AN2156 Freescale Semiconductor / Motorola, AN2156 Datasheet - Page 36

• Manufacturer Part Number: AN2156
• Description: Programming and Erasing FLASH and EEPROM Memories on the MC68HC908AS60A/AZ60A
• Manufacturer: Freescale Semiconductor / Motorola

Application Note
Practical Considerations for Programming/Erasing
Evaluating Delay Times for the Sample Code
36
To ensure successful programming and erasing of the FLASH and/or
EEPROM on the MC68HC908AS60A/AZ60A, the user should consider
the following suggestions:
The FLASH and EEPROM algorithms include specific wait steps. These
delay times are defined in the MC68HC908AS60A/AZ60A specification
and must be considered when utilizing the algorithms.
To ensure that each wait step meets the specification, the delay times
have to be evaluated. All delays in the sample code provided in this
application note were evaluated and confirmed to meet the specification
using a general I/O port pin. The port pin was initialized with a high
output signal. Just before entering a delay, the port pin was toggled low
and held low until the end of the delay. The actual delay times shown in
Table
oscilloscope. To toggle the port pin, instructions BSET, BCLR, and COM
were used. The sample code also includes the instructions used for the
delay time evaluation.
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Freescale Semiconductor, Inc.
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Provide a good ground.
Provide a clean and constant clock during the program and erase
operations.
Filter all signals leaving a noisy environment.
If a microcontroller is programmed or erased in a socket, ensure
that all pins are making good electrical contact.
Provide an electrically noise-free environment for the MCU. The
V
Decoupling capacitors should be placed very close to the V
pin pairs. Any high current switching activity on the PCB or in the
general vicinity should be disabled during programming.
7,
DD
Table
supply should be filtered and within the specification limits.
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8, and
Table 9
were the low periods as measured on an
MOTOROLA
DD
AN2156
/V
SS