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Copyright © Matrix Multimedia Ltd.
Circuit description
The multiprogrammer solution is made up of two
parts: a circuit board that allows various slave PICmicro
devices to be programmed, and the Windows based
programming utility ‘PPP’.
1. Power supply
The board is normally operated from a regulated DC
supply of 13.5V or from a USB supply. This allows full
operation including programming. The board can be
operated solely from the USB cable provided. However,
care must be taken, as there is only limited power that
can be taken from a computer’s USB port.
The jumper link system, J11, allows the user to decide
on the source of the power supply. If using a regulated
13.5V power supply the jumper should be positioned to
the right hand side of the jumper system labelled ‘PSU’.
if using USB power, place the jumper on the left hand
side of the jumper system. LED D6 indicates that power
is supplied to the board from either the external power
supply or the USB cable.
Please note that both USB and the PSU cables should
be removed from the multiprogrammer board BEFORE
changing the position of this jumper.
Remember that other E-blocks will have to receive 5V
by placing a connecting wire from the “+V Out” screw
terminal of the multiprogrammer to the “+V” screw
terminal of each E-block that requires a voltage.
WARNING: Take extra care when wiring out the
+14V and +5V as if the wrong voltage is sent
to a downstream board it can permanently
damage the E-block.
2. Programming circuit
The multiprogrammer connects to a personal computer
via the USB socket. Any USB socket on the PC can be
used. The host microcontroller is used to communicate
between the USB bus and the multiprogrammer circuitry.
The host is connected to a network of analogue switches
formed by U4 and a charge pump circuit which is used
to multiply the 5V operating voltage up to the 13V
programming voltage. This circuitry routes 0V, 5V and
Vpp to appropriate pins on the slave PICmicro devices as
and when necessary.
The host has an on-board A/D converter that detects
the level of the supply voltage. LED 1 is used to indicate
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that the host is communicating with the PC and that the
connection with the PC is valid.
3. DIL sockets and I/O ports
The slave PICmicro DIL sockets are wired in parallel (see
table of connections on page 10) and the ports are fed
out to 5 D-type sockets grouped in ports. These signals
are also available on a 40-way header (J5) for expansion
purposes. Other important signals can be accessed via
the other expansion header J2$ (see table of connections
below). Port E has only 3 connections, which reflect the
pin outs of the various PICmicro devices themselves.
When using an 8-pin or 14-pin device it should be placed
in the upper pins of the 20-pn DIL socket as marked
on the board. Please refer to device datasheets for
availability of port outputs on each device.
NOTE: RA4 on some PICmicro devices has an open
collector output. This means that you will most likely
need a pull up resistor to be able to device an LED etc.
Please see the datasheet on the device you are using for
further details.
WARNING: Only fit one PICmicro device at a
time. Inserting more than one PICmicro device
will cause programming to fail and may even
cause damage to the board or the PICmicros.
4. Reset push button
PB1 provides a reset by pulling the MCLR pin low. Note
that the PPP programming chip will reset the slave
PICmicro as part of the send routine so that you do
not need to press this switch each time you send your
program to the board. If you are using a device with
internal MCLR functionality then you will have to ensure
that the chip os configured with an external MCLR to
allow the reset operation to work. Devices using the
internal MCLR configuration setting will be able to use
the reset switch as a digital input.
5. Frequency selection
The clock signal for this board can be either from the RC
network or by the crystal. SW2 dictates whether an RC
circuit or a crystal circuit is used on the slave PICmicro
device. SW1 dicates whether a fast or slow RC network
is used and in this mode RV1 will allow you t vary the
oscillator speed. By default the board is fitted with a
19.6608MHz crystal. The crystal fits into a small socket,
which allows the crystal to be easily changed. This
frequency was chosen as it divides down by PICmicro
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