CHAPTER 14 ASYNCHRONOUS SERIAL INTERFACE (UART)
User’s Manual U16896EJ2V0UD
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Therefore, the transfer destination’s maximum receivable baud rate (BRmax) is as follows.
BRmax = (FLmin/11)
−
1
= Brate
Similarly, the maximum allowable transfer rate (FLmax) can be obtained as follows.
FL
k
2
2
k
21
FL
k
2
2
k
FL
11
max
FL
11
10
×
−
=
×
×
+
−
×
=
×
11
FL
k
20
2
k
21
max
FL
×
−
=
Therefore, the transfer destination’s minimum receivable baud rate (BRmin) is as follows.
BRmin = (FLmax/11)
−
1
= Brate
The allowable baud rate error of UARTn and the transfer destination can be obtained as follows from the
expressions described above for computing the minimum and maximum baud rate values.
Table 14-5. Maximum and Minimum Allowable Baud Rate Error
Division Ratio (k)
Maximum Allowable Baud Rate Error
Minimum Allowable Baud Rate Error
8 +3.53%
–3.61%
20 +4.26% –4.31%
50 +4.56% –4.58%
100 +4.66% –4.67%
255 +4.72% –4.73%
Remarks 1.
The reception precision depends on the number of bits in one frame, the base clock frequency,
and the division ratio (k). The higher the base clock frequency and the larger the division ratio
(k), the higher the precision.
2.
k: BRGCn register set value
22k
21k + 2
20k
21k
−
2
