New Microchip PIC processor.

[Bill the arcstarter]

Ludis Langens <ludis at cruzers.com> wrote:

>>http://www.microchip.com/10/Lit/PICmicro/16F87X/index.htm
>
>These chips are proposed for the PIC based EPROM emulator over on gmecm.  
>(BTW, drawing my proposed schematic for the emulator is bubbling up to the 
>top of my priority queue.)

Do you have a url for that project?

>>i/o out the wazoo

>33 I/O lines maximum isn't a lot, especially with the way that Microchip 
>scatters the built-in peripherals onto these pins.

I suppose "wazoo" is a relative term. :)  Of course you can get as many as 
you need via the old shift register technique...

>>2) Allowed the processor to read/write the program space at runtime.  This
>>would be very useful for fuel maps and the like.  Prior to this processor 
>>-
>>that sort of thing would have required addition components.

>AFAIK, every PIC has been able to have data tables in the built-in "ROM" - 
>- using the "return and load W" opcode.

True - but this new family allows you to (on the fly) WRITE to program 
space!  This would (could?) be used for modding maps on the fly w/o a 
separate programming module, EPROM emulator, etc...  You also can  directly 
access the program space via the Flash SFR registers - don't have to use 
that awkward "computed goto" return-W cludge! :)

Looks like there is some form of half-bank memory protection.  This would 
prevent a software glitch from overwriting the executable portion of the 
program space.  You could put the r/w maps up in the less protected area and 
leave the area containing the program protected.

Write time to the code space is 4-10 msec per byte.  No page mode available 
:(

Spoke to a microchip rep today who claims that shipments of ALL of those 
families (16F873,4,6,7) starts June 11th.  Several specific parts (probably 
the smaller die parts with less memory?) have been in production for several 
months, and have shipped in excess of 10K parts.  Looks like this thing is 
for real - no more "vapor".

-Bill


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