13 UART (UART3)
13-10
Seiko Epson Corporation
S1C31D50/D51 TECHNICAL MANUAL
(Rev. 2.00)
13.7 Interrupts
The UART3 has a function to generate the interrupts shown in Table 13.7.1.
Table 13.7.1 UART3 Interrupt Function
Interrupt
Interrupt flag
Set condition
Clear condition
End of transmission
UART3_nINTF.TENDIF When the UART3_nINTF.TBEIF bit = 1
after the stop bit has been sent
Writing 1 or software reset
Framing error
UART3_nINTF.FEIF
Refer to the “Receive Errors.”
Writing 1, reading received
data that encountered an
error, or software reset
Parity error
UART3_nINTF.PEIF
Refer to the “Receive Errors.”
Writing 1, reading received
data that encountered an
error, or software reset
Overrun error
UART3_nINTF.OEIF
Refer to the “Receive Errors.”
Writing 1 or software reset
Receive buffer two
bytes full
UART3_nINTF.RB2FIF When the second received data byte is
loaded to the receive data buffer in which
the first byte is already received
Reading received data or
software reset
Receive buffer
one byte full
UART3_nINTF.RB1FIF When the first received data byte is load-
ed to the emptied receive data buffer
Reading data to empty
the receive data buffer or
software reset
Transmit buffer empty UART3_nINTF.TBEIF When transmit data written to the trans-
mit data buffer is transferred to the shift
register
Writing transmit data
The UART3 provides interrupt enable bits corresponding to each interrupt flag. An interrupt request is sent to the
CPU core only when the interrupt flag, of which interrupt has been enabled by the interrupt enable bit, is set. For
more information on interrupt control, refer to the “Interrupt” chapter.
13.8 DMA Transfer Requests
The UART3 has a function to generate DMA transfer requests from the causes shown in Table 13.8.1.
Table 13.8.1 DMA Transfer Request Causes of UART3
Cause to request DMA
transfer
DMA transfer request flag
Set condition
Clear condition
Receive buffer
one byte full
Receive buffer one byte full flag
(UART3_nINTF.RB1FIF)
When the first received data
byte is loaded to the emptied
receive data buffer
Reading data to empty
the receive data buffer or
software reset
Transmit buffer empty Transmit buffer empty flag
(UART3_nINTF.TBEIF)
When transmit data written
to the transmit data buffer is
transferred to the shift register
Writing transmit data
The UART3 provides DMA transfer request enable bits corresponding to each DMA transfer request flag shown
above for the number of DMA channels. A DMA transfer request is sent to the pertinent channel of the DMA con-
troller only when the DMA transfer request flag, of which DMA transfer has been enabled by the DMA transfer
request enable bit, is set. The DMA transfer request flag also serves as an interrupt flag, therefore, both the DMA
transfer request and the interrupt cannot be enabled at the same time. After a DMA transfer has completed, disable
the DMA transfer to prevent unintended DMA transfer requests from being issued. For more information on the
DMA control, refer to the “DMA Controller” chapter.