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RL78/G1A CHAPTER 12 SERIAL ARRAY UNIT
R01UH0305EJ0200 Rev.2.00 533
Jul 04, 2013
(3) Permissible baud rate range for reception
The permissible baud rate range for reception during UART (UART0 to UART2) 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.
2 × k × Nfr
(Maximum receivable baud rate) =
2 × k × Nfr − k + 2
× Brate
2 × k × (Nfr − 1)
(Minimum receivable baud rate) =
2 × k × Nfr − k − 2
× Brate
Brate: Calculated baud rate value at the reception side (See 12.6.4 (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, 3), mn = 01, 03, 11
Figure 12-94. Permissible Baud Rate Range for Reception (1 Data Frame Length = 11 Bits)
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
As shown in Figure 12-94, 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.