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PICList Thread
'HELP::Getting a 16F877 up and running'
1999\07\03@170936 by Aaron Martin

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Guys,
   I have successfuly gotten a 16F84 up and running and made an attempt
at getting
a 16F877 up, but I'm stumped.

The pic is programmed correctly (verified using a protoboard, I am
blinking Port D.0 through D.2)

I wired it up using the same "concept" as the 16F84:
   OSCin/OSCout (pins 13/14) to a Crystal (same crystal that I used on
my 16F84, 10mhz).  With 22pf caps to ground.
4.7k resitor to +5v on Pin 1 for MCLR.  +5v on pins 11 and 32 with a
.1uf cap to ground. 12 + 31 to ground.
I then wired pin 21 (Port D.2) to a 470 ohm to a led...

   I don't see any voltage change on port D at all...as if either no
clocks are running, or the chip is in reset... OR I
don't know about something else I should have wired up... Anyone have
any ideas?
       -- Aaron

1999\07\03@185459 by Don McKenzie

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Aaron Martin wrote:
>
> Guys,
>     I have successfuly gotten a 16F84 up and running and made an attempt
> at getting
> a 16F877 up, but I'm stumped.
>
> The pic is programmed correctly (verified using a protoboard, I am
> blinking Port D.0 through D.2)

snip---

follow the link: SimmStick Student Projects from:
http://www.dontronics.com/vicuni.html
to get to: Programming the PIC16F877 on a SimmStick.
and you may find it in the init code.

Don McKenzie  spam_OUTdonTakeThisOuTspamdontronics.com http://www.dontronics.com

Don's Download Dungeon:   http://www.dontronics.com/download.html
Australian Electronics Ring http://www.dontronics.com/aering.html
Win $500USD Cash. Micro design contest:  http://www.simmstick.com

1999\07\03@205748 by ronruss

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The config register for the 877 has more bits that need to be 'set'
than the 84. You might have problems using an 84 programming software
to program the 877. Try the updated programming software from
http://www.picwiser.com.

Aaron Martin wrote:

{Quote hidden}

--

From: Ron Russ
  EMICROS  - Embedded Micro Software
 (http://www.emicros.com)
  CANPORT  - Lowest cost PC to Controller Area Network Adapter
 (http://www.emicros.com/canport.htm)
  CANTEC11 - 68HC11 SBC with Controller Area Network
 (http://www.emicros.com/cantec11.htm)

1999\07\03@231702 by Jim Robertson

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At 16:09 3/07/99 -0500, you wrote:


Make sure that either the LVP config bit is programmed as '0' or ensure
that port b.3 (pin-36) is grounded at all times.

Tony, are you reading this? This may well be why your 16F877 emulated a
piece of plastic. I have been thinking about this for a while.

Jim



{Quote hidden}

________________________________________
Email: .....newfoundKILLspamspam@spam@pipeline.com.au
http://www.new-elect.com
WARP-13 SALE now on. $48USD with world delivery.
MPLAB compatible PIC programmers and firmware
upgrades for many programmers.
________________________________________

1999\07\03@233400 by Don McKenzie

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Jim Robertson wrote:
>
> At 16:09 3/07/99 -0500, you wrote:
>
> Make sure that either the LVP config bit is programmed as '0' or ensure
> that port b.3 (pin-36) is grounded at all times.
>
> Tony, are you reading this? This may well be why your 16F877 emulated a
> piece of plastic. I have been thinking about this for a while.
>
> Jim

port b.3 (pin-36) is grounded at all times Young Jim?
Is "at all times" really mean "at all times"?

I don't like the sound of this.

Don McKenzie  donspamKILLspamdontronics.com http://www.dontronics.com

Don's Download Dungeon:   http://www.dontronics.com/download.html
Australian Electronics Ring http://www.dontronics.com/aering.html
Win $500USD Cash. Micro design contest:  http://www.simmstick.com

1999\07\04@071525 by paulb

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Don McKenzie wrote:

> port b.3 (pin-36) is grounded at all times Young Jim?
> Is "at all times" really mean "at all times"?

