RL78/F13, F14 CHAPTER 15 SERIAL ARRAY UNIT
R01UH0368EJ0210 Rev.2.10 980
Dec 10, 2015
(3) Permissible baud rate range for reception
The permissible baud rate range for reception during UART (UART0, UART1) communication can be calculated by
the following expression. Make sure that the baud rate at the transmission side is within the permissible baud rate
range at the reception side.
(Maximum receivable baud rate) =
2 × k × Nfr
× Brate
2 × k × Nfr − k + 2
(Minimum receivable baud rate) =
2 × k × (Nfr − 1)
× Brate
2 × k × Nfr − k − 2
Brate: Calculated baud rate value at the reception side (See 15.7.3 (1) Baud rate calculation expression.)
k: SDRmn[15:9] + 1
Nfr: 1 data frame length [bits]
= (Start bit) + (Data length) + (Parity bit) + (Stop bit)
Remark m: Unit number (m = 0, 1), n: Channel number (n = 1), mn = 01, 11
Figure 15-135. Permissible Baud Rate Range for Reception (1 Data Frame Length = 11 Bits)
As shown in Figure 15-135, the timing of latching receive data is determined by the division ratio set by bits 15 to 9
of serial data register mn (SDRmn) after the start bit is detected. If the last data (stop bit) is received before this latch
timing, the data can be correctly received.
FL
1 data frame (11 × FL)
(11 × FL)
min.
(11 × FL) max.
Data frame length
of SAU
Start
bit
Bit 0 Bit 1 Bit 7
Parity
bit
Permissible minimum
data frame length
Permissible maximum
data frame length
Stop
bit
Start
bit
Bit 0 Bit 1 Bit 7
Parity
bit
Latch
timing
Stop
bit
Start
bit
Bit 0 Bit 1 Bit 7
Parity
bit
Stop
bit
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