User manual

Page 22
Document No. 80-15151 Issue 6 HEBER LTD
It is possible to run the sound in the following modes:
6.9.1 Single Channel/Single Speaker (Mono) Mode
This is the lowest cost option, using the standard Pluto 5 Board with a single loudspeaker.
The optional SFX Channel 2, U39, is not fitted and only SFX Channel 1, U8, is operational. A single
loudspeaker is connected to LS1 pins (1 & 2) only. Pins 3,4,5 should be left open.
6.9.2 Dual Channel/Dual Speaker (Stereo) Mode
In Stereo Mode, the optional second channel IC U39 is fitted and 2 loudspeakers are used, connected
to LS1 and LS2 pins. Pin 3 is left open. Channel 1 Volume Control will adjust the level of LS1, Channel
2 Volume Control will adjust the level of LS2.
In this mode true stereo sound effects may be reproduced, although the subjective effect heard by the
player will depend upon the placement of the loudspeakers in the cabinet.
6.9.3 Known DMA Problems
The “E” version of the Motorola 68340 mask that is current at the time of this manual being written
(MC68340PV16E, Mask # 2G67F)
exhibits a DMA fault which can cause audible disturbances on a
sound effect.
This disturbance occurs when the memory area being transferred to the SFX Register in the FPGA
includes the hexadecimal address range xxx3 FFxx. (x meaning any hexadecimal digit).
Thus, to avoid this problem occurring, precautions should be taken when linking sound effect modules
Into the final EPROM map. We suggest that, programme and EPROM size permitting, the area from
hex 0000 0000 to 0003 FFFF (256Kbytes) be reserved for the executable portion of the code, with
sound effects commencing at hex address 0004 0000. If the total EPROM size exceeds 1Mbyte, then
no sound effect should include data in the range 0013 FF00 to 0013 FFFF. Similarly, with larger
EPROM maps, regions at 0023 FFxx, 0033 FFxx, etc should also be avoided.
There is NO problem with code execution in these areas, the only difficulty occurs when a Sound DMA
transfer passes through these regions.
We believe that these problems are reduced or eliminated when the Function Code Register (FCR)
in the DMA Module is initialised to value 0xDD.
6.10 Using Multiplexed Lamps
On all Multiplex lamp outputs, the Column Drives, LC0-15, SINK current to ground and the Row
Drives, LR0-15, SOURCE current from the Lamp Supply (+36V or +48V). Thus, any lamps should be
connected between a Row and a Column drive with their series diodes orientated with the cathode
towards the Column Drive.
The choice of operation at 36V or 48V is determined by the Power Supply and the software. When
running at 48V, the software will sequentially drive all 16 Columns, LC0-15, on a 1/16 duty cycle, each
column being ON for 1mS and OFF for 15.
When running at 36V, the software will sequentially drive only the first 8 Columns (LC0-7) on a 1/8
duty cycle, each column being ON for 1mS and OFF for 7.
The Lamp Multiplex Drive Circuitry is designed to drive 12V, 100mA bulbs. However, it is permissible
for a small number (up to 16) of positions to drive either a higher power bulb (12V, 180ma) or a pair of
100mA bulbs. These "high load" positions should be arranged such that no more than one is on any
one Row or Column drive.
6.11 Using Multiplexed LEDs
The multiplexed LED drive circuit is intended to be used with Common Cathode digits, either 7
segment plus decimal point or 14 segment. The common cathode connection of each digit should be