EM77950
BB Controller
9.6 Function Description
9.6.1 Block Diagram Description
The following subsections describe the function of each blocks and signals. Fig. 9.2
depicts how the SPI communication is carried out.
SDI: Serial Data In
SCK: Serial clock
SDO: Serial Data Out
RBFIF: Set by Buffer Full Detector, and reset by software
SPIS: Loads the data in SPIWB register, and begin to shift
Shift reg.: Shifting byte out and in. The order is defined by bit SDOD. Both the Shift
register and the SPIWB registers are loaded at the same time. Once data
are written to, SPIS starts transmission / reception. The received data will be
moved to the SPIRB register, as the shifting of the 8-bit data is completed.
The RBFIF (Read Buffer Full) flag is equal to 1.
SPIRB: Read buffer. The buffer will be updated, as the 8-bit shifting is completed. The
data must be read before the next reception is finished. The RBF flag is
cleared as the SPIRB register is read.
SPIWB: Write buffer. The buffer will deny any write until the 8-bit shifting is completed.
The SPIS bit will be kept in 1 if the communication is still undergoing. This
flag must be cleared as the shifting is finished. Users can determine if the
next write attempt is available.
SBR2~SBR0: Programming the clock frequency/rates and sources.
Edge Select: Selecting the appropriate clock edges by programming the CES bit.
9.6.2 Signal & Pin Description
The three pins, SDI, SDO, and SCK, which are shown in Fig. 9-1, will be explained in
details as follows:
SDI:
SDI: Serial Data In
Serial Data In
Receive serially
Defined as high-impedance, if not selected.
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Product Specification (V1.0) 10.09.2007
(This specification is subject to change without further notice)
ELAN [ ELAN MICROELECTRONICS CORP ]
