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

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12.3.8 Example of CSIO Transmit Operation

The following shows a typical transmit operation in CSIO mode.
<CSIO on transmit side>
Transmit clock
(SCLKO)
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 8)
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 by a falling edge of the internal transfer clock pulse
at which transmission of the transmit shift register data has finished or when the transmit enable bit is cleared.
Note 8: It is inhibited to select the transmission finished interrupt when an external clock is selected.
Figure 12.3.3 Example of CSIO Transmission (Transmitted Only Once)
<CSIO on transmit side>
SCLKO
TXD
Internal clock selected
Set
Write to the
transmit buffer
register
Set by a write to the
transmit buffer
TXD
Transmit interrupt request
(Note 2) (Note 5)
Interrupt request accepted (Note 4)
: Processing by software
12.3 Transmit Operation in CSIO Mode
<CSIO on receive side>
SCLKI
RXD
External clock selected
Content of the transmit buffer register
is transferred to the transmit shift register
b7 b6 b5 b4 b3 b2
Transmit interrupt request
(Note 2) (Note 6)
: Interrupt request generated
12-30
Serial I/O
(Internal transfer clock)
Cleared
Cleared by completion
of transmission
b1 b0
Transmit interrupt request
(Note 3) (Note 7)
Interrupt request accepted
32180 Group User's Manual (Rev.1.0)