Home  Products Prices Site Map Order Contact What's New Books Free Files Links FAQ
Dontronics Home Page Pigmy Boards Assembly Part 1.
Bottom of Page

PIGMY Boards: Sold out 4-Apr-99

For reference only.
Part 1 of 2....     Revision B.

These instructions are in two parts. Please read both sections.

A full diagram of jumper and header configuration for FED Basic is
given in a later part of these instructions.

My Revision B. PIGMY board can now be used to support FED Basic,
Basic Stamp 1 Interpreter chip (my BasicMicro-1), Basic Stamp 2
Interpreter chip, my PICEX network Controller, and possibly VersaTech
FBasic TicKit.

Basic Stamp 2 and FBasic are yet to be tested.

Parallax, the Parallax logo, BASIC Stamp, and PBASIC are trademarks of
Parallax Inc. PIC is a registered trademark of MicroChip Technology

My BasicMicro-1 uses the Parallax Stamp Basic 1 interpreter chip and
is a Basic Stamp 1 work-alike.

All options and usage of the PIGMY circuit are covered in this

My PIC16C84 "DT001" programmer connection is covered as well.

This board also has provision for RS-485 communications. This can be 1
or 2 ports of 2 wire or 1 port of 4 wire. This is used for long
distances up to 4000 feet.

You could use this board as an RS-232 to RS-485 converter board and
forget about the PIC stuff if you like. It has its own power supply
and everything you need for this conversion. See a full section on
this topic later.

                Before you assemble anything, READ THIS...

    There are 3 links on the component side of the board that must be
    installed if you wish to use this board for an 18 pin PIC chip. These
    are the 3 links that are inside the E1 outline. Just above E2.

    There is another link inside both the E1 and E2 outline that is used
    for the E5 EEPROM. If you are unsure, I strongly suggest you install
    this one as well.

    If you are building this board up as a general purpose experimental
    and possible programming board, fit all sockets, links and all headers
    so that you can configure any and all options. Instructions on these
    options will be added to the end of this article as these circuits are
    developed and proven.

    Cheap Comms:
    Transistor Q3 is shown incorrectly on the overlay and PIGMY board.
    The flat side should be shown in the same directions as Q2 and Q4.
    This also means that you will need to bend the centre leg of this
    transistor in order to fit it into the board in the correct direction.
    Don't install R23 (10K). Because of the brown-out circuit, reset will
    never work with R23 installed, so ignore it.

If you are going to use RS-232 communications via the DB-25 pin
socket, you have two options. (MAX) or (CC)

1) (MAX) Use the MAX-232 IC and caps C8, 9, 10, and 11. It's simple to
         install, has true RS-232 levels, but may be expensive.

2) (CC)  Cheap Circuit. Couldn't think of a nicer name, but it
         explains the circuit well. Uses discrete components and
         steals the negative voltage from the existing RS-232 signals.
         Seems to work fine with modern serial ports over short
         distances. If interfaced to other 'cheap' RS-232 ports, you
         may experience problems.


As we move into this project, I will use a set of abbreviations to help
simplify the explanation of these instructions. These are enclosed in

(BS1)    This is the Parallax Basic Stamp 1 Interpreter chip support
         circuit. This is an 18 pin PIC device. I call it my
         BasicMicro-1 which is a BS1 work-alike. Uses a PIC16C56/XT,
         and a 93LC56 (256 byte EEPROM).

(BS2)    The Parallax Basic Stamp 2 Interpreter chip support circuit.
         This is a 28 pin PIC device. Uses a PIC16C57/HS, and a
         24LC16B (2K EEPROM). I haven't tested this as I have moved
         onto FED Basic. All feedback appreciated.

(FED)    FED PIC Basic can be a PIC chip in either an 18 pin or 28 pin
         package. Uses a large range of PIC devices and a choice of 2K
         or 8K EEPROM which is link selected.

