260
CHAPTER 10 UART
10.9 UART Interrupt Occurrence and Flag Setting Timing
The UART has five flags and two interrupt causes.
The five flags are PE, ORE, FRE, RDRF, and TDRE.
One of the two interrupt causes is for data reception and the other is for data
transmission.
■
Interrupt Occurrence and Flags
PE indicates a parity error, ORE indicates an overrun, and FRE indicates a framing error. Each
flag is set when the corresponding error occurs while data is received and is cleared when "0" is
written to REC of the SCR register.
RDRF is set when received data is loaded to the SIDR register and is cleared when the data is
read from the SIDR register. Mode 1 does not support the parity check function, and mode 2
does not support the parity check and framing error detection functions.
TDRE is set when the SODR register is emptied and ready to accept the next instance of write
data and is cleared when the next data item is written to the SODR register.
In data receptuion mode, PE, ORE, FRE, or RDRF is used to request an interrupt.
In data transmission, TDRE is used to request an interrupt.
■
Interrupt Flag Set Timing for Data Reception in Mode 0
When the last stop bit is detected after data reception/transfer is completed, the PE, ORE, FRE,
and RDRF flags are set to issue an interrupt request to the CPU. If PE, ORE, or FRE is active,
the SIDR data is invalid.
Figure 10.9-1 ORE, FRE, and RDRF Set Timing (Mode 0)
D6
D7
Stop
PE, ORE, FRE
RDRF
Data
Reception interrupt
Summary of Contents for MB91F109
Page 2: ......
Page 3: ...FUJITSU LIMITED FR30 32 Bit Microcontroller MB91F109 Hardware Manual ...
Page 4: ......
Page 10: ...vi ...
Page 24: ...xx ...
Page 96: ...72 CHAPTER 2 CPU ...
Page 224: ...200 CHAPTER 4 BUS INTERFACE ...
Page 234: ...210 CHAPTER 5 I O PORTS ...
Page 268: ...244 CHAPTER 9 U TIMER ...
Page 290: ...266 CHAPTER 10 UART ...
Page 314: ...290 CHAPTER 12 16 BIT RELOAD TIMER ...
Page 322: ...298 CHAPTER 13 BIT SEARCH MODULE ...
Page 392: ...368 CHAPTER 16 FLASH MEMORY ...
Page 432: ...408 APPENDIX E Instructions F Table E 2 Instruction Formats OP rel11 5 11 ...
Page 448: ...424 APPENDIX E Instructions ...
Page 449: ...425 INDEX INDEX The index follows on the next page This is listed in alphabetic order ...
Page 458: ...434 INDEX ...
Page 460: ......
Page 461: ...FUJITSU SEMICONDUCTOR FR30 32 Bit Microcontroller MB91F109 Hardware Manual ...