Example Of Uart Transmit Operation - Renesas M32R/ECU Series User Manual

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12.6.9 Example of UART Transmit Operation

The following shows a typical transmit operation in UART mode.
<UART on transmit side>
Transmit enable bit
Transmit buffer
empty bit
Transmit status bit
SIO transmit interrupt request (Note 1)
(When transmit buffer empty
interrupt is selected)
(When transmission finished
interrupt is selected)
Note 1: Changes of the Interrupt Controller's SIO Transmit Interrupt Control Register interrupt request bit
Note 2: When transmit buffer empty interrupt is enabled (DMA transfer can also be requested at the same time)
Note 3: When transmission finished interrupt is enable
Note 4: The Interrupt Controller's IVECT register is read or the SIO Transmit Interrupt Control Register interrupt request bit cleared
Note 5: A transmit interrupt request is generated when transmission is enabled.
Note 6: Be aware that even after transmit data is written to the transmit buffer, a transmit interrupt request is generated when the
data is transferred from the transmit buffer to the transmit shift register and the transmit buffer is thereby emptied.
Note 7: A transmission finished interrupt request is generated when data in the transmit shift register has all been transmitted.
Figure 12.6.5 Example of UART Transmission (Transmitted Only Once)
<UART on transmit side>
TXD
Set
Write to the
transmit buffer
register
TXD
Transmit
interrupt request
(Note 2)
(Note 5)
Interrupt request accepted (Note 4)
: Processing by software
12.6 Transmit Operation in UART Mode
<UART on receive side>
RXD
Set
Transferred from the transmit buffer
to the transmit shift register
(transmission starts)
ST b7 b6 b0
Transmit interrupt request
(Note 2)(Note 6)
Interrupt request accepted (Note 4)
: Interrupt request generated
12-46
Serial I/O
Cleared
Cleared
PAR
SP SP
Transmit interrupt request
(Note 3)(Note 7)
32180 Group User's Manual (Rev.1.0)