
CHAPTER 15 ASYNCHRONOUS SERIAL INTERFACE (UART)
User
’
s Manual U15862EJ3V0UD
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15.5 Interrupt Requests
The following three types of interrupt requests are generated from UARTn.
Reception error interrupt (INTSREn)
Reception completion interrupt (INTSRn)
Transmission completion interrupt (INTSTn)
The default priorities among these three types of interrupt requests is, from high to low, reception error interrupt,
reception completion interrupt, and transmission completion interrupt.
Table 15-1. Generated Interrupts and Default Priorities
Interrupt
Priority
Reception error
1
Reception completion
2
Transmission completion
3
(1) Reception error interrupt (INTSREn)
When reception is enabled, a reception error interrupt is generated according to the logical OR of the three
types of reception errors explained for the ASISn register. Whether a reception error interrupt (INTSREn) or
a reception completion interrupt (INTSRn) is generated when an error occurs can be specified according to
the ISRMn bit of the ASIMn register.
When reception is disabled, no reception error interrupt is generated.
(2) Reception completion interrupt (INTSRn)
When reception is enabled, a reception completion interrupt is generated when data is shifted in to the
reception shift register and transferred to reception buffer register n (RXBn).
A reception completion interrupt request can be generated in place of a reception error interrupt according to
the ISRMn bit of the ASIMn register even when a reception error has occurred.
When reception is disabled, no reception completion interrupt is generated.
(3) Transmission completion interrupt (INTSTn)
A transmission completion interrupt is generated when one frame of transmit data containing 7-bit or 8-bit
characters is shifted out from the transmission shift register.