Renesas M32R/ECU Series User Manual page 499

12
(3) Selecting the source of an interrupt request
The interrupt request signals sent from each SIO to the Interrupt Controller (ICU) are broadly classified into
transmit interrupts and receive interrupts. Transmit interrupt requests can be generated when the transmit
buffer is empty or transmission is finished, and the receive interrupt requests can be generated when recep-
tion is finished or an receive error is detected, as selected by the Interrupt Source Select Registers
(SI03SEL, SI45SEL).
Notes: • No interrupt request signals are generated unless interrupts are generated by the SIO Interrupt
Request Enable Register after enabling the TEN (Transmit Enable) bit or REN (Receive Enable) bit
for the corresponding SIO.
• SIO2 and SIO3 together comprise one interrupt group, so do SIO4 and SIO5.
• The transmission-finished interrupt is effective when the internal clock is selected in UART or CSIO mode.
(4) Notes on using transmit interrupts
While the SIO Interrupt Request Enable Register is set to enable interrupts, a transmit interrupt request is
generated upon enabling the corresponding TEN (Transmit Enable) bit.
(5) About DMA transfer requests from SIO
Each SIO can generate a transmit DMA transfer and a reception-finished DMA transfer request. These DMA
transfer requests can be generated by enabling each SIO's corresponding TEN (Transmit Enable) bit or REN
(Receive Enable) bit. When using DMA transfers to communicate with external devices, be sure to set the
DMA Controller (DMAC) before enabling the TEN or REN bit. No reception-finished DMA transfer requests
are generated if a receive error occurs.
• Transmit DMA transfer request
Generated when the transmit buffer is empty and the TEN bit is enabled.
TEN
(Transmit Enable bit)
TBE
(Transmit Buffer
Empty bit)
Transmit DMA
transfer request
Figure 12.2.3 Transmit DMA Transfer Request
• Reception-finished DMA transfer request
A DMA transfer request is generated when the receive buffer is filled.
RFIN
(Reception Finished bit)
Receive
DMA transfer request
Figure 12.2.4 Reception-finished DMA Transfer Request
Note: • No reception-finished DMA transfer requests are generated if a receive error occurs.
12.2 Serial I/O Related Registers
12-8
Serial I/O
32180 Group User's Manual (Rev.1.0)