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'Some (perhaps) easy newbie questions...'
1998\12\20@235331 by Greg Cormier

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Hey there. I just got on the list yesterday... "Holy volume Batman!". But
anyways, I have a few little questions which I've been unable to get
answers to, maybe you guys can help out.

- While reading through projects / literature on the 16x84's, all this talk
comes up about EEPROM, but I feel like it's not just how it can be erased
through the programmer. Does the 84 have some sort of memory programmable
while the chip is in the application circuit (at runtime)??

- Is there a list of mnemonics for MPASM. I must of been through every .PDF
file I can find...

- Why shouldn't TRIS be used on the 84's? I got a compiler warning when I
used it. How should I set the ports then?

- Is there a true answer to finding a cheap source for PIC's in small
quantities? I've been to a few places, DigiKey, Future, Electrosonics, they
are all around 15 bucks for a single C84.

- Can someone explain the relationship between the clockspeed and MIPS? And
how to calculate how long (in nS or uS or whatever) an instruction will
take to perform? Maybe a simple timing FAQ or something would do the trick....

Thanks!
Greg


-----------------------
Greg Cormier
Kathmandu, Nepal
Local time : GMT + 5h30m
spam_OUTgcormierTakeThisOuTspamwlink.com.np
ICQ # : 565465

1998\12\21@003629 by Jim Robertson

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face
At 07:38 21/12/98 +0200, you wrote:
>Hey there. I just got on the list yesterday... "Holy volume Batman!". But
>anyways, I have a few little questions which I've been unable to get
>answers to, maybe you guys can help out.
>
>- While reading through projects / literature on the 16x84's, all this talk
>comes up about EEPROM, but I feel like it's not just how it can be erased
>through the programmer. Does the 84 have some sort of memory programmable
>while the chip is in the application circuit (at runtime)??

Yes, 64 bytes of data EEPROM. Note that the "FLASH" parts are really EEPROM
too. Data EEPROM is read/writable at program time and run time.

Program memory cannot be programmed by the '84 itself.

Note there are newer pics with Data EEPROM that can only be programmed/read
by the PIC at run time.  This is a security measure.

>- Is there a list of mnemonics for MPASM. I must of been through every .PDF
>file I can find...

Look harder. The mnemonics are listed in a table in all of the PIC data
sheets.
Are you looking for something else or something better?


>
>- Why shouldn't TRIS be used on the 84's? I got a compiler warning when I
>used it. How should I set the ports then?

The TRIS ports can be directly read and written to. They are in bank 1 so you
need to set a bit in the status register like this.

BSF STATUS, RP0

access TRIS ports here.

BCF STATUS,RP0

The advantage of this is that you can set the I/O pins individually with
BSF and BCF instructions.

Microchip have been warning people not to use the TRIS instruction for YEARS.
Few people take any notice now.

Also note that there are NO "TRIS instructions" for ports D, E, F and
perhaps C.
(Can't remember)    This is a good reason for not using the TRIS instruction.


>- Is there a true answer to finding a cheap source for PIC's in small
>quantities? I've been to a few places, DigiKey, Future, Electrosonics, they
>are all around 15 bucks for a single C84.

Wow! I will sell 'em MUCH cheaper than that.

>- Can someone explain the relationship between the clockspeed and MIPS? And
>how to calculate how long (in nS or uS or whatever) an instruction will
>take to perform? Maybe a simple timing FAQ or something would do the
trick....

Well if I can be very terse about it...

On a pic MIPS = Clock/4 Well almost. Jumps, calls and any other instruction
that
modifies the program counter take two clock cycles, (8 clocks.) This lowers
the
MIPS a little but generally you get the picture.


Jim

{Quote hidden}

--------------------------------------------------------
Jim Robertson
Email: newfoundspamKILLspampipeline.com.au

http://www.pipeline.com.au/users/newfound
--------------------------------------------------------

1998\12\21@211605 by Herb Montes

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face
At 07:38 AM 12/21/98 +0200, you wrote:
>Hey there. I just got on the list yesterday... "Holy volume Batman!". But
>anyways, I have a few little questions which I've been unable to get
>answers to, maybe you guys can help out.
>
>- Is there a true answer to finding a cheap source for PIC's in small
>quantities? I've been to a few places, DigiKey, Future, Electrosonics, they
>are all around 15 bucks for a single C84.
>
>Thanks!
>Greg
>

Jameco (http://www.jameco.com) sells the 16C84 for $6.95 and the 16F84 for $5.95
in single quantities.

-Herb

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