(FBasic) I think this uses a 57 and a choice of 2K or 8K EEPROMs. I
         still wait on promised info from the manufacturers, but think
         I have been forgotten about, or perhaps my package has gone

(ATN)    This is an added signal and is used only for (BS2). You don't
         need to install it or any associated components for other

(MAX)    Uses MAX-232 chip and associated components for serial comms.

(CC)     Uses Cheap Circuit components for serial comms.

(CC/RA)  Four components make up the Robin Abbott portion of the cheap
         comms circuit. Some computers may not work with these items.
         I suggest you try the circuit without them first, as it seems
         to work fine. BS2 only has a resistor between RX and TX
         RS-232 signals.

(PICEX)  This is my serial network controller that uses a programmed
         57/XT, and 4Mhz crystal for 9600,N,8,1 comms. A simple EZ-6
         command language designed by me, is used for full control.

(84PGM)  Header J11 is used for in-circuit serial programming of
         suitable PIC devices and mates with my Cheap PIC84

(RS-485) An added option for long distance (4000') communications. A
         single 2 wire, or 2 by 2 wire, or 1 by 4 wire circuit can be

(XTL)    The support circuitry for crystal operation.

(R/C)    The support circuitry for Resistor/Capacitor clock operation.
         (Non-crystal operation).

(OPT)    These components are optional and can be installed to suit
         individual requirements.

(ALL)    These items must be installed for all projects.

I will now give you a complete list of all components for building up
this board with all options. More detailed assembly is given to each

The main PIGMY board on its own, that is, without driving heavy loads
from the on-board power supply, will run from a 9 Volt battery for a
reasonable time.

I have used the Australian Dick Smith Electronics Catalog(ue) numbers
as a reference only.

Components: (Not all required for any one project).

Plug-pack 9 to 12 volts AC or DC at 50ma to 100ma. The current
required to run the PIGMY board is very small. If you need to run 8
relays off the same supply, a 1AMP Plug-pack can be used. Experienced
builders may prefer to use a suitable AC transformer. (DSE Cat M-2155
9.5VAC multi-tap @ 1A)

A "U" shape type heat sink to suit the regulator should be used if you
are running at more than about 250ma. This regulator is rated at 1.5

1 by PIGMY Printed Circuit Board.                               (ALL)
1 by 4MHz (others up to 20Mhz) Crystal.                         (XTL)
1 by 18 or 28 pin PIC Microcontroller.   (E1, or E2)
1 by 93LC56 Mchip EEPROM. (8 pin DIP)    (E3)                   (BS1)
1 by MAX-232 RS-232 Level Converter.     (E4)                   (MAX)
1 by 24LC16B 2K Mchip EEPROM (8 pin DIP) (E5)                   (OPT)
1 by 24LC65  8K Mchip EEPROM (8 pin DIP) (E5)                   (OPT)
2 by 75176B  TTL to RS-485 Converters.   (E6,E7)                (RS-485)

Dick Smith also has both the MAX-232 and 4Mhz Crystal in his Catalogue.

1 by 7805         +5  Volt regulator in TO-220 case.            (ALL)
1 by Diode Bridge D1  WO2 or WO4 type.    (DSE Cat Z-3304)      (ALL)
1 by 1N4004       D2  (Detect AC 50/60hz for RTCC).             (OPT)
1 by 1N4148       D3  Small signal diode.                       (CC/RA)

1 by Capacitor    C1  1000uf Electro @16 Volts. PCB type mount. (ALL)
1 by Capacitor    C2  .01uf (or .1uf) Ceramic                   (ALL)
1 by Capacitor    C3  .01uf (or .1uf) Ceramic                   (ALL)
1 by Capacitor    C4  10uf Electrolytic PCB mount. @16 Volts.   (ALL)
1 by Capacitor    C5  15pf Ceramic                              (XTL)
1 by Capacitor    C6  22pf Ceramic                              (R/C)
1 by Capacitor    C7  15pf Ceramic                              (XTL)
1 by Capacitor    C8  1uf Electrolytic PCB mount. @16 Volts.    (MAX)
1 by Capacitor    C9  1uf Electrolytic PCB mount. @16 Volts.    (MAX)
1 by Capacitor    C10 1uf Electrolytic PCB mount. @16 Volts.    (MAX)
1 by Capacitor    C11 1uf Electrolytic PCB mount. @16 Volts.    (MAX)
1 by Capacitor    C12 .01uf (or .1uf) Ceramic                   (ALL)
1 by Capacitor    C13 .01uf (or .1uf) Ceramic                   (RS-485)
1 by Capacitor    C14 .01uf (or .1uf) Ceramic                   (RS-485)
1 by Capacitor    C15 100uf Electrolytic PCB mount.@16 Volts.   (CC/RA)

