Data Transfer Operations - Hitachi HD6473867 Hardware Manual

3. Data transfer operations

• SCI3 initialization
Data transfer on SCI3 first of all requires that SCI3 be initialized as described in 10.1.4 (3)(a). SCI3
initialization, and shown in figure 10-5.
• Transmitting
Figure 10-11 shows an example of a flowchart for data transmission. This procedure should be
followed for data transmission after initializing SCI3.
Sets bits SPC31 and
SPC32 to 1 in SPCR
Read bit TDRE
1
TDRE = 1?
Write transmit
data to TDR
Continue data
2
transmission?
Read bit TEND
TEND = 1?
Clear bit TE to 0
in SCR3
Figure 10-11 Example of Data Transmission Flowchart (Synchronous Mode)
Start
in SSR
No
Yes
Yes
No
in SSR
No
Yes
End
1. Read the serial status register (SSR) and
check that bit TDRE is set to 1, then write
transmit data to the transmit data register
(TDR). When data is written to TDR, bit
TDRE is cleared to 0 automatically, the
clock is output, and data transmission is
started. When clock output is selected,
the clock is output and data transmission
started when data is written to TDR.
2. When continuing data transmission, be
sure to read TDRE = 1 to confirm that
a write can be performed before writing
data to TDR. When data is written to
TDR, bit TDRE is cleared to 0 automatically.
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