Usage Notes On Uart - Fujitsu MB90460 Series Hardware Manual

17.8

Usage Notes on UART

Notes on using UART are given below.
■ Notes on using UART
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Enabling operations
In UART, the control register (SCR0/SCR1) has both TXE (transmission) and RXE (reception) operation
enable bits. Both transmission and reception operations must be enabled before the transfer starts because
they have been disabled as the default value (initial value). The transfer can also be canceled by disabling
its operation as required.
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Communication mode setting
Set the communication mode while the system is not operating. If the mode is set during transmission or
reception, the transmission or reception data is not guaranteed.
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Synchronous mode
UART clock synchronous mode (operation mode 2) uses clock control (I/O extended serial) mode, in
which start and stop bits are not added to the data.
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Transmission interrupt enabling timing
The default (initial value) of the transmission data empty flag bit (SSR0/SSR1: TRE) is "1" (no
transmission data and transmission data write enable state). A transmission interrupt request is generated
as soon as the transmission interrupt requests are enabled (SSR0/SSR1: TIE = 1). Be sure to set the TIE
flag to "1" after setting the transmission data.
CHAPTER 17 UART
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