CHAPTER 14 ASYNCHRONOUS SERIAL INTERFACE (UART)
User’s Manual U16896EJ2V0UD
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14.4 Interrupt Request Signals
The following three types of interrupt request signals are generated from UARTn.
•
Reception error interrupt request signal (INTSREn)
•
Reception completion interrupt request signal (INTSRn)
•
Transmission completion interrupt request signal (INTSTn)
The default priorities among these three types of interrupt request signals are, from high to low, reception error
interrupt, reception completion interrupt, and transmission completion interrupt.
Table 14-2. Generated Interrupt Request Signals and Default Priorities
Interrupt Request Signal
Priority
Reception error interrupt request signal (INTSREn)
1
Reception completion interrupt request signal (INTSRn)
2
Transmission completion interrupt request signal (INTSTn)
3
(1) Reception error interrupt request signal (INTSREn)
When reception is enabled, the INTSREn signal is generated according to the logical OR of the three types of
reception errors explained for the ASISn register. Whether the INTSREn signal or the INTSRn signal is
generated when an error occurs can be specified according to the ASIMn.ISRMn bit.
When reception is disabled, the INTSREn signal is not generated.
(2) Reception completion interrupt request signal (INTSRn)
When reception is enabled, the INTSRn signal is generated when data is shifted in to the receive shift register
and transferred to the RXBn register.
The INTSRn signal can be generated in place of the INTSREn signal according to the ISRMn bit even when a
reception error has occurred.
When reception is disabled, the INTSRn signal is not generated.
(3) Transmission completion interrupt request signal (INTSTn)
The INTSTn signal is generated when one frame of transmit data containing 7-bit or 8-bit characters is shifted
out from the transmit shift register.
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