Datasheet

Section 13 Serial Communication Interface
REJ09B0140-0900 Rev. 9.00 Page 445 of 846
Sep 16, 2010
H8S/2215 Group
Yes
<End>
[1]
No
Initialization
Start reception
[2]
No
Yes
Read RDRF flag in SSR
[4]
[5]
Clear RE bit in SCR to 0
Error processing
(Continued below)
[3]
Read receive data in RDR, and
clear RDRF flag in SSR to 0
No
Yes
ORER = 1
RDRF = 1
All data received?
Read ORER flag in SSR
<End>
Error processing
Overrun error processing
Clear ORER flag in SSR to 0
[3]
[1] SCI initialization:
The RxD pin is automatically designated as
the receive data input pin.
[2] [3] Receive error processing:
If a receive error occurs, read the ORER
flag in SSR, and after performing the
appropriate error processing, clear the
ORER flag to 0. Transfer cannot be
resumed if the ORER flag is set to 1.
[4] SCI status check and receive data read:
Read SSR and check that the RDRF flag is
set to 1, then read the receive data in RDR
and clear the RDRF flag to 0.
Transition of the RDRF flag from 0 to 1 can
also be identified by an RXI interrupt.
[5] Serial reception continuation procedure:
To continue serial reception, before the
MSB (bit 7) of the current frame is received,
reading the RDRF flag, reading RDR, and
clearing the RDRF flag to 0 should be
finished. The RDRF flag is cleared
automatically when the DMAC or the DTC*
is activated by a receive data full interrupt
(RXI) request and the RDR value is read.
Note: * Clearing of the RDRF flag are
performed automatically by the DTC
when the DTC's DISEL bit is cleared to
0 and the transfer counter value is not
0. Consequently, it is necessary to use
the CPU to clear the RDRF flag if
DISEL is set to 1 or if the transfer
counter value is 0.
Figure 13.23 Sample Serial Reception Flowchart
13.6.5 Simultaneous Serial Data Transmission and Reception (Clocked Synchronous Mode)
Figure 13.24 shows a sample flowchart for simultaneous serial transmit and receive operations.
The following procedure should be used for simultaneous serial data transmit and receive
operations. To switch from transmit mode to simultaneous transmit and receive mode, after
checking that the SCI has finished transmission and the TDRE and TEND flags are set to 1, clear
TE to 0. Then simultaneously set TE and RE to 1 with a single instruction. To switch from receive
mode to simultaneous transmit and receive mode, after checking that the SCI has finished
reception, clear RE to 0. Then after checking that the RDRF and receive error flags (ORER, FER,
and PER) are cleared to 0, simultaneously set TE and RE to 1 with a single instruction.