RX610 Group
20. Serial Communications Interface (SCI)
R01UH0032EJ0120 Rev.1.20
Page 644 of 1006
Feb 20, 2013
20.3.3
Clock
Either an internal clock generated by the on-chip baud rate generator or an external clock input to the SCKn pin can be
selected as the SCI's transfer clock, according to the setting of the CA bit in SMR and the CKE[1:0] bits in SCR.
When an external clock is input to the SCKn pin, the clock frequency should be 16 times the bit rate (when ABCS in
SEMR = 0) and 8 times the bit rate (when ABCS in SEMR = 1). In addition, when an external clock is specified, the base
clock of TMR0 and TMR1 can be selected by the ACS0 bit in SEMR of SCIn (n = 5, 6).
When the SCI is operated on an internal clock, the clock can be output from the SCKn pin. The frequency of the clock
output in this case is equal to the bit rate, and the phase is such that the rising edge of the clock is in the middle of the
transmit data, as shown in figure 20.6.
TxDn
SCKn
0
1 frame
D0
1
1
D1
D2
D3
D4
D5
D6
D7
0/1
Figure 20.6 Phase Relationship between Output Clock and Transmit Data (Asynchronous Mode)
Summary of Contents for RX600 Series
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