Section 14 Synchronous Serial Communication Unit (SSU)
Rev. 3.00 Mar. 14, 2006 Page 541 of 804
REJ09B0104-0300
Yes
Start
[1]
[2]
[3]
[4][1] Initial setting:
Specify the transmit data format.
[2] Check that the SSU state and write transmit data:
Write transmit data to SSTDR after reading and confirming
that the TDRE bit is 1. The TDRE bit is automatically cleared
to 0 and transmission is started by writing data to SSTDR.
[3] Procedure for consecutive data transmission:
To continue data transmission, confirm that the TDRE bit is 1
meaning that SSTDR is ready to be written to. After that, data
can be written to SSTDR. The TDRE bit is automatically
cleared to 0 by writing data to SSTDR.
[4] Procedure for data transmission end:
To end data transmission, confirm that the TEND bit is cleared
to 0. After completion of transmitting the last bit, clear the TE
bit to 0.
Note: Hatching boxes represent SSU internal operations.
Initial setting
Read TDRE in SSSR
TDRE = 1?
Yes
Yes
No
No
No
Write transmit data to SSTDR
TDRE automatically cleared
Data transferred from SSTDR to SSTRSR
Set TDRE to 1 to start transmission
Consecutive data transmission?
Read TEND in SSSR
TEND = 1?
Clear TE in SSER to 0
End transmission
Yes
No
Confirm that TEND is cleared to 0
One bit time
quantum elapsed?
Clear TEND to 0
[4]
Figure 14.14 Flowchart Example of Transmission Operation
(Clock Synchronous Communication Mode)
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