3.
IRC Frequency Calibration
All the four main frequencies (4MHz, 8MHz, 1MHz and 455KHz) can be calibrated through
programming of the OPTION bits (CAL0, CAL1, CAL2).
When using DWTR in burning the EM78P153S under IRC mode, the DWTR will
calibrate automatically
. For example, if user chooses 4MHz base-frequency in IRC mode,
the DWTR will automatically calibrate the IRC frequency to 4MHz through the OPTION bits
(CAL0, CAL1, CAL2).
Take note that adjusting the OPTION bits will cause the internal RC frequency to drift. So,
this OPTION bits are not provided in the DWTR software after Version 4.3.
(1) DWTR Setting
When using DWTR in burning EM78P153S, the drift rate of
±
5% is guaranteed
under IRC 4M Hz, and the drift rate of
±
10% is guaranteed under IRC 1M, 8M, 455K
Hz.
Assuming that user chooses 4MHz in IRC mode, DWTR guarantees that the IRC
frequency range is from 3.8MHz to 4.2MHz. If the IRC frequency drift rate exceeds the
±
5% guaranteed frequency (after burning in IRC mode with DWTR), DWTR will sound an
alarm (a beep signal) to alert user.
Remark: Drift rate of
±
5% is guaranteed under all the four main frequencies for
DWTR4K.
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