Ricoh R5C841 - Manual (Page 42)

R5C841 PCI-CardBus/IEEE 1394/SD Card/Memory Stick/xD/ExpressCard Data Sheet
12345  2004 R EV .1.10 4-17
4.19.1 Protocol
The R5C841 accesses to the xD Picture Card through the 32-bit Data port register. Writing to the
Data port register can transfer address, command and data to the xD Picture Card. The data
transfer to the xD Picture Card enables in units of 8-bit, 16-bit or 32-bit. On the 16-bit or 32-bit
access, the R5C841 can access to the xD Picture Card by increments of 8-bit unit automatically.
Note that only lower 1byte works when write of address and command data.
4.20 Serial ROM Interface
The R5C841 can load data for Subsystem ID, Subsystem Vendor ID (the PCI Interface) and
some PCI configuration registers default value from the Serial ROM (I 2 C BUS). After that, the
R5C841 can set them to each register automatically.
• I 2 C BUS  is registered trademark of PHILIPS ELECTRONICS N.V.
Purchase of Ricoh’s I 2 C components conveys a license under the Philips I 2 C patent to use the
components of the I 2 C system, provided the system conforms to the I 2 C specifications defined by
Philips.
4.20.1 Outline
The R5C841 supports 100k mode and 7-bit address, and automatically stores the data (See.
Chapter 4.20.3) from the Serial ROM when the first PCI Reset is deasserted after deassertion of
the GBRST#.
4.20.2 User’s Setting
Connecting the SPKROUT pin to a pull-down resistor of 100k Ω enables the use of the Serial
ROM. When the first PCI Reset is deasserted, the R5C841 starts to sample SPKROUT pin.
When SPKROUT pin is connected to a pull-down resistor of 100k Ω , the R5C841 attempts to load
data through the Serial ROM. In this case, UDIO3 is reassigned to SCL (the clock signal) and
UDIO4 is reassigned to SDA (the data signal). The SDA and the SCL must be connected to
VCC_3V through pull-up resistors of 10k Ω . When the SPKROUT pin is connected to VCC_3V
through a pull-up resistor of 100k Ω , the R5C841 does not load data through the Serial ROM. See
the PC Card Misc Control 4 register for setting of UDIO3 and UDIO4.
R5C841
SPKROUT
UDIO4
UDIO3
SPKROUT
UDIO4
UDIO3
R5C841
SDA SCL
UDIO4
UDIO3
Serial ROM
Without the Serial ROM With the Serial ROM
VCC_3V
10k Ω
VCC_3V
100k Ω
10k Ω
100k Ω