(A total of 15 Caps, 7 of these are polarized.)

1 by Resistor     R1  330K .25 W Detect AC 50/60hz for RTCC.    (OPT)
1 by Resistor     R2  4K7  .25 W RTCC Pullup.                   (ALL)
1 by Resistor     R3  2M2  .25 W Brownout.                      (ALL)
1 by Resistor     R4  2M2  .25 W Brownout.                      (ALL)
1 by Resistor     R5  470K .25 W Brownout.                      (ALL)
1 by Resistor     R6  4K7  .25 W For Resistor/Capacitor clock   (R/C)
1 by Resistor     R7  330  .25 W Power LED current limit.       (OPT)
1 by Resistor     R8  4K7  .25 W Data line to 93LC56            (BS1)
1 by Resistor     R9  330  .25 W LED 3 current limit.           (OPT/FED)
1 by Resistor     R10 330  .25 W LED 2 current limit.           (OPT)
1 by Resistor     R11 330  .25 W LED 1 current limit.           (OPT)
1 by Resistor     R12 330  .25 W LED 0 current limit.           (OPT)
1 by Resistor     R13 22K  .25 W EEPROM SDA pullup.             (OPT)
1 by Resistor     R14 22K  .25 W EEPROM SCL pullup.             (OPT)
1 by Resistor     R15 22K  .25 W                                (CC)
1 by Resistor     R16 300  .25 W                                (CC/RA)
1 by Resistor     R17 2K7  .25 W                                (CC/RA)
1 by Resistor     R18 22K  .25 W                                (ATN)
1 by Resistor     R19 2K2  .25 W                                (ATN)
1 by Resistor     R20 4K7  .25 W Select 2K/8K EEPROM.           (FED)
1 by Resistor     R21 22K  .25 W                                (CC)
1 by Resistor     R22 10K  .25 W                                (CC)
1 by Resistor     R23 10K  .25 W ****Don't Install, Ignore****  (ATN)
1 by Resistor     R24 10K  .25 W                                (RS-485)
1 by Resistor     R25 10K  .25 W                                (RS-485)
1 by Resistor     R26 2K2  .25 W                                (ATN)
1 by Resistor     R27 100  .25 W In line MCLR for serial Burn.  (ALL)

1 by Transistor   Q1  BC558 Any PNP S Signal Amp. Brownout cct. (ALL)
1 by Transistor   Q2  BC548 Any NPN                             (CC)
1 by Transistor   Q3  BC558 Any PNP ****Direction Incorrect**** (CC)
1 by Transistor   Q4  BC548 Any NPN                             (ATN)

1 by DB-25 Female Solder Tail connector. RS-232                 (OPT)
1 by DB-25 Female Solder Tail connector. RS-485                 (RS-485)

1 by 2 Post PCB screw terminal. 5mm or 5.08mm centres. Power In (ALL)
1 by 2 Post PCB screw terminal. 5mm or 5.08mm centres. Pwr out  (OPT)
1 by 26 pin IDC type Male header. (2 by 13 pins) J1             (OPT)
1 by 34 pin IDC type Male header. (2 by 17 pins) J2             (OPT)
5 by 5mm LEDs.                                        &p;         (OPT/FED)


If this is your first PIGMY board assembly, I strongly suggest you use
machine pin sockets for all IC's. Cheaper sockets can be used on later
models when you get the feel of what you need for each project.

