JPM MPS2, Руководство пользователя

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20
Reel Drive Circuitry
Control of four 1.8 degree stepper motors is accomplished by the use of a pre-programmed single chip processor
TMS7041 IC14. More detailed information on this device may be found by consuiting the TMS7041 Data
Manual from Texas Instruments.
Internally the 7041 consists of an eight bit processor, with 4K bytes of ROM and 128 bytes of RAM. Externally
in this application, the device consists of one serial channel, used for communication to the main processor,
sixteen output ports, used to drive the motor phases, and six input lines, used to interface the four reel optos and
two peripheral address lines.
The four reel optos are interfaced via port A- A0 to A3, pins 6 to 9, and are TTL compatible. Since the 7041
communicates on a single serial channel, the device is programmed to recognise a specific address code
identifying it as being addressed. This code is set up on Port A - A4 and A7, IC14 pin 10 and 11, which allows
for up to four peripherals to be interfaced on to the serial bus.
The phase outputs are generated on Ports C and D - C0 to C7, and D0 to D7 of IC14. These outputs drive two
octal darlington arrays IC7 and IC8 whose collectors are connected to the motor phases. Diodes D1 to D16
IN4148, prevent the collectors of the transistors from going negative, whereas D17 and D18 ensure the collectors
are clamped to 48v maximum.
Unlike system 80, the collectors are allowed to rise above the reel voltage (Vreel) by an amount defined by the
zener diodes D17 and D18. This ensures that there is sufficient energy in the system to allow the reels to run at
typically 100 r.p.m. A value of 24v for the two zeners is sufficiently high enough to ensure that most of the
available energy is transmitted to the phase windings, but is low enough to limit the maximum allowed collector
voltage.
Since the 7041 has an on board oscillator, the only components required to generate the system clock are a 5Mhz
crystal XTAL2 and two 27pf capacitors C28 and C29.
All connections to and from the reel drive circuitry are via a 50 way double row header HD2. Pins 14, 15, 34 and
35 are the sources for the reel optos (via 180R resistors R21 to 23) and pins 39, 30, 10 and 19 are the inputs from
the reel optos, which are read via A - A0 to A3, pins 6 to 9 of IC14.
Pins 1, 2 and 4 are three sink lines paralleled from the multiplex circuitry and pin 47, 48,49 and 50 are four
source lines from the same circuitry. These are used when reel illumination is required and allows for up to three
lamps on four reels. Pin 41, reel int, is used to detect the removal of the reel plug, or when using a modular reel
mechanism, the removal of a single reel station. When this link is broken, IC15 pin 19 will go high, which due to
the inversion of the ULA1 , will generate a low level on the interrupt input to the 7041, IC14 pin 13. Detection of
this occurence will generate a code to be communicated to the main processor via the serial link, where
appropriate action may take place (e.g. alarm generation, freeling of game, etc.).