R8A66171SP RENESAS [Renesas Technology Corp], R8A66171SP Datasheet - Page 7

• Manufacturer Part Number: R8A66171SP
• Description: A2RT (ADVANCED ASYNCHRONOUS RECEIVER & TRANSMITTER)
• Manufacturer: RENESAS [Renesas Technology Corp]

R8A66171DD/SP
SUPPLEMENTARY DESCRIPTION
REJ03F269-0100 Rev.1.00 Feb.19.2008
Page 7 of 22
FIFO
● Wakeup
When CRC is enabled
When parity is enabled
Start
Start
bit
bit
The wakeup mode of the R8A66171 can be set by setting the D2 bit of command4 to “1”. In wakeup
mode, a 9
Only the 9
The wakeup is used when one master MCU and multiple local MCU are connected by serial I/O.
Examples of wakeup are shown below.
The major purpose is not to interrupt the MCU by each character. The MCU is interrupted when:
Transmit data buffer (FIFO) empty
Receive data buffer (FIFO) full or packet end
The MCU interruption interval is as follows:
Approximately 90µs (min) until the FIFO becomes full at 500kbps.
Approximately 36.7ms (min) until the FIFO becomes full at 1.2kbps.
Read/write operation by the MCU should be made for all data in FIFO at once.
Address of local MCU1
Address of local MCU1
① Initial setting
② Wakeup mode
③ Wakeup and data transfer (between master MCU and local MCU1)
8-bit
data
8-bit
data
The initial setting should be made by the input of each command.
The wakeup mode of the R8A66171 is activated by setting D2 bit of the command4 to “1”.
Command5 can be input as the second byte of command4 by setting D2 bit of the command4 to
“1” and each address is input. In the wakeup mode, the 9
remain the same.
Data is transmitted from the master MCU to each local MCU.
The first byte should hold the address of the local MCU. (in this case local MCU1.)
Each local R8A66171 checks the data (address) against command5 (each address) when the
first byte (address) is received. The R8A66171 which matches the address starts to accept the
following data (wakeup).
The R8A66171 which does not match the address, only accepts data, where the 9
The 9th
The 9th
th
bit
bit
th
Parity
bit is automatically added (the wakeup bit).
bit of the first byte is “1”, and the remainder blocks 9
bit
Stop
bit
Stop
bit
Start
bit
Start
bit
8-bit
data
Transfer block
8-bit
data
Transfer block
The 9th
bit
The 9th
Stop
bit
bit
Parity
bit
Stop
bit
Start
bit
Start
bit
8-bit
data
8-bit
data
The 9th
bit
The 9th
bit
Stop
bit
Parity
bit
Stop
Start
bit
bit
8-bit
data
th
bits are set to “0”.
th
Master
MCU
bit is automatically added. Others
The 9th
Block check character
Note : The w akeup function is automatically
bit
canceled w hen the transfer block data
has been read by the MCU.
(The w akeup mode continues.)
Stop
R8A66171
R8A66171
R8A66171
bit
Start
bit
1 to 1
8-bit
data
R8A66171
R8A66171
R8A66171
The 9th
th
bit
bit is “1”.
Local
MCU 1
Local
MCU 2
Local
MCU 3
Stop
bit