Production version boards may use no sockets at all.

If you are going to install both E1 (28 pin) and E2 (18 pin) sockets,

you will need to install the 18 pin socket first. (Don't forget the
link under this socket).

Two 14 pin strips then needed to be soldered into the E1 holes. These
can be machine pin strips or a cut down machine pin socket. A little
bit of trimming with a scalpel or file may be in order.

If you are fitting only a 28 pin socket then this will fit straight into the
E1 holes. (Once again, don't forget the one link).

Another good thing about machine pin sockets is that you can easily convert
them to a Zero Insertion Force (ZIF) without soldering at a later stage if

Get any cheap single contact socket that will allow the ZIF socket to be
pushed hard into it. Insert this new combination into a machine pin socket.
You now have a ZIF socket with machine pins. A unit that can be pushed into
any target socket, then removed without damage to the PCB socket.

1 by 28 pin DIP socket. (E1) PIC Microcontroller
1 by 18 pin DIP socket. (E2) PIC Microcontroller
1 by  8 pin DIP socket. (E3) 93LC56                             (BS1)
1 by 16 pin DIP socket. (E4) MAX-232                            (MAX)
1 by  8 pin DIP socket. (E5) 24LC16B or 24LC65       (FED,BS2,FBasic)
1 by  8 pin DIP socket. (E6) 75176B                          (RS-485)
1 by  8 pin DIP socket. (E7) 75176B                          (RS-485)

Lots of single and dual strips of male IDC headers and test links will
be needed to make this board fully flexible for all projects. If you
are building up the board for one project only, wire links can be used
instead of the male posts and test links.

    Before going further I will mention groups of components and what
    circuit they are used for:

    Resistor/Capacitor clock instead of Crystal.
    J4 and J5 male pins and links.
    1 by Capacitor    C6 22pf Ceramic
    1 by Resistor     R6 4K7  .25 W
    If you are using a Crystal, (all my projects do), then you don't need
    these components. Just link J4 pins 2 and 3, and J5 pins 2 and 3.

    50/60hz INT for RTCC. (Not required in any of my projects).
    J3 male pins and link.
    1 by Resistor     R1  330K .25 W
    1 by Diode        D2  1N4004
    Unless you wish to read the 50/60hz timing, you can ignore these
    components and just link J3 pins 1 and 2 together.

    PARALLAX Basic Stamp work-alike, BasicMicro-1.
    J7 A strip of 3 male pins for comms to IBM Compatible PC printer port.
    1 by Resistor     R8  4K7  .25 W (and Local test on PICEX)
    1 by PIC16C56-XT  E2  Programmed Basic Stamp  ;Available from Don.
    1 by 18 pin DIP socket to suit E2.
    1 by 93LC56       E3  EEPROM
    1 by 8 pin DIP socket to suit E3.

    Power out connections. (Possible power to relay board.)
    1 by 2 Post PCB mount screw terminal. 5mm or 5.08mm centres.
    Can also be used for +12 V POWER-IN to board. (Bridge not needed.)

    J11 10 pin IDC male Header.
    Programming connection for my DT001 programmer.

Before installing any components, you will need to use a file to bevel
a slight 45 degree angle along the DB-25 connector tracks so that the
DB-25 connectors will push hard onto the board without damage. This
may need to be done on both sides of the board to ease these
connectors on. Don't install these connectors yet.


Several links must be installed on the component side of the board.

The component side of the board is the side that doesn't have the
tracks. It is the blank side of the board.

The other side is the solder side. All soldering is done on the solder
side of the board.

All components are fitted from the component side of the board.

If you have trouble understanding this, you may need assistance to
assemble this board.

I am very happy to assist on the phone if I can, but I can't build or
fault find to any great degree via a phone. I can assemble the board
for you, (at a price) if you wish.


You don't need all the links in for any one project, but you can put
them all in if you wish to. When building the board for a specific
need at a later date, you will find the link count will be well down.
Lots of options requires lots of links.

