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08/11/04 06:21
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#75723 - PSEN and ISP
Hi all,
I'm using the Atmel 89C51RD2 micro where I can reprogram it through ISP interface. My question is if I don't need to program the micro is it OK to leave the PSEN pin not connected?
According to data sheet, at reset stage the micro reads this pin, so at reset it's an input, and if it don't have a pull up/down resistor, the micro can read any unexpected value.
Someone will say "so connect pull up/down resistor", but also according to data sheet a pull-down resistor on PSEN pin will cause the micro to enter BOOT mode and a pull-up resistor will cause the micro to enter ONCE mode.
Any ideas?

Thanks a lot,
Roberto

List of 4 messages in thread
TopicAuthorDate
PSEN and ISP            01/01/70 00:00      
   RE: PSEN and ISP            01/01/70 00:00      
   RE: PSEN and ISP            01/01/70 00:00      
   RE: PSEN and ISP            01/01/70 00:00      

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