Hi Dennis

Yes, you are right!
I'm using the 18F452, and I have to consistently lower RB5/PGM to get it to
start programming.
Thought they would have sorted that by now!

When I got your last mail and did the test, I tested RB4 without checking
the data sheet to see that on the 18F452 it's RB5 that's the prog pin.

Regards
Roland



At 05:51 PM 08/03/2005 -0500, you wrote:
>Hey, Roland!!
>
>I don't doubt what you're saying - I'm only giving you what I've 
>personally experienced. My programmer IS a high-voltage programmer and I 
>DID need to bring RB4 low to make my programmer handle the '628 chips. 
>It is also discussed in the errata sheet (DS80073F) on Page 9, note 3, 
>under "workaround". This is consistent with my experience. Granted, it 
>MAY not apply to your case - it definitely did apply to me!
>
>Here's the link to the errata I referenced:
>http://ww1.microchip.com/downloads/en/DeviceDoc/80073f.pdf
>
>Good luck in resolving your problem, Roland!
>Dennis
>
>Roland wrote:
>
>>At 09:10 AM 08/03/2005 -0500, you wrote:
>>  
>>
>>>Hey, Roland!
>>>
>>>You MAY find the problem with pin 10 (RB4/PGM) of the '628. Although I'm 
>>>not familiar with the AN589 programmer, I hit the same problem with my 
>>>old programmer, where I could program 'F84 chips all day long and failed 
>>>to program 'F628 chips. Turned out you need to pull pin 10 low before 
>>>you program an 'F628 chip. I just inserted a resistor from pin 10 to GND 
>>>and my problems went away. Now I can reliably program the '628s all day 
>>>long.
>>>
>>>    
>>>
>>
>>Hi Dennis
>>
>>RB4 is applicable to low voltage programming only. The AN589 cct uses high
>>voltage programming.
>>
>>As it says on most of the data sheets;
>>
>>"
>>Note 1: The High Voltage Programming mode is
>>always available, regardless of the state
>>of the LVP bit, by applying VIHH to the
>>MCLR pin.
>>"
>>
>>I've just tested it on my jig, and it programs fine in both states of RB4.
>>A problem that does crop up however, is like one of my cct's where RB6 and
>>RB7 are part of a keyboard scanning routine. The programmer(software)
>>battles to initiate the sequence, and I'd have to depress a key to halt the
>>scanning and allow programming to start.
>>
>>
>>Regards
>>Roland Jollivet
>>
>>  
>>
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Regards
Roland Jollivet

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