mc9s08dz32amlfr Freescale Semiconductor, Inc, mc9s08dz32amlfr Datasheet - Page 197

• Manufacturer Part Number: mc9s08dz32amlfr
• Description: Hcs08 Microcontrollers
• Manufacturer: Freescale Semiconductor, Inc

In this particular case, the MCU has been attached to a PCB and the entire assembly is undergoing final
test with automated test equipment. A separate signal or message is provided to the MCU operating under
user provided software control. The MCU initiates a trim procedure as outlined in
tester supplies a precision reference signal.
If the intended bus frequency is near the maximum allowed for the device, it is recommended to trim using
a reference divider value (RDIV setting) of twice the final value. After the trim procedure is complete, the
reference divider can be restored. This will prevent accidental overshoot of the maximum clock frequency.
Freescale Semiconductor
Initial conditions:
1) Clock supplied from ATE has 500 μsec duty period
2) MCG configured for internal reference with 8MHz bus
INCREASES THE FREQUENCY)
(DECREASING TRMVAL
TRMVAL - 256/ (2**n)
COUNT < EXPECTED = 500
(RUNNING TOO SLOW)
TRMVAL =
n = n + 1
MC9S08DZ128 Series Data Sheet, Rev. 1
IS n > 9?
(COUNT = # OF BUS CLOCKS / 8)
DECREASES THE FREQUENCY)
NO
Figure 8-13. Trim Procedure
START TRIM PROCEDURE
INCOMING CLOCK WIDTH
(INCREASING TRMVAL
TRMVAL + 256/ (2**n)
TRMVAL = $100
CASE STATEMENT
TRMVAL =
MEASURE
YES
n=1
.
COUNT > EXPECTED = 500
(RUNNING TOO FAST)
COUNT = EXPECTED = 500
Chapter 8 Multi-Purpose Clock Generator (S08MCGV2)
Figure 8-13
NON-VOLATILE MEMORY
STORE MCGTRM AND
FTRIM VALUES IN
CONTINUE
while the
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