Flag Set Timings For A Receive Operation (In Mode 2) - Fujitsu MB90390 Series Hardware Manual

19.9.2

Flag Set Timings for a Receive Operation (in Mode 2)

The RDRF flag is set when the final stop bit is detected and reception transfer ends with
the last data bit (D8) having the value "1".
The ORFE flag is set when the final stop bit is detected, irrespective of the value of the
last data bit (D8). The data in UIDR is invalid when the ORFE bit is active.
The interrupt request to the CPU is generated when either of the flags are set (see
Section "19.10 UART0, UART1 Application Example" for details on using mode 2).
■ Flag Set Timings for a Receive Operation (in Mode 2)
Receive interrupt
Data
D7
RDRF = 1
ORFE
Receive interrupt
Figure 19.9-4 RDRF Set Timing (Mode 2)
Data
D6 D7
RDRF
Figure 19.9-5 ORFE Set Timing (Mode 2)
D8 Stop
(Overrun error)
D8 (Stop)
Stop
Data
D7
RDRF = 0
ORFE
Receive interrupt
CHAPTER 19 UART0, UART1
D8 Stop
(Framing error)
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