TR808-M MIDI Interface for Roland TR-808
M odel 8-4 48 ver. 3 .3 0
5
Copyright © 2015 CHD Elektroservis. All rights reserved.
No part of this publication may be reproduced in any form without the written permission of CHD Elektroservis.
3.2. OPERATION MODES INDICATION
In all working modes (DIN-SYNC IN/OUT and M IDI), the functionality of all
original LEDs on TR-808’s panel remains the same as on the original non-
retrofitted instrument.
LED installed under the START / STOP button indicates MIDI operation
mode. The LED lights continuously while MIDI operation mode is active and the
interface works normally. The LED can indicate received MIDI commands too in
dependence on “MIDI Msg Indicator” global parameter setting – see chapter 3.3.3. If the function is
enabled, the LED always shortly blinks if acceptable MIDI command is received. But in the case of
dense data flow, short blinks are merged and the LED doesn’t light at all apparently. So the indication
of received MIDI commands is disabled during factory setting.
Brightness of indication LED can be adjusted with help of “LED Brightness” global parameter –
see chapter 3.3.5. During factory setting, brightness of the LED is set to maximum.
3.3. GLOBAL PARAMETERS
After TR-808 is turned on (after the interface reset), the interface reads setting of global
parameters from its internal memory. The parameters then control interface’s function during
operation. Values of global parameters are programmable by user – changes can be done with help of
MIDI System Exclusive Messages.
Table 1 – Range of valid values and “Factory Reset“ global parameters values
Value range „Factory Reset“ values
Parameter name
[dec] [hex] [dec] [hex] Meaning
MIDI Channel 0 ~ 15 00 ~ 0F 9 09 MIDI Cannel Nr. 10
Default Program 0 ~ 127 00 ~ 7F 0 00 Pgm Nr. 1
MIDI Msg Indicator 0 ~ 1 00 ~ 01 0 00 Indicator off
DAC Calibration 0 ~ 127 00 ~ 7F 127 7F Max amplitude
LED Brightness 0 ~ 63 00 ~ 3F 63 3F Max brightness
3.3.1. “MIDI CHANNEL“ PARAMETER
The parameter selects MIDI channel number for MIDI data receiving if TR-808 is working in MIDI
mode. MIDI channel Nr. 10 is programmed for MIDI communication during factory setting.
If necessary, MIDI channel number can be changed to any other (1 to 16) by user. The change
can be processed with help of MIDI SysEx message.
3.3.2. “DEFAULT PROGRAM NR.“ PARAMETER
The parameter specifies number of program what will be set as active after TR-808 is turned on
(after the interface reset).
Program Nr. 1 (also see table 3) is set as default during factory setting. If necessary, default
program number can be changed by user. The change can be processed with help of MIDI SysEx
message.
3.3.3. “MIDI MSG INDICATOR“ PARAMETER
The parameter enables or disables indication of received MIDI data in MIDI operation mode (by
LED installed under the START / STOP button).
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