On Tue, 30 Sep 1997 14:01:44 +0200 courche <courche@CHEZ.COM> writes:

>I seach a method to program PIC without use of internal EPROM. I seach
>a
>method to produce the code into an EEPROM like 28C64 and PIC can
>execute
>the prog whitch burns into the EEPROM... I d'ont whant to use 10 PIC
>to
>debug final program and wait for the EPROM eraser after my 10 PIC was
>burned !.

Only the PIC17Cxx chips can execute from external program memory.  The
vastly more popular and less expensive 16XX line doesn't.  You can use a
PIC16F84, which has internal EEPROM program memory so it can be reused
immediately.  Put your first few projects in with 16F84's to become
familiar with direct to PIC programming.

This works fine until you need the extra pins or features of some other
PIC16CXX.  The other PIC16's have EPROM program memory, which must be
erased with UV light.  I've found it effective to cycle 3 erasable PICs
through programming and erasing.  One PIC is in the circuit while the
other 2 are in the UV eraser.  Set the timer on the eraser to slightly
longer the minimum time it takes to make a PIC "blank".  With a good new
eraser this is about 3 minutes.  When you need to try a new program, take
the PIC out of the circuit and put it in the eraser, take out the PIC
which has been in the eraser the longest (which has been erased twice so
it is reasonably reliably blank) and use it.  When the erase cycle is
done the other PIC in the eraser has been erased fully, the one just put
there only once.  This way you have access to a blank PIC about every 3
minutes.  Obviously, "pipelining" more PICs in the eraser could speed up
the process even more but 3 minutes is about right.