Usage Example; Figure 5.1 Example Of Operational Procedure - Toshiba TXZ SERIES Reference Manual

5. Usage Example

The operation procedure of the frequency detection circuit is as follows:
When a reset is asserted, the cause of the reset should be checked in the [RLMRSTFLG1] register. If the cause
is not the frequency detection reset, the external oscillation should be enabled, the register settings should be done
to use the frequency detection circuit, and its operation should be enabled. And the reset output of OFD should be
disabled.
After the detection starts, the abnormality detection flag in the [OFDSTAT] register should be checked. If any
abnormalities are not present, the clock should be changed to the external oscillation clock.
[RLMRSTFLG1]
<OFDRSTF>=0 ?
Enable external oscillation setting
Enable write register
([OFDCR1]=0xF9)
Disable reset output
(<OFDRSTEN>=0)
target clock selection
(<OFDMON>=0)
Enable OFD operation
([OFDCR2]=0xE4)
2018-03-09
Reset
no
yes
Error operation
OFD setting
(<OFDMN0>
,<OFDMX0>)

Figure 5.1 Example of operational procedure

[OFDSTAT]
<OFDBUSY>=1 ?
[OFDSTAT]
<FRQERR>=1 ?
Disable OFD operation
([OFDCR2]=0x00)
external oscillation change
(<OSCSEL>=1)
Enable reset output
(<OFDRSTEN>=1)
Enable ＯＦＤ ｏｐｅｒａｔｉｏｎ
([OFDCR2]=0xE4)
Disable write register
([OFDCR1]=0x06)
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TXZ Family
Ocsillation Frequency Detector
no
yes
yes
no
Error operation
Rev. 1.1