at SDRAM_CLK of
SDRAM(U27). Clock supplied from outside does not use
separate crystal, but 48MHz is supplied by IP_CLK,
CLK_Out of Jupiter3(U15).
The one which pulled up Main_EXT(pin46) and
Base_EXT(pin43) is the Option using internal PLL, and, at
the time of Pull-up, it does not use internal PLL, but just use
Clock supplied to Main_CLK(pin45) and Base_CLK(pin42)
as Main_clock and Base_clock.
3-5-2-2 Internal Microcontroller
8bit RISC Microcontroller is built-in, and Address area
which Micro-controller control is 64kbyte. At the same time
when cache is built in for control of more efficient SDRAM,
it possesses Hook function, namely the internal Boot ROM
256byte required for self-initialization function, too.
0x0000 .... 0x00ff
1. Memory Map
0x0100
....
0xfbff
0xfc00 .... 0xffff
Samsung Electronics
Boot ROM
SDRAM program store
and
SDRAM stack
HW registers
- This Document can not be used without Samsung's authorization -
CIRCUIT DESCRIPTION
2. Power On/Off Reset
• Power On Reset
Depending on the signal state of Reset_L(pin35), OA-
980 may be reset in the manner of hardware. Reset is on
at "Low" state and, at "High" state, Reset is Off.
Accordingly, in order for OA-980 to operate normally,
after the System initialization, the /IP_RST of
Jupiter3(U15-31) shall be converted to "High" state. In
order for safe Hardware Reset to be accomplished, it
should be maintained in "Low" state for more than 1000
Main_clock(10uS).
• Power Off Reset
PWR_down(pin107), for SDRAM(U27) to advance to the
Self Refresh Mode Reset_L(pin35) at the Power Safe
Mode, shall advance to the Reset Mode earlier than the
minimum of 1uS. This System does not use it.
3. Hook function : Self-initialization function
In case self ROM is connected to OA-980 as in Figure (15),
although the execution file is downloaded to SDRAM, the
execution file is initialized by receiving download from
Memory. This execution file is the ROM File supporting so
that all functions of Image processing related to OA-980 as
well as register setting value required for initialization(Copy,
PC scan, MultiMediaCard Print) may operate normally.
Repair Manual
3-21