Datasheet

Section 12 Serial Communication Interface
Rev.7.00 Dec. 24, 2008 Page 411 of 698
REJ09B0074-0700
Table 12.11 SSR Status Flags and Receive Data Handling
SSR Status Flag
RDRF* ORER FER PER Receive Data Receive Error Type
1 1 0 0 Lost Overrun error
0 0 1 0 Transferred to RDR Framing error
0 0 0 1 Transferred to RDR Parity error
1 1 1 0 Lost Overrun error + framing error
1 1 0 1 Lost Overrun error + parity error
0 0 1 1 Transferred to RDR Framing error + parity error
1 1 1 1 Lost Overrun error + framing error +
parity error
Note: * The RDRF flag retains the state it had before data reception.
Yes
<End>
[1]
No
Initialization
Start reception
[2]
No
Yes
Read RDRF flag in SSR
[4]
[5]
Clear RE bit in SCR to 0
Read ORER, PER, and
FER flags in SSR
Error processing
(Continued on next page)
[3]
Read receive data in RDR, and
clear RDRF flag in SSR to 0
No
Yes
PER ∨ FER ∨ ORER = 1
RDRF = 1
All data received?
[1] SCI initialization:
The RxD pin is automatically designated as
the receive data input pin.
[2] [3] Receive error processing and break
detection:
If a receive error occurs, read the ORER,
PER, and FER flags in SSR to identify the
error. After performing the appropriate error
processing, ensure that the ORER, PER, and
FER flags are all cleared to 0. Reception
cannot be resumed if any of these flags are
set to 1. In the case of a framing error, a
break can be detected by reading the value
of the input port corresponding to the RxD
pin.
[4] SCI status check and receive data read:
Read SSR and check that RDRF = 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 end
bit for the current frame is received, reading
the RDRF flag and RDR, and clearing the
RDRF flag to 0 should be finished. The
RDRF flag is cleared automatically when
DMAC is activated by a reception complete
interrupt (RXI) and the RDR value is read.
Figure 12.12 Sample Serial Data Reception Flowchart (1)