
III PERIPHERAL BLOCK: SERIAL INTERFACE
S1C33L01 FUNCTION PART
EPSON
B-III-8-35
A receive-error interrupt factor occurs when a parity, framing, or overrun error is detected during reception of data.
At this time, if the following conditions are met, an interrupt to the CPU is generated:
1. The corresponding interrupt enable register bit is set to "1".
2. No other interrupt request of a higher priority has been generated.
3. The PSR's IE bit is set to "1" (interrupts enabled).
4. The set value of the corresponding interrupt priority register is higher than the CPU interrupt level (IL).
When using the receive-buffer full or transmit-buffer empty interrupt factor as an IDMA request, the fact that the
above conditions are met does not necessarily mean that an interrupt request to the CPU has been output
simultaneously when an interrupt factor occurs. An interrupt is generated under the above conditions upon
completion of the data transfer by IDMA, provided that interrupts are enabled by settings on the IDMA side.
The interrupt factor flag is set to "1" whenever an interrupt factor occurs, regardless of the settings of the interrupt-
enable and interrupt priority registers.
If the next interrupt is to be accepted following the occurrence of an interrupt, it is necessary that the interrupt factor
flag be reset, and that the PSR be set up again (by setting the IE bit to "1" after setting the IL to a value lower than the
level indicated by the interrupt priority register, or by executing the reti instruction).
The interrupt factor flag can only be reset by writing to it in the software. Note that if the PSR is set up again to
accept interrupts generated (or if the reti instruction is executed) without resetting the interrupt factor flag, the same
interrupt occurs again. Note also that the value to be written to reset the flag is "1" when the reset-only method
(RSTONLY = "1") is used, and "0" when the read/write method (RSTONLY = "0") is used.
At initial reset, all of these flags become indeterminate, so be sure to reset them in the software.
RSRX0, RSTX0: Ch.0 IDMA request (D6, D7) /
16-bit timer 5, 8-bit timer, serial I/F Ch.0 IDMA request register (0x40292)
RSRX1, RSTX1: Ch.1 IDMA request (D0, D1) / Serial I/F Ch.1, A/D IDMA request register (0x40293)
Specifies whether to invoke IDMA when an interrupt factor occurs.
When using the set-only method (default)
Write "1": IDMA request
Write "0": Not changed
Read: Valid
When using the read/write method
Write "1": IDMA request
Write "0": Interrupt request
Read: Valid
The RSRXx and RSTXx bits are IDMA request bits corresponding to receive-buffer full and transmit-buffer empty
interrupt factors, respectively. If the bit is set to "1", IDMA is invoked when an interrupt factor occurs, thus
performing a programmed data transfer. If this bit is set to "0", normal interrupt processing is performed, without
invoking IDMA.
For details on IDMA, refer to "IDMA (Intelligent DMA)".
At initial reset, these bits are set to "0" (interrupt request).