OK, you have installed the four links that fall inside the E1 outline.
                                          &nb                      (ALL)

Links 1 to 3 connect the 18 pin socket to the 28 pin socket signals
and must be installed when an 18 pin socket is used.

Link 4 jumpers +5V to E5.                             (FED,BS2,FBasic)


The link shown between J12 and C1 is also a ground connection. I
suggest that when you install this, you leave a little slack so that a
logic probe, Multi-Meter, or clip can be easily connected for testing
and experimenting. The link shown above the Reset button is a +5V
connection. Leave a little slack on this for the same reason. This
saves me putting in special GND and +5V posts as I have done with my
previous projects. These links must be installed at all times.   (ALL)


Install the two links near R6. Install the two links that run near the
top of J11.                                        &nbsnbsp;            (ALL)


Install the 3 links near pin 5 of E5. These jumper Ground to E5 and
the programming header J11.                     (FED,BS2,FBasic,PGM84)

Install the link one near J8. This connects ground to E3 and J7. (BS1)

Install the long link that runs between J1 and J2.               (ATN)


Install the link near Q2.                                      &n;  (CC)
and the one above E7.                                       sp; (RS-485)

That's a total of 17 links that you have installed so far.

There is a link that connects pins 6 and 8 together of the DB-25
female connector. This is used for my PICEX controller. You won't need
it for the Stamp work-alikes and FED Basic. If you do end up
installing this link, make it an insulated link that is connected over
the top of the DB-25 pin 20 link described below.              (PICEX)

Another link must be installed after the DB-25 Connector is soldered
in, but leave this link for now. It will connect pin 20 DTR of the
RS-232 DB-25 connector to the centre pin of J19.           (ATN/PICEX)

These following configuration links can also be soldered in or fully
optioned out with male pins and test links.

Crystal operation:
Solder a link at J4 between pins 2 and 3. That's the upper 2 pins.
Solder a link at J5 between pins 2 and 3. That's the upper 2 pins.

RTCC Normal operation:
Solder a link at J3 between pins 1 and 2. That's the 2 pins near the
7805 regulator.

MAX or Cheap comms: (FED, BS2, PICEX, FBasic) Not required for BS1.

Header J17 is used to select the DB-25 signals from a PC (or other
Micro), and direct them to either the Max-232 or the cheap comms

To select MAX, jumper J17 pin 3 to pin 5 and J17 pin 4 to pin 6. The
outputs will now appear at TTL levels at J14.

To select Cheap Comms, jumper J17 pin 3 to pin 1 and J17 pin 4 to pin
2. The outputs will now appear at TTL levels at J22.

A cable test loopback can be done to a PC by shorting out J17 pins 3
and 4 and running a comms program as a loopback test.

Further tests can be done on the hardware by shorting out the transmit
and receive on header J14 (MAX), or J22. (CC)

Assembling the PIGMY Printed Circuit Board as a PICEX Serial
Controller Network....

PICEX Serial Network Controller:

NODE is the PICEX board identification. Also known as the board number
or drop number.

This Node is burnt into the program of the PIC16C57-XT/P chip. It
can't be changed and is usually set by me as "DROP ZERO", however it
could be any number between 00 and FFHex. On request, I can make it
any number. If multiple boards are ordered together, these drops will
all be different.

Yes, it must be a 4Mhz crystal. This is the maximum clock frequency of
this version PIC chip and the software is designed for 9600 Baud.

Solder in your sockets first. Use machine pin types if you wish to.
Then solder in all of your resistors.

Solder in the Transistor Q1 BC558. Solder in Capacitors C1, C2, C3,
C4, C5, C7, and C12, plus the appropriate capacitors for your MAX/CC
choice of RS-232 circuits.

Watch out for the polarity of C1, and C4. These must be soldered into
the board the correct way around. The positive end of the Caps is
shown on the circuit overlay.

Solder in your 7805 regulator. This can be soldered in allowing for a
bolt and/or heat sink to be fitted at this position. Even if you don't
install a heatsink now, you may need one later on. I bolted a heatsink
to mine, soldered it in position, then removed it.

