NEC UPD703116 User Manual page 439

(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 10-13. Allowable Baud Rate Range During Reception
UART0
transfer rate
Minimum allowable
transfer rate
Maximum allowable
transfer rate
As shown in Figure 10-13, after the start bit is detected, the receive data latch timing is determined according
to the counter that was set by the BRGC0 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.
–1
FL = (Brate)
Brate: UART0 baud rate
k: BRGC0 register setting value
FL: 1-bit data length
When the latch timing margin is made 2 base clocks, the minimum allowable transfer rate (FLmin) is
as follows.
= × −
FL min 11 FL
CHAPTER 10 SERIAL INTERFACE FUNCTION
Latch timing
Start bit Bit 0 Bit 1
FL
Start bit Bit 0 Bit 1
Start bit Bit 0 Bit 1
− +
k 2 21 k 2
× =
FL
2 k 2 k
User's Manual U14492EJ5V0UD
Bit 7 Parity bit
1 data frame (11 × FL)
Bit 7 Parity bit
FLmin
Bit 7
FLmax
FL
Stop bit
Stop bit
Parity bit Stop bit
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