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Renesas Electronics America - Knowledgebase

(E1, E21)Is level of difference between actual and nominal baud rates a problem?

Latest Updated:12/01/2011


Since the baud rate is determined by division of the internal clock, the actual baud rate varies slightly from the nominal value of the baud rate.
For example, when inputting a 16MHz or 32MHz clock, there is a difference of 0.16%. (Nominal value: 9600bps; Actual value: 9615bps)
Is this level of difference between the actual and nominal baud rates a problem?


In normal cases, this variation should not be a problem.
For normal UART, the margin is approximately 45% of the bit length.
When this is divided by the total bit length, the figure is a little under 4%, and even if the transmitting side and the receiving side consume half of this figure,
it is a little under 2%. Thus 0.16% is not at all a problem.
Suitable Products
RL78 Family
78K Family