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Table 10.12 SMR and SCR3 Settings and Clock Source Selection
SMR
SCR3
Transmit/Receive Clock
Bit 7:
COM
Bit 1:
CKE1
Bit 0:
CKE0
Mode
Clock
Source
Pin SCK
3
Function
0
0
0
Asynchronous
Internal
I/O port (SCK
3
pin not used)
1
mode
Outputs clock with same frequency as
bit rate
1
0
External
Clock should be input with frequency
16 times the desired bit rate
1
0
0
Synchronous
Internal
Outputs a serial clock
1
0
mode
External
Inputs a serial clock
0
1
1
Reserved (illegal settings)
1
0
1
1
1
1