Epson S1C63558 - Manual (Page 94)

84 EPSON S1C63558 TECHNICAL MANUAL
CHAPTER 4: PERIPHERAL CIRCUITS AND OPERATION (Serial Interface)
(1) Write "0" in the receive enable register RXEN and
transmit enable register TXEN to reset the serial
interface.
(2) Write "1" in the receive enable register RXEN to set
into the receiving enable status.
(3) In case of the master mode, confirm the transmit ready
status on the slave side (external serial input/output
device), if necessary. Wait until it reaches the transmit
ready status.
(4) Write "1" in the receive control bit RXTRG and start
receiving.
In the master mode, this control causes the synchro-
nous clock to change to enable and is provided to the
shift register for receiving and output from the SCLK
terminal.
In the slave mode, it waits for the synchronous clock
to be input from the SCLK terminal. The received data
input from the SIN terminal is successively incorpo-
rated into the shift register in synchronization with the
rising edge of the synchronous clock.
At the point where the data of the 8th bit has been
incorporated at the final (8th) rising edge of the
synchronous clock, the content of the shift register is
sent to the receive data buffer and the receiving
complete interrupt factor flag ISRC is set to "1". When
interrupt has been enabled, a receiving complete
interrupt is generated at this point.
(5) Read the received data from TRXD0–TRXD7 using
receiving complete interrupt.
(6) Repeat steps (3) to (5) for the number of bytes of
receiving data, and then set the receive disable status
by writing "0" to the receive enable register RXEN,
when the receiving is completed.
Data receiving
End
RXEN
←
0, TXEN
←
0
No
Yes
Receiving complete ?
Received data reading
from TRXD0–TRXD7
No
Yes
ISRC = 1 ?
RXEN
←
0
RXTRG
←
1
RXEN
←
1
No
Yes
Transmitter ready ?
In case of master mode
Data receive procedure
The control procedure and operation during receiving is as follows.
Fig. 4.11.6.3 Receiving procedure in clock
synchronous mode