Samsung SCX-1150F Repair Manual page 14

3-3-2-3 EXTERNAL DMA part
The function of this part is to bring data from external
DEVICE(OASIS:U21) by using GENERAL DMA. If DMA
REQUEST(/IP_REQ) is sent from external DEVICE to
S3C46MOX(JUPITER3:U15), DMA ACKNOWLEDGE
SIGNAL(/IP_ACK) is activated and the GENERAL DMA is
driven, so READ STROBE(/RD) in the external DEVICE to
bring data from the external DEVICE requiring CHANNEL.
To transfer this DATA to the DESTINATION MEMORY, the
ADDRESS of the DESTINATION MEMORY, CHIP
SELECT and WRITE STROBE(/WR) are generated to
store.
That is, if the EXTERNAL DMA is required by the external
DEVICE, S3C46MOX(Jupiter3:U15) responds to drive the
inside DMA CONTROLLER and then allocate GENERAL
DMA to external CHANNEL so that the data may be trans-
ferred to MEMORY TO MEMORY or external DEVICE TO
MEMORY.
• For more details, see the circuit description, see the circuit
description part of IMAGE PROCESSOR (5.3).
3-3-2-4 DRAM control part
Since S3C46MOX(Jupiter3) has the DRAM CON-
TROLLER build-in, it may be used by connecting DRAM
with external memory.
The Control mode of DRAM CONTROLLER provided by
S3C46MOX(Jupiter3) is available for EARLY WRITE,
NORMAL READ, PAGE MODE, and BYTE/HALF WORD
ACCESS, and is supported even by EDO DRAM,and
SDRAM as well as, Fast page DRAM.
This system uses SDRAM, and the signal used for
READ/WRITE uses /RD,/WR signal used for SYSTEM
BUS CONTROL. It is supported with auto REFRESH and
also by the Self-refresh mode for DRAM BACK UP. It con-
sists of 2 Banks connected to common /SCS[1:0], /SCAS,
/SRAS, /SCLK, /SCKE, /DQM[1:0], each of them may use
up to 2M ~ 32M HALF WORD.
In this system, 2 MB is applied as system memory. The
area of DRAM is specified in the DRAM MEMORY MAP of
Fig. 1, while the related TIMING DIAGRAM in Fig. 5, 6, 7,
8, 9.
3-3-2-5 RTC (REAL TIME CLOCK) part
RTC Circuit is logic for maintaining information of the cur-
rent time, and it is operated in both conditions, Primary
Power and Battery Back-up. Additional RTC IC is not used
because RTC is built-in at MFP Controller.
RTC Logic at inner part of ASIC accepts Crystal
(32.768KHz:X3), which is inputted from outside, as a Clock
Source, and it divides the Clock by every minute for mak-
Samsung Electronics
CIRCUIT DESCRIPTION
ing hour, minute, second, year, month, and day. While the
power is on and the Crystal is being oscillation, the RTC
Logic independently counts the time without control by
Software and marks the value of hour, minute, second,
year, month, and day at the appropriated Register.
Software confirms the value of the Register and displays it
at LCD.
3-3-2-6 PARALLEL PORT INTERFACE division
S3C46MOX(Jupiter3) has the Parallel Port Interface part
enabling Parallel Interface with PC.
This part is connected to PC through Centronics Connector
in this system, which consists of /ERROR, PE, BUSY,
/ACK, SLCT, /INIT, /SLCTIN, /AUTOFD, /STB and 245DIR
as the part generating the main control signal used to drive
PARALLEL COMMUNICATION. Data transmission
method between this part and PC supports the method
specified in P1284
(http://www.fapo.com/ieee1284.html) of IEEE.
That is, the Compatibility mode, the fundamental transmis-
sion method of print data, supports the Nibble Mode(4bits
data) supporting the Data Uploading to PC, Byte
Mode(8bits data), and ECP(Enhanced Capabilities Port : 8
bits data transmission & receiving) supporting two-way
high speed transmission to PC. The Compatibility mode
and ECP mode may be simply explained as follows.
The Compatibility mode is generally called Centronics
mode and is the protocol used for transmitting data by most
of PC. The ECP mode provides two-way high speed com-
munication as the protocol suggested for improved com-
munication with peripheral equipments such as printer and
scanner.
The ECP mode provides two types of cycles in two-way
transmission. They are data and command cycles.
Command cycle again has Run-length count and Channel
addressing types.
First, RLE (Run Length Encoding) type, having 64-fold
compressibility, is available for the real time data compres-
sion, and is used usefully for printer and scanner, which
have to transmit large capacity of raster image having a
series of same data. Next, Channel Addressing is pro-
posed for addressing single structure of multi-device.
For example, although the printer channel is processing
the printer image when the fax/printer/scanner have one
structure like this system, they may use parallel port for
another use. This system does not apply to the parallel port
Interface.
Parallel Port Standard
Repair Manual
3-11