CHAPTER 14 ASYNCHRONOUS SERIAL INTERFACE (UART)
User’s Manual U16896EJ2V0UD
429
14.6.4 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 14-17. 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
As shown in Figure 14-17, 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.
If this is applied to 11-bit reception, the following is theoretically true.
FL = (Brate)
–1
Brate: UARTn baud rate
k:
BRGCn register set value
FL:
1-bit data length
When the latch timing margin is 2 base clocks, the minimum allowable transfer rate (FLmin) is as
follows.
FL
k
2
2
k
21
FL
k
2
2
k
FL
11
min
FL
+
=
×
−
−
×
=
Содержание ?PD703302
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