14.3 Operation
14.3.1 Overview
The SCI supports serial data transfer in both asynchronous and synchronous modes.
The communication format depends on settings in the SMR as indicated in table 14-5. The clock
source and usage of the SCK pin depend on settings in the SMR and SCR as indicated in table 14-6.
Table 14-5 Communication Formats Used by SCI
SMR Stop Bit
C/A CHR PE STOP Mode Format Parity Length
0 0 0 0 Asynchronous 8-Bit data None 1
12
10 Yes 1
12
1 0 0 7-Bit data None 1
12
10 Yes 1
12
1 — — — Synchronous 8-Bit data — —
Table 14-6 SCI Clock Source Selection
SMR SCR Clock
C/A CKE1 CKE0 Source SCK Pin
0 0 0 Internal I/O port*
(Async 1 Clock output at same frequency as baud rate
mode) 1 0 External Clock input at 16 times the baud rate frequency
1
1 0 0 Internal Serial clock output
(Sync 1
mode) 1 0 External Serial clock input
1
* Cannot be used by the SCI.
Transmitting and receiving operations in the two modes are described next.
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