CHAPTER 14 SERIAL INTERFACE CHANNEL 1
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User’s Manual U11302EJ4V0UM
(a) When automatic transmit/receive function is performed using an internal clock
The internal clock operation is selected when bit 1 (CSIM11) of serial operating mode register 1
(CSIM1) is set to 1.
In this case, the interval is determined as follows by CPU processing.
When bit 7 (ADTI7) of the automatic data transmit/receive interval specification register (ADTI) is set
to 0, the interval is determined by CPU processing. When ADTI7 is set to 1, the interval is determined
by the contents of ADTI or by CPU processing, whichever is greater.
For the interval determined by ADTI, see
Figure 14-5 Format of Automatic Data Transmit/Receive
Interval Specification Register
.
Table 14-3. Interval Determined by CPU Processing (with Internal Clock Operation)
CPU Processing
Interval
When using multiplication instruction
MAX. (2.5T
SCK
, 13T
CPU
)
When using division instruction
MAX. (2.5T
SCK
, 20T
CPU
)
External access 1-wait mode
MAX. (2.5T
SCK
, 9T
CPU
)
Other than above
MAX. (2.5T
SCK
, 7T
CPU
)
T
SCK
:
1/f
SCK
f
SCK
:
Serial clock frequency
T
CPU
:
1/f
CPU
f
CPU
:
CPU clock (set by bits 0 to 2 (PCC0 to PCC2) of the
processor clock control register (PCC))
MAX. (a, b) : a or b, whichever is greater
Figure 14-24. Operation Timing When Automatic Transmit/Receive
Function Is Operating with Internal Clock
f
X
:
Main system clock oscillation frequency
f
CPU
: CPU clock (set by bits 0 to 2 (PCC0 to PCC2) of the processor clock control register (PCC))
T
CPU
: 1/f
CPU
T
SCK
: 1/f
SCK
f
SCK
:
Serial clock frequency
f
X
f
CPU
(n = 1)
SCK1
SO1
SI1
T
CPU
T
SCK
Interval
D7
D6
D5
D4
D3
D2
D1
D0
D7
D6
D5
D4
D3
D2
D1
D0