 Note carefully what he said.  "Make sure that *either* the LVP config
bit is programmed as '0' *or* ensure that port b.3 (pin-36) is grounded
at all times."

 It appears that *if* you enable the Low Voltage Programming mode then
for whatever random reason it suits them to dedicate B.3 to this
function. Pull it high and you are in programming mode.

> I don't like the sound of this.

 Well, Tough!  This just led me to look into the datasheet.  It's very
"Microchip" if you take my point.  It *still* contains the disclaimer:
"To maintain upward compatibility with future PIC16CXXX products, _do
not use_ the OPTION and TRIS instructions."

 Which means of course, that despite their exclusion from the command
summary, those instructions are most certainly *still* there and thus
the *preferred* (easiest) way to access those registers.  Again, *very*
Microchip (Orwellian).

 But that's not all!  There may be a reason I have yet to find, but
get this, PORTB and TRISB and *only* those port registers are now
aliased in Banks 2 and 3.  The thot plickens!

 And I've only just begun to delve into the datasheet!
--
 Cheers,
       Paul B.

1999\07\04@090856 by Byron A Jeff

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>
> Jim Robertson wrote:
> >
> > At 16:09 3/07/99 -0500, you wrote:
> >
> > Make sure that either the LVP config bit is programmed as '0' or ensure
> > that port b.3 (pin-36) is grounded at all times.
> >
> > Tony, are you reading this? This may well be why your 16F877 emulated a
> > piece of plastic. I have been thinking about this for a while.
> >
> > Jim
>
> port b.3 (pin-36) is grounded at all times Young Jim?
> Is "at all times" really mean "at all times"?

It means at all times during normal operation if the LVP bit is set, which
it is by default.

It's a great idea. 5V only programming. No programmable voltage supply.
Pull you voltage from the PC keybard port, which is what I've done with my
homemade programmer (along with the 2 9V batteries for the high voltage
programmable supply)

Unfortunately the placement of the now dedicated pins to select programming
mode was poor. It's right in the middle of a perfectly good 8 bit port.
it must be grounded during normal operation and cannot be used as either
an input or output.

It certainly would have been better if this pin had been located either on
one of the two non 8 bit ports (A or E) or if it had to be an 8 bit port
at least place it at one end of the other so that a contigouous 7 bit port
could be formed.

>
> I don't like the sound of this.

It's isn't a major disaster. Simply clear the LVP bit in the config word the
first time you program the part (using the normal high voltage programming
algorithm, which works all the time BTW) and you get port b.3 back for
normal operation.

It just would have been nicer if that pin had been placed a bit more out the
way since in LVP mode it's totally out of commission during normal operation.

BAJ

1999\07\04@123453 by Aaron Martin

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Turns out I got the 16F877 up and running.  Here were my bugs:
   Pins 1 & 2 touching.
   NEeded to change the OSC type from XT to HS.

   Thats all..and Pin B.3 is floating.
       -- Aaron

Jim Robertson wrote:

{Quote hidden}

1999\07\04@182853 by paulb

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Aaron Martin wrote:

>     Thats all..and Pin B.3 is floating.

 Well, I hope you have programmed it as output then, like all unused
and therfore unconnected pins.
--
 Cheers,
       Paul B.

1999\07\04@184134 by Don McKenzie

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Paul B. Webster VK2BZC wrote:
>
> Don McKenzie wrote:
>
> > port b.3 (pin-36) is grounded at all times Young Jim?
> > Is "at all times" really mean "at all times"?
>
>   Note carefully what he said.  "Make sure that *either* the LVP config
> bit is programmed as '0' *or* ensure that port b.3 (pin-36) is grounded
> at all times."

**or** Hmmm....

OK Paul, at my age you don't have to tell me more than twice, well... 3
or 4 times tops!

You must get up as early as me, I really wonder where you find the time
for all that doctoring stuff?

Don McKenzie  EraseMEdonspam_OUTspamTakeThisOuTdontronics.com http://www.dontronics.com

Don's Download Dungeon:   http://www.dontronics.com/download.html
Australian Electronics Ring http://www.dontronics.com/aering.html
Win $500USD Cash. Micro design contest:  http://www.simmstick.com

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