Figure 16.22 Sample Serial Reception Flowchart - Renesas H8S/2158 User Manual

Section 16 Serial Communication Interface (SCI, IrDA, and CRC)
Read ORER flag in SSR
Read RDRF flag in SSR
No
Read receive data in RDR and
clear RDRF flag in SSR to 0
No
All data received?
Clear RE bit in SCR to 0
[3]
Overrun error processing
Clear ORER flag in SSR to 0
Rev. 3.00 Jan 25, 2006 page 442 of 872
REJ09B0286-0300
Initialization
Start reception
Yes
ORER = 1
No
Error processing
(Continued below)
RDRF = 1
Yes
Yes
<End>
Error processing
<End>

Figure 16.22 Sample Serial Reception Flowchart

[1] SCI initialization:
[1]
The RxD pin is automatically
designated as the receive data input
pin.
[2] [3] Receive error processing:
If a receive error occurs, read the
[2]
ORER flag in SSR, and after
performing the appropriate error
processing, clear the ORER flag to 0.
[3]
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
[4]
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
[5]
flag to 0 should be finished.
However, the RDRF flag is cleared
automatically when the DTC is
initiated by a receive data full interrupt
(RXI) and reads data from RDR.