Operation In Synchronous Mode (Operation Mode 2) - Fujitsu MB90460 Series Hardware Manual

CHAPTER 17 UART
17.7.2

Operation in Synchronous Mode (Operation Mode 2)

The clock synchronous transfer method is used for UART operation mode 2 (normal
mode).
■ Operation in Synchronous Mode (Operation Mode 2)
●
Transfer data format
In synchronous mode, 8-bit data is transferred using the LSB first method, in which start and stop bits are
not added. Figure 17.7-3 shows the data format in clock synchronous mode.
Transmission data writing
Transmitting and reception
clock
RXE, TXE
Transmission and reception
data
●
Clock supply
In clock synchronous mode (I/O extended serial), as many clocks as the number of transmission and
reception bits must be supplied.
• When the internal clock (dedicated baud rate generator or internal timer) is selected, the data receiving
synchronous clocks is generated automatically if data is transmitted.
• When the external clock is selected, confirm that the transmission side UART output data register
(SODR0/SODR1) contains data (SSR0/SSR1: TDRE = 0). Then, clocks for just 1 byte must be
supplied from outside.
The mark level (H) must be retained before transmission starts and after it is complete.
●
Error detection
Only overrun errors can be detected; parity and framing errors cannot be detected.
502
Figure 17.7-3 Transfer Data Format (Operation Mode 2)
LSB
01001101
B
1 0 1 1 0 0
is transferred.
Mark level
1 0
(Mode 2)
MSB