NEC V850ES/F 3-L Series User Manual page 424

Chapter 15
(7)
Caution
UARTn
transfer rate
Minimum
allowable
transfer rate
Maximum
allowable
transfer rate
Figure 15-12
424
Allowable baud rate range during reception
The baud rate error range at the destination that is allowable during reception
is shown below.
The baud rate error during reception must be set within the allowable error
range using the following equation.
Latch timing
Start bit Bit 0
FL
Bit 0 Bit 1
Start bit
Bit 0
Start bit
Allowable baud rate range during reception
As shown in Figure 15-12, the receive data latch timing is determined by the
counter set using the UDnCTL2 register following start bit detection. The
transmit data can be normally received if up to the last data (stop bit) can be
received in time for this latch timing.
When this is applied to 11-bit reception, the following is the theoretical result.
-1
FL = (Brate)
Brate:UARTDn baud rate
k: Setting value of UDnCTL2.UDnBRS[7:0]
FL: 1-bit data length
Latch timing margin: 2 clocks
Minimum allowable transfer rate:
×
FL min = 11 FL –
Therefore, the maximum baud rate that can be received by the destination is
as follows.
( ⁄
BRmax FLmin 11
=
User's Manual U18743EE1V2UM00
Asynchronous Serial Interface (UARTD)
Bit 1 Bit 7
1 data frame (11 × FL)
Bit 7
FLmin
Bit 1 Bit 7
FLmax
21k 2
k 2 – +
× ×
----------- - -------------------
FL = FL
2k 2k
22k
– 1
) ×
------------------- Brate
=
21k 2
+
Parity bit Stop bit
Stop bit
Parity bit
Parity bit Stop bit