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Will Reeve
Joined: 30 Oct 2003
Posts: 209
Location: Norfolk, England
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| 18LF452 being reported as 18F452 |
 Posted: Wed Mar 23, 2005 8:17 am |
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Hi all,
I've worked with the LF parts before and seem to remembered the ccs ICD program which I use to program parts used to report the part correctly as a "18LF452".
I have just programmed a batch of 10 boards; the ICD is reporting the part as a 18F452 but I ordered the LF part and indeed this is what is screen printed onto the package!
Quick questions is my memory playing tricks with me (not the first time!)? Can the ICD distinguish the LF parts? Or have a got a rouge batch of LF parts and they are actually F parts!
Any ideas?
Keep well,
Will |
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PCM programmer
Joined: 06 Sep 2003
Posts: 21708
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| Posted: Wed Mar 23, 2005 1:39 pm |
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I have a board here with a 18LF452 in it.
The data sheet and the programming guide don't show a separate
device ID for LF chips.
I attached an ICD2 with MPLAB 7.01 to the board, and selected "connect".
It displayed this:
Target Device PIC18F452 found, revision = c0 |
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Will Reeve
Joined: 30 Oct 2003
Posts: 209
Location: Norfolk, England
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| Posted: Wed Mar 23, 2005 1:48 pm |
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Thanks, means it was in my imagination last time!
Does make you wonder if there is any difference between the F and LF parts...the cynic in me wonders if it's just an excuse to charge a little more...
Keep well,
Will |
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jds-pic
Joined: 17 Sep 2003
Posts: 205
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| Posted: Fri Mar 25, 2005 10:39 am |
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| Will Reeve wrote: | Does make you wonder if there is any difference between the F and LF parts...the cynic in me wonders if it's just an excuse to charge a little more...
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will,
did you read and compare the datasheets for the two devices?
especially the section regarding operating voltage range?
jds-pic |
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bluetooth
Joined: 08 Jan 2005
Posts: 74
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| Posted: Fri Mar 25, 2005 10:45 am |
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Microchip's website specifically states that the LF parts are tested to different specs to get lower voltage operation. They also say that the dies between the two are identical - so they *should* program the same.
When I connect to an 18LF2520 it tells me that it connected to an 18F2520 Rev 0x1.
There's another thread on this nearby..... I found out some interesting things yesterday. |
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Will Reeve
Joined: 30 Oct 2003
Posts: 209
Location: Norfolk, England
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| Posted: Fri Mar 25, 2005 11:13 am |
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I did read the data sheet, it's the voltage range which caused me to use a LF part (the device runs from 3 AA's).
I just wondered if all PIC's are the same and Microchip is doing a "Intel" and marking up some as LF and charging a premium.
It appears they do actually test them all and those which are within "LF" spec get a LF stamp....trouble is what if the manufacturing is so good they are all within the LF spec?
Keep well,
Will |
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Hans Wedemeyer
Joined: 15 Sep 2003
Posts: 226
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| Watch out for the other problem |
| Posted: Fri Mar 25, 2005 1:14 pm |
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| If the fuses need to be erased, it cannot be done with less than 5V. |
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Mark
Joined: 07 Sep 2003
Posts: 2838
Location: Atlanta, GA
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| Posted: Fri Mar 25, 2005 4:17 pm |
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| You are partly paying for the extra testing. |
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bluetooth
Joined: 08 Jan 2005
Posts: 74
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| Posted: Fri Mar 25, 2005 4:37 pm |
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Will:
If you believe they're all the same, simply buy the cheaper parts. But I'd keep my resume updated if I did that....  |
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Will Reeve
Joined: 30 Oct 2003
Posts: 209
Location: Norfolk, England
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| Posted: Wed Mar 30, 2005 9:40 am |
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The circuit it programed and tested at 5v so I will be ok for fuses. I wanted to get a bit more life out of a set of batteries, the whole circuit runs OK down to about 3v which is good enough for me.
Keep well guys,
Will |
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