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How long does it take to set the interrupt request bit to "1"?

Latest Updated:12/07/2004

Question:

(Serial Interface)  How long does it take to set the interrupt request bit to "1" after setting data to the transmit buffer in clock synchronous/UART shared serial I/O? [2004/12/07]

Answer:

When transmit shift is not being performed (TSC = 1), after writing to the transmit buffer register, 0.5 to 1.5 clocks of the shift clock are required until the interrupt request bit is set to "1". When transmit shift is being performed (TSC = 0), after writing to the transmit buffer register, transmit shift ends.
The interrupt request bit is set to "1" at the fall of the start bit of the continuously output transmit data. The shortest time possible in which the interrupt request bit can be set to "1" is when data is written to the transmit buffer immediately before setting TSC = 1 from TSC = 0. This time is 0.5 clocks of the shift clock. (#104917)
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