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Chapter 32 USART (LIN / FIFO)
1.Overview
■ USART operation modes
The USART operates in four different modes, which are determined by the MD0- and the MD1-bit of the Serial
mode register (SMR04). Mode 0 and 2 are used for bidirectional serial communication, mode 1 for master/
slave communication and mode 3 for LIN master/slave communication.
* means the data bit transfer format: LSB or MSB first.
** "+1" means the indicator bit of the address/data selection in the multiprocessor mode, instead of parity.
Mode 1 operation is supported both for master or slave operation of USART in a master-slave connection
system. In Mode 3 the USART function is locked to 8N1-Format, LSB first.
If the mode is changed, USART cuts off all possible transmission or reception and then awaits new action.
The MD1 and MD0 bits of the Serial Mode Register (SMR04) determine the operation mode of USART04 as
shown in the following table:
Master-slave communication
function
(multiprocessor mode)
One-to-n communication (one master to n slaves)
(This function is supported both for master and slave
system).
Synchronous mode Function as Master- or Slave-USART
Transceiving pins Direct access possible
LIN bus options - Operation as master device
- Operation as slave device
- Generation of LIN-Sync-break
- Detection of LIN-Sync-break
- Detection of start/stop edges in LIN-Sync-field
connected to ICU 0 and 2
Synchronous serial clock The synchronous serial clock can be output
continuously on the SCK pin for synchronous
communication with start & stop bits
Clock delay option Special synchronous Clock Mode for delaying clock
(useful for SPI-compliance)
16 word deep FIFO FIFO can be activated with receive progammable
trigger level
Table 1-2 USART operation modes
Operation
mode
Data length Synchroniza-
tion of mode
Length
of
stop bit
data bit
directio
n*
parity
disabled
parity
enabled
0 normal mode 7 or 8 asynchronous 1 or 2 L/M
1 multiprocessor 7 or 8 + 1** - asynchronous 1 or 2 L/M
2 normal mode 8 synchronous 0, 1 or 2 L/M
3 LIN mode 8 - asynchronous 1 L
Table 1-1 USART functions (continued)