Fujitsu FR81S Manual Do Utilizador
CHAPTER 40: MULTI-FUNCTION SERIAL INTERFACE
6. Operation of CSIO
FUJITSU SEMICONDUCTOR LIMITED
CHAPTER : MULTI-FUNCTION SERIAL INTERFACE
FUJITSU SEMICONDUCTOR CONFIDENTIAL
194
[2] Slave operation (Set SCR:MS=1, SMR:SCKE=0, SCSCR:CSEN0=0.)
Transmission operation
(1) With serial data output enabled (SMR:SOE=1) and transmission operation enabled (SCR:TXE=1),
writing transmission data to TDR sets SSR:TDRE=0. This resulted in output the transmission data in
synchronization with a falling edge of the serial clock (SCK) input.
(2) Outputting the transmission data in the first bit sets SSR:TDRE=1 and, if the transmission interrupt is
enabled (SCR:TIE=1), outputs a transmission interrupt request. At this time, the transmission data in the
second byte can be written.
Reception operation
(1) With serial data output disabled (SMR:SOE=0) and reception operation enabled (SCR:RXE=1), the
reception data is sampled at a rising edge of the serial clock input (SCK).
(2) Receiving the last bit sets SSR:RDRF=1. When the reception interrupt is enabled (SCR:RIE=1), a
reception interrupt request will be generated.
At this time, the receive data (RDR) can be read.
(3) Reading the receive data (RDR) clears SSR:RDRF to "0".
Transmission/Reception operation
(1) To perform transmission and reception at the same time, enable serial data output (SMR:SOE=1) and
enable transmission/reception operation (SCR:TXE, RXE=1).
(2) When transmission data is written in TDR, SSR:TDRE=0 is set, and the transmission data is output in
synchronization with the falling edge of serial clock (SCK) input. When transmission data of the first bit
is output, SSR:TDRE=1 is set, and when transmission interrupt is enabled (SCR:TIE=1), a transmission
interrupt request is output. At this time, the transmission data of the second byte can be written.
(3) Receive data is sampled by the rising edge of serial clock (SCK) input. When the last bit of receive data is
received, SSR:RDRF=1 is set, and when reception interrupt is enabled (SCR:RIE=1), a reception
interrupt request is output. At this time, receive data (RDR) can be read. When receive data is read,
SSR:RDRF is cleared to "0".
MB91520 Series
MN705-00010-1v0-E
1507