MC9S08AW32CFGE Freescale, MC9S08AW32CFGE Datasheet - Page 155

• Manufacturer Part Number: MC9S08AW32CFGE
• Manufacturer: Freescale

Specifications of MC9S08AW32CFGE

• Cpu Family: HCS08
• Device Core Size: 8b
• Frequency (max): 40MHz
• Interface Type: I2C/SCI/SPI
• Total Internal Ram Size: 2KB
• # I/os (max): 34
• Number Of Timers - General Purpose: 8
• Operating Supply Voltage (typ): 3.3/5V
• Operating Supply Voltage (max): 5.5V
• Operating Supply Voltage (min): 2.7V
• On-chip Adc: 8-chx10-bit
• Instruction Set Architecture: CISC
• Operating Temp Range: -40C to 85C
• Operating Temperature Classification: Industrial
• Mounting: Surface Mount
• Pin Count: 44
• Package Type: LQFP
• Program Memory Type: Flash
• Program Memory Size: 32KB
• Lead Free Status / RoHS Status: Compliant

8.5.5
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 =
n = n + 1
IS n > 8?
(COUNT = # OF BUS CLOCKS / 4)
DECREASES THE FREQUENCY)
MC9S08AW60 Data Sheet, Rev 2
Figure 8-17. 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 8 Internal Clock Generator (S08ICGV4)
Figure 8-17
STORE ICGTRM VALUE
IN NON-VOLATILE
CONTINUE
MEMORY
while the
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