m8535 reset problem

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Hi

I have m8535 programmed to display some text in lcd..

When powerd up most of the time lcd is blank.

some times works fine (displays text as programmed)

I have nothing connected to m8535 other than lcd.

I haved checked lcd routines several times and found nothing wrong with it. ( the timing is more than what needed which was checked with 8051)

" when powered up and display goes blank, i tried giving and external reset and it started working (displaying text). So i suspect there is a reset problem. i below give fuse setting.

* BOD level set to 0.
* BOD enabled.
* internal 1Mhz clock selected
* watchdog timer disabled

Help me to solve this problem

Thanks
Nandhu

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If you are doing the LCD initialize immediately when the '8535 starts up, the LCD may not be fully powered up and be ready for the init sequence.

After AVR startup, delay for as many milliseconds as the application can tolerate before working with periperal devices. Several hundred milliseconds usually works well.

There are alternatives, such as checking the results of certain LCD operations. If it fails, re-init.

Lee

You can put lipstick on a pig, but it is still a pig.

I've never met a pig I didn't like, as long as you have some salt and pepper.

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Thanks Lee

I tried with a delay of 300ms before initilising lcd..

Here are my some doubts...

How much sould be the pull up for reset (now i am using 4k7 resistor as detailed in datasheet)

Is there any parallel port (high voltage) programmer circuit for m8535?

Thanks all

Nandhu

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Quote:

Is there any parallel port (high voltage) programmer circuit for m8535?

Short answer: Use an STK500.

Somewhat longer answer: All the information is in the datasheet, and you can use the STK500 schematic as a reference.

Lee

You can put lipstick on a pig, but it is still a pig.

I've never met a pig I didn't like, as long as you have some salt and pepper.

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I'd wait at least 500ms for the display to initialize.
A 4.7K pullup is fine.