Hello Nikolai,

04 Sep 96, zan@logika.spb.su writes to all:

 P> I am starting up to study PIC microcontrollers and I don't know which
 P> programmer to buy.

 P> PICSTART+ : Does fit well for me if I intended to programme 100-150
 P> chips per month? (i.e. for a serial product)
 P> May be PRO MATE? But may be not worth to spend money? I don't
 P> understand what does it give really...quality programm?
 P> ...verifications? or still anything?

The main difference between development programmers (PICSTART+, COMPIC-1/5X and
 many others) and production quality programmers (PROMATE-II, COMPIC-PRO and
 also some others) is variable Vdd and Vpp during programming and verification.

As noted at Microchip's programming specifications, for production
quality programmers Vdd should be varied from 2.0 till 6.5V with 0.25V
 granularity (DS30190D, p.3), Vpp should be varied from 12 till 14V with
0.25V granularity (DS30337A, p.1).

The main reason for variable Vdd is the following: Vdd in the real device can
be different, than during programming/verification.

Below is very simplified description.
For example, you want to have Vdd=6V in some application. You program PIC on the
 development programmer with Vdd=5V. For example, some cells programmed to the
 2.8V level. This cells readed as "1"(programmed) at Vdd=5V, but possibly will
 reads as "0"(unprogrammed) at Vdd=6V. This will lead to hard-to-find errors (I
 have this experience).
Second case. You want to have Vdd=2V. In this case some program cells,
readed as "0"(cleared) at Vdd=5V, possibly will reads as "1"(non-cleared)
at Vdd=2V. This error occurs, when you partially clear UV erasable development
chip. For example, some cells cleared to the 1.5V level. It reads fully cleared
 at Vdd=5V, but reads as "1" at Vdd=2V.

Conclusions: You can use development programmer, if you use Vdd=5V+-5% in your
             applications. You should use production quality programmer in any
             other cases.

Best regards.

Alexej Vladimirov  avlad@mail.ormix.riga.lv
http://www.ormix.riga.lv/eng/mchip/mchip.htm
...more than 160 Microchip-related links now...

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