Datasheet
RL78/L12 CHAPTER 12 SERIAL ARRAY UNIT
R01UH0330EJ0200 Rev.2.00 381
Dec 13, 2013
CHAPTER 12 SERIAL ARRAY UNIT
Serial array unit has two serial channels. Each channel can achieve 3-wire serial (CSI), and UART.
Function assignment of each channel supported by the RL78/L12 is as shown below.
Channel Used as CSI Used as UART
0 CSI00 UART0 (supporting LIN-bus)
1 CSI01
12.1 Functions of Serial Array Unit
Each serial interface supported by the RL78/L12 has the following features.
12.1.1 3-wire serial I/O (CSI00, CSI01)
Data is transmitted or received in synchronization with the serial clock (SCK) output from the master channel.
3-wire serial communication is clocked communication performed by using three communication lines: one for the serial
clock (SCK), one for transmitting serial data (SO), one for receiving serial data (SI).
For details about the settings, see 12.5 Operation of 3-Wire Serial I/O (CSI00, CSI01) Communication.
[Data transmission/reception]
• Data length of 7 or 8 bits
• Phase control of transmit/receive data
• MSB/LSB first selectable
[Clock control]
• Master/slave selection
• Phase control of I/O clock
• Setting of transfer period by prescaler and internal counter of each channel
• Maximum transfer rate
During master communication (CSI00): Max. f
MCK/2
Notes 1, 2
During master communication (other than CSI00): Max. fMCK/4
Note 2
During slave communication: Max. f
MCK/6
Note 2
[Interrupt function]
• Transfer end interrupt/buffer empty interrupt
[Error detection flag]
• Overrun error
In addition, CSI00 supports the SNOOZE mode. When SCK input is detected while in the STOP mode, the SNOOZE
mode makes data reception that does not require the CPU possible.
Notes 1. In master communication (CSI00), maximum transfer rate become f
MCK/2 when the following conditions.
• 2.7 V ≤ EV
DD = VDD ≤ 5.5 V
• f
MCK ≤ 12 MHz
Other cases, maximum transfer rate become f
MCK/4.
2. Use the clocks within a range satisfying the SCK cycle time (t
KCY) characteristics (see CHAPTER 30
ELECTRICAL SPECIFICATIONS (A, G: T
A = -40 to +85°C) and CHAPTER 31 ELECTRICAL
SPECIFICATIONS (G: T
A = -40 to +105°C)).
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