EM78451AP EMC [ELAN Microelectronics Corp], EM78451AP Datasheet - Page 24

• Manufacturer Part Number: EM78451AP
• Description: 8-Bit Microcontroller
• Manufacturer: EMC [ELAN Microelectronics Corp]

EM78451
8-Bit Microcontroller
20 •
SPIC
The following describes the function of each block and explains how to carry out the
SPI communication with the signals depicted in Fig.11 and Fig.12:
2 1 0
P92/SDI: Serial Data In.
P93/SDO: Serial Data Out.
P94/SCK: Serial Clock.
P95//SS: /Slave Select (Option). This pin (/SS) may be required during a slave
RBF: Set by Buffer Full Detector, and reset in software.
RBIF:Set by Buffer Full Detector, and reset in software.
Buffer Full Detector: Sets to 1, when an 8-bit shifting is completed.
SSE:Loads the data in SPIS register, and begin to shift
SPIS reg.: Shifting byte in and out. The MSB is shifted first. Both the SPIS and
SPIR reg.: Read buffer. The buffer will be updated as the 8-bit shifting is
SPIW reg.: Write buffer. The buffer will deny any attempt to write until the 8-bit
mode.
SPIW registers are loaded at the same time. Once the data are written, SPIS starts
with the transmission / reception. The data received will be moved to the SPIR
register, as the shifting of the 8-bit data is completed. The RBF (Read Buffer Full)
flag and the RBFI (Read Buffer Full Interrupt) flag are then set.
completed. The data must be read before the next reception is finished. The RBF
flag is cleared as the SPIR register reads.
shifting is completed.
Fig. 12 The Function Block Diagram of SPI Transmission
SPIWB
7~0
T1CON
DATA BUS
FOSC
1 0
SDO
(This specification is subject to change without further notice)
SPIC
SPI Shift Buffer
7
6 4
SPIS
SPI
Product Specification (V1.2) 05.27.2004
1 0
Shift Clock
2
INTC
SDI
4
SPIC
7~0
SPIRB