Fujitsu FR60 Hardware Manual page 433

[bit 10] Transfer status bit (BUSY)
The transfer status bit indicates whether serial transfer is being executed.
BUSY
0 Stopped, or standing by for serial data register R/W [default]
1 Serial transfer
This bit is initialized to "0" upon a reset. This is a read-only bit.
[bit 9] Stop bit (STOP)
The stop bit forcibly terminates serial transfer. If "1" is written to this bit (STOP=1), the serial transfer
enters the stop state.
STOP
0 Normal operation
1 Transfer stop by STOP=1 [default value]
This bit is initialized to "1" upon a reset. This bit is readable and writable.
[bit 8] Start bit (STRT: Start)
The start bit activates serial transfer. Writing "1" to this bit while serial transfer is in the stop state starts
serial transfer. Writing "1" to this bit is ignored and writing "0" has no effect while the device is
performing serial transfer or waiting for reading or writing of data in the serial shift register.
"0" is always read from this bit.
[Bit 3] Serial mode selection bit (MODE)
The serial mode selection bit is used to select the condition for starting transfer operation from the stop
state. This bit must not be updated during a transfer operation.
MODE
0 Transfer is started when the STRT bit is set to "1". (Default)
1 Transfer is started when data is read from or written to the serial data register.
This bit is cleared to "0" by a reset and can be read and written. Be sure to write "1" to this bit before
starting DMA.
[Bit 2] Transfer direction select bit (BDS: Bit Direction Select)
The transfer direction select bit is used to select the transfer mode for serial data I/O from LSB-first
mode (transfer begins with the least significant bit) and MSB-first mode (transfer begins with the most
significant bit), as shown below.
Value
0 LSB-first mode (default)
1 MSB-first mode
Operation
Operation
Operation
Meaning
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