Renesas rl78 User Manual

 

RL78/G1A 

 

CHAPTER  12   SERIAL  ARRAY  UNIT 

R01UH0305EJ0200  Rev.2.00 

 

 

533  

Jul 04, 2013 

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 

 

 

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.