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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 'mLoader' .
1. Power supply
The board is normally operated from a regulated DC
supply of 7.5 - 9V 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
7.5V power supply the jumper should be positioned to
the right hand side of the jumper system labeled 'PSU' . If
using USB power place the jumper on the left hand side
of the jumper system. LED D6 indicates that power is
correctly supplied to the board.
Please note that both USB and the PSU cables should
be removed for the Multiprogammer board BEFORE
changing the position of this jumper.
Remember that other E-blocks will have to receive their
voltage by placing a connecting wire from the "+V" screw
terminal of the Multiprogrammer to the "+V" screw
terminal of each E-Block that requires a voltage.
WARNING: Take extra care when wiring in a
power supply 12V may cause the board to run
hot.
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 operating voltage up to the 9-12V
programming voltage. This circuitry routes 0V, VDD and
VPP to appropriate pins on the slave PICmicro devices as
and when necessary.
3. DIL sockets and I/O ports
The slave PICmicro DIL sockets are wired in parallel (see
table of connections below) and the ports are fed out to
5 D-type sockets grouped in ports. These signals are also
6
available on a 40-way header (J5) for expansion purposes.
Other important signals can be accessed via the other
expansion header J24 (see table of connections below).
Port E has only 3 connections, which reflects 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-pin 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 drive an LED etc.
Please see the datasheet on the device you are using
for further details. (Does not apply to 16F1937 device
supplied with the board).
WARNING: Only fit one PICmicro device at a time.
Inserting more then 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 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
is 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
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. For older Matrix TSL courses
a 3.2768MHz crystal is recommended. These frequencies
are chosen as they divide down by PICmicro prescalers
to give suitable frequencies for clock systems and for
facilitating serial communication using standard baud
rates.
The Jumper link system J18, J19 allows PICmicro devices
with internal oscillators to route the signals from the
oscillator pins through to Port A pins 6 and 7. This allows
the devices with internal oscillators to use all 8-bits of
the Port A for I/O operation.
Copyright © 2014 Matrix Technology Solutions Ltd
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