Solder in the Diode Bridge. The Positive leg is shown on the overlay.

Check the Reset button for pin identification. My artwork has the top
two pins connected together and the bottom two connected together.
Make sure that you solder this button in so that it operates

Solder in the 4Mhz crystal.

Install 3 LEDs (Power, L3, and L2) with the cathodes as shown on the

Install the J1 and J2 headers.

Install J6, J8, and J9 LED isolation headers, and the appropriate
shunts or links. These links are installed to allow the LEDs to be
used for power up diagnostics. If a low power application is required,
these links can be removed after final assembly and testing.

Install R8 and the J12 header.

Install the POWER-IN PCB mount screw terminals.

Install the DB-25 Female connector and the link that goes between pin
6, 8, and pin 20 on the other side of the board. A hole is provided to
get this one link from one side of the board to the other.

Make sure that you solder every connection of the DB-25 on the solder
side of the board. This will strengthen the board to connector "mate"
so that plugs can be pushed and pulled without damage to the board or

On the DB-25 connector, pins 4 and 5 need to be jumpered together.
This can be done by linking J18 pins 2 and 3 together.

Pins 6, 8, and 20 also need linking. The 6 to 8 link is on the
component side of the board as a simple wire link. This link could also
easily be done on the solder side of the board using a bare sigle wire link
and a nice bend over the single track between the two pads.

You will need to jumper pin 20 of the DB-25 to the via near pin 2 of J19. As
these last two links cross each other, one of them will have to be an
insulated wire. J19 pin 2 can be connected to J19 pin 3 to complete the pins
6, 8, and 20 circuit.

You also need to link up J17, the MAX/CC header selector to your
choice of RS-232 circuits as described elsewhere in this file.

The incoming signal must connect to RA1
The outgoing signal must connect to RA0.

To do this with MAX comms:
Connect J14 pin 1 to J15 pin 2. (RA1)
Connect J14 pin 2 to J15 pin 1. (RA0)

To do this with Cheap comms:
Connect J22 pin 1 to J15 pin 2. (RA1)
Connect J22 pin 2 to J15 pin 1. (RA0)

And apart from the two chips, I think that's it.

There are 4 pads on the board that don't seem to go anywhere.

These 4 pads will be used for 84 programming along with J11. Two of
these pads are right under R2. The other two are near J11. I have made
the 4 pads a black square on the overlay.

The resistor RX is only used for 20Mhz operation and can be ignored
for the PICEX circuit. If you needed it, the track would have to be
cut under RX and a 470 ohm resistor will be installed for RX.

                    POWER UP AND TESTING:

Before you power up, check with your multi-meter (on ohms) that ground
and +5 volts are not shorted together on the printed circuit board.

Don't install the chips yet. Connect up your power-pack, transformer,
or +9 Volt Battery. As the circuit has a diode bridge at the input, it
doesn't matter which way around you connect the positive and negative

Power up the unit and check that the +5 Volts is there before
proceeding. This is verified by the Power LED being on. Check the
volts with your multi-meter. This should read from about 4.8 to 5.1
Volts. That's what you get on 7805 regulators now days. Usually around
4.82 Volts with no load.

                      LOCAL POWER UP DIAGNOSTICS:

All OK? POWER DOWN and install chip E1, the PIC16C57-XT/P.


Still not sure of pin 1 of the male headers and chips? This is marked
on the overlay. Have a look at the text "J1". Next to it is a square
pin surrounded by a box. This pin is pin 1. All pin 1's on the overlay
are square. This includes the chips. All pin 1's are square on the
solder side of the board, that is, on the artwork.

Power up again and check the +5 volts.

Connect a 4K7 resistor between ground and RA0 of the circuit. The
easiest way of doing this is to link the J12 header.

R8 is only used for this test mode on PICEX, but used for the EEPROM
circuit on the Basic Stamp work-alike.

