CHAPTER 10 SERIAL INTERFACE FUNCTION
User’s Manual U15195EJ5V0UD
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10.3.4 Interrupt requests
The following two types of interrupt request are generated from UART1.
•
Reception completion interrupt (INTSR1)
•
Transmission completion interrupt (INTST1)
The reception completion interrupt has higher default priority than the transmission completion interrupt.
Table 10-5. Default Priority of Generated Interrupts
Interrupt Priority
Reception completion
1
Transmission completion
2
(1) Reception completion interrupt (INTSR1)
In the reception enabled state, the reception completion interrupt (INTSR1) is generated when data in the
receive shift register undergoes shift-in processing and is transferred to the reception buffer.
The reception completion interrupt request (INTSR1) is generated following stop-bit sampling and upon the
occurrence of an error.
In the reception disabled state, no reception completion interrupt is generated.
Caution A reception completion interrupt (INTSR1) is generated when the last bit of receive data
(stop bit) is sampled.
(2) Transmission completion interrupt (INTST1)
Since UART1 does not have a transmit buffer, a transmission completion interrupt request (INTST1) is
generated when one frame of data containing 7-bit or 8-bit characters or two frames of data containing 9-bit
characters are shifted out from the transmit shift register (TXS1, TXSL1).