SH7727 Datasheet, PDF (609/1109 Pages) Renesas Technology Corp – Renesas 32-Bit RISC Microcomputer SuperH RISC engine Family/SH7700 Series

Section 17 Serial Communication Interface (SCI)
Start transmission/reception
Read TDRE bit in SCSSR
(1)
No
TDRE = 1?
Yes
Write transmission data to SCTDR
and clear TDRE bit in SCSSR to 0
Read ORER bit in SCSSR
ORER = 1?
No
Yes
(2)
Error processing
Read RDRF bit in SCSSR
(3)
No
RDRF = 1?
Yes
Read receive data of SCRDR ₍₄₎
and clear RDRF bit in SCSSR to 0
No
All data
transmitted/received?
Yes
Clear TE and RE bits
in SCSCR to 0
End transmission/reception
(1) SCI status check and transmit
data write:
Read the serial status register
(SCSSR), check that the TDRE bit
is 1, then write transmit data in the
transmit data register (SCTDR)
and clear TDRE to 0. The TXI
interrupt can also be used to
determine if the TDRE bit has
changed from 0 to 1.
(2) Receive error processing:
If a receive error occurs, read the
ORER bit in SCSSR to identify the
error. After executing the
necessary error processing, clear
ORER to 0. Transmitting/receiving
cannot resume if ORER remains
set to 1.
(3) SCI status check and receive data
read:
Read the serial status register
(SCSSR), check that RDRF is set
to 1, then read receive data from
the receive data register (SCRDR)
and clear RDRF to 0. The RXI
interrupt can also be used to
determine if the RDRF bit has
changed from 0 to 1.
(4) To continue transmitting and
receiving serial data:
Read the RDRF bit and SCRDR,
and clear RDRF to 0 before the
frame MSB (bit 7) of the current
frame is received. Also read the
TDRE bit to check whether it is
safe to write (if it reads 1); if so,
write data in SCTDR, then clear
TDRE to 0 before the MSB (bit 7)
of the current frame is transmitted.
Note: When switching transmit or receive operation to simultaneous serial transmit and receive
operations, first clear the TE bit and RE bit to 0, and then set both these bits to 1
simultaneously.
Figure 17.23 Sample Flowchart of Simultaneous Serial Transmit and Receive Operations
Rev. 5.00 Dec 12, 2005 page 537 of 1034
REJ09B0254-0500