CHAPTER 11 SERIAL INTERFACE FUNCTION
User’s Manual U14359EJ4V0UM
387
(4) Allowable baud rate range during reception
The degree to which a discrepancy from the transmission destination’s baud rate is allowed during reception
is shown below.
Caution
The equations described below should be used to set the baud rate error during reception
so that it always is within the allowable error range.
Figure 11-13. Allowable Baud Rate Range During Reception
FL
1 data frame (11
×
FL)
FLmin
FLmax
UARTn
transfer rate
Latch timing
Start bit
Bit 0
Bit 1
Bit 7
Parity bit
Minimum allowable
transfer rate
Maximum allowable
transfer rate
Stop bit
Start bit
Bit 0
Bit 1
Bit 7
Parity bit
Stop bit
Start bit
Bit 0
Bit 1
Bit 7
Parity bit
Stop bit
Remark
n = 0 to 2
As shown in Figure 11-13, after the start bit is detected, the receive data latch timing is determined according
to the counter that was set by the BRGCn register. If all data up to the final data (stop bit) is in time for this
latch timing, the data can be received normally.
Applying this to 11-bit reception is, theoretically, as follows.
FL = (Brate)
−
1
Brate: UARTn baud rate (n = 0 to 2)
k:
BRGCn setting value (n = 0 to 2)
FL:
1-bit data length
Latch timing margin: 2 clocks
Minimum allowable transfer rate:
FL
k
2
2
k
21
FL
k
2
2
k
FL
11
FLmin
+
=
×
−
−
×
=
