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CHAPTER 20 UART2, UART3
20.8
Notes on Using UART2, UART3
Notes on using UART2, UART3 are given below.
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Notes on Using UART2, UART3
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Enabling operations
In UART2, UART3, the serial control register (SCR2/SCR3) has TXE (transmission) and RXE (reception)
operation enable bits. Both, transmission and reception operations, must be enabled before the
communication starts because they have been disabled as the default value (initial value). The operation
can also be canceled by disabling these bits.
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Communication mode setting
Set the communication mode while the system is not operating. If the mode is changed during transmission
or reception, the transmission or reception is stopped and possible data will be lost.
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Transmission interrupt enabling timing
The default (initial value) of the transmission data empty flag bit (SSR2/SSR3: TDRE) is "1" (no
transmission data and transmission data write enable state). A transmission interrupt request is generated as
soon as the transmission interrupt request is enabled (SSR2/SSR3: TIE=1). Be sure to set the TIE flag to
"1" after setting the transmission data to avoid an immediate interrupt.
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Start bit synchronization
MB90V390H/MB90F394H(A):
In asynchronous mode, start bit detection is level sensitive. This means that a start bit is detected
immediately if SCR2/SCR3:RXE bit is set to "1" while the serial data input SIN2/SIN3 is "0".
In asynchronous mode, a received start bit is memorized even when SCR2/SCR3:RXE bit is set to "0". This
causes immediate start of reception after SCR2/SCR3:RXE bit is set to "1" again. As a workaround, reset
UART2, UART3 by writing "1" to SMR2/SMR3:UPCL bit after setting SCR2/SCR3:RXE bit to "0".
MB90V390HA/MB90V390HB/MB90394HA:
In asynchronous mode, start bit detection is edge sensitive. This means that a start bit is not detected before
the next falling edge on the serial data input SIN2/SIN3 if SCR2/SCR3:RXE bit is set to "1" while SIN2/
SIN3 is "0".
In asynchronous mode, a received start bit is not memorized after SCR2/SCR3:RXE bit is set to "0". This
means that when SCR2/SCR3:RXE bit is set to "1" again, reception starts when a start bit is detected.
Содержание MB90390 Series
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Страница 17: ...xiii APPENDIX D List of Interrupt Vectors 690 INDEX 695 ...
Страница 18: ...xiv ...
Страница 132: ...104 CHAPTER 5 CLOCKS ...
Страница 152: ...124 CHAPTER 6 CLOCK MODULATOR ...
Страница 210: ...182 CHAPTER 11 TIME BASE TIMER ...
Страница 218: ...190 CHAPTER 12 WATCHDOG TIMER ...
Страница 264: ...236 CHAPTER 14 16 BIT RELOAD TIMER WITH EVENT COUNT FUNCTION ...
Страница 274: ...246 CHAPTER 15 WATCH TIMER ...
Страница 306: ...278 CHAPTER 17 DTP EXTERNAL INTERRUPTS ...
Страница 338: ...310 CHAPTER 18 8 10 BIT A D CONVERTER ...
Страница 364: ...336 CHAPTER 19 UART0 UART1 ...
Страница 398: ...370 CHAPTER 20 UART2 UART3 Figure 20 5 2 ORE Set Timing Receive data RDRF ORE ...
Страница 432: ...404 CHAPTER 20 UART2 UART3 ...
Страница 482: ...454 CHAPTER 22 SERIAL I O ...
Страница 560: ...532 CHAPTER 24 STEPPING MOTOR CONTROLLER ...
Страница 582: ...554 CHAPTER 27 ROM MIRRORING MODULE ...
Страница 632: ...604 CHAPTER 29 EXAMPLES OF SERIAL PROGRAMMING CONNECTION ...
Страница 722: ...694 APPENDIX ...
Страница 723: ...695 INDEX The index follows on the next page This is listed in alphabetic order ...
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