DEMO9S08LC60 Freescale Semiconductor, DEMO9S08LC60 Datasheet - Page 195

• Manufacturer Part Number: DEMO9S08LC60
• Description: BOARD DEMO FOR 9S08LC60
• Manufacturer: Freescale Semiconductor
• Type: MCUr

Specifications of DEMO9S08LC60

• Contents: Evaluation Board
• Processor To Be Evaluated: MC9S08LC60
• Interface Type: RS-232, USB
• Silicon Manufacturer: Freescale
• Core Architecture: HCS08
• Core Sub-architecture: HCS08
• Silicon Core Number: MC9S08
• Silicon Family Name: S08LC
• Rohs Compliant: Yes
• For Use With/related Products: MC9S08LC60
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

10.6.5
The internally generated clock source is guaranteed to have a period ± 25% of the nominal value. In some
cases, this may be sufficient accuracy. For other applications that require a tight frequency tolerance, a
trimming procedure is provided that will allow a very accurate source. This section outlines one example
of trimming the internal oscillator. Many other possible trimming procedures are valid and can be used.
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 reduction divisor (R) twice the final value. After the trim procedure is complete, the reduction divisor
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) ICG configured for internal reference with 4 MHz bus
Example #4: Internal Clock Generator Trim
INCREASES THE FREQUENCY)
(DECREASING ICGTRM
ICGTRM - 128 / (2**n)
COUNT < EXPECTED = 500
(RUNNING TOO SLOW)
ICGTRM =
MC9S08LC60 Series Data Sheet: Technical Data, Rev. 4
n = n + 1
IS n > 8?
(COUNT = # OF BUS CLOCKS / 4)
DECREASES THE FREQUENCY)
Figure 10-17. Trim Procedure
NO
START TRIM PROCEDURE
INCOMING CLOCK WIDTH
(INCREASING ICGTRM
ICGTRM = $80, n = 1
ICGTRM + 128 / (2**n)
CASE STATEMENT
MEASURE
ICGTRM =
YES
.
COUNT > EXPECTED = 500
(RUNNING TOO FAST)
COUNT = EXPECTED = 500
Chapter 10 Internal Clock Generator (S08ICGV4)
Figure 10-17
STORE ICGTRM VALUE
IN NON-VOLATILE
CONTINUE
MEMORY
while the
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