12
12-30
Serial I/O
12.3 Transmit Operation in CSIO Mode
32180 Group User's Manual (Rev.1.0)
12.3.8 Example of CSIO Transmit Operation
The following shows a typical transmit operation in CSIO mode.
Figure 12.3.3 Example of CSIO Transmission (Transmitted Only Once)
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.
Internal clock selected
External clock selected
Set
Transmit enable bit
Transmit buffer empty bit
Transmit status bit
TXD
(When transmit buffer empty
interrupt is selected)
Transmit interrupt request
(Note 2) (Note 5)
Transmit interrupt request
(Note 2) (Note 6)
Interrupt request accepted (Note 4)
Set by a write to the
transmit buffer
Write to the
transmit buffer
register
Transmit clock
(SCLKO)
<CSIO on transmit side>
Cleared
Cleared by completion
of transmission
b7 b6 b5 b4 b3 b2 b1 b0
Content of the transmit buffer register
is transferred to the transmit shift register
: Interrupt request generated : Processing by software
<CSIO on transmit side>
<CSIO on receive side>
SCLKO
TXD
SCLKI
RXD
Transmit interrupt request
(Note 3) (Note 7)
Interrupt request accepted
(When transmission finished
interrupt is selected)(Note 8)
(Internal transfer clock)
SIO transmit interrupt request
(Note 1)
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