This signal, (RA0) is normally used for the serial out line. When
first powered up or reset, this pin is set to input and tested for the
4K7 resistor to ground. If the resistor is installed, the PICEX is
forced into the diagnostic routines. It doesn't matter if the MAX-232
is installed or not for this test.

If all is well, the L2 and L3 LEDs should be flashing off and on at a
1 cycle per second rate. These LEDs are actually doing a binary count
in the range of 0 through to 3, repeated over and over until you
remove the 4K7 resistor. During this time, all B and C ports are set
to low outputs and each output pulses high in turn for 1 second. This
is in sync with the L2 and L3 LEDs.

If you use one or two of my relay boards as LED monitors, you will see
this activity on these two ports. This diagnostic is a 16 cycle

I have noticed that if I use a 9V battery power supply, and the MAX-232
isn't installed, I don't need a 4K7 resistor to force the power up diags.

If the unit has passed this test, you are almost home. You can now install
the MAX-232 chip into the E4 socket before powering up again.

When the resistor is removed, PICEX restarts to normal operation and the LED
flashing routines stop. 

The MAX-232 has 400K pullup resistors on the TTL inputs, so this overcomes
the possibility of a false power up diagnostic running.

Connect a DB-25 male to DB-25 female cable to the PICEX female connector.
Connect this cable to the serial port of your PC. If you have a DB-9 male
serial connector, a standard DB-9 female to DB-25 male adapter will be

Power up your PICEX board and run a comms program on your PC. You must set
the comms program up as follows:

Baud rate: 9600, 8 Data bits, No Parity, and 1 stop bit.

Set Echo on. This will show all characters that you have typed.

To test the serial comms link TYPE ZZZZZZ. (6 Z's). You should get back from
PICEX the same 6 Z's.

The screen should look like this:


Unless a board is addressed, the message string that you send out is simply
returned. You should read through PICEX.CMD for more information on PICEX

To further test a single board, I have another diagnostic that requires 8 by
10K resistors wired up as follows:

RB0 to RC0 via a 10K, RB1 to RC1 via a 10K, etc, right up to RB7 to RC7 via
a 10K resistor. This wiring can be done on the top of a 26 pin header
connected to J1 or a 34 pin header connected to J2.

When this loopback arrangement is fitted, the "L" Command can be used as

"L" The Loopback Command:

This test was designed only for single unit assembly and testing on the
workbench. A network system will give weird errors, so only use it for
single unit testing.

The "L" command can get one of 2 answers from a live unit.

(1) LLLLLL 00>ERR   ;Loopback plug not fitted or hardware fault exists.
(2) LLLLLL 00>AOK   ;Unit 00 Tested OK.

Followed by this response from the active Node:

PICEX Version 1.0 by Don McKenzie
P.O. Box 595 Tullamarine 3043
Australia Phone (03)9-338-6286
Updated 12-Jul-94(c)

During this test, the RA2 and RA3 LEDs are toggled. The test sequence is as

LED RA2 OFF, LED RA3 OFF. These are cleared on entry to this test.

1 Second delay.
Test 1. Tests done with Port B as Output, and Port C as Input.

1 Second delay.
Test 2. Tests done with Port B as Input, and Port C as Output.

1 Second delay.
LED RA2 OFF, LED RA3 OFF. This unit passed the Loopback test.

If at any time an error is detected, a 1 second delay is followed by LED RA2
ON, and RA3 ON.

Good test, both LEDs are turned off.
Bad test, both LEDs remain on.

The LEDs can be cleared very easily with a 'M'aster reset or Reset button.

Any one into PIC design can set up a very simple stand alone tester using a
PIGMY board that outputs the 'L'oopback test (6 times 'L') when Reset is
pressed and software debounced. Results will be shown on the LEDs of the
unit under test.

The unit can now be tested with the full set of Commands as detailed in

End of Part 1.
What's Really HOT at Dontronics? 
Don's Download Dungeon
Home  Products Prices Site Map Order Contact What's New Books Free Files Links FAQ

Dontronics Home Page

Copyright © 1996-99 Dontronics
Top of Page