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octobar_photo.jpg The OctoBar is a product that allows control of up to eight RGB LED modules, nominally 12V at 100mA per color channel. It is based on eight A6281 3 channel 10-bit PWM LED driver ICs. Each channel has an independent 10-bit PWM, for a total of 24 channels of PWM LED control. The OctoBar is designed to operate with the Satellite S-001 LED module, connected with standard modular telephone cables.


Controller: Allegro A6281 x 8
LED Current: 100mA per channel (preset with resistor)
Current: 2400mA maximum (all channels on)
Power Supply: 6V to 17V DC (depending on LED forward voltage)
Inputs: DI, LI, EI, CI
Outputs: DO, LO, EO, CO, 24 current sinks
PCB Size: 6.40 x 1.97 inches
Header Spacing: 0.1 inches
LED Connector: 6p6c RJ25 (6p4c also works)
Power Connector: Screw terminals, 0.2 inches

Power Connections

External power should be 6V to 17V, input on the + and - screw terminals. If power is connected correctly, the green PWR GOOD LED will light up. When used with the Satellite S-001 LED module, 12V power is ideal. For each Satellite S-001 LED module connected, up to 300mA will be required from the supply. External power is fed directly to the supply pins on the LED output connectors, so the power supply should have a voltage no more than 3 volts higher than the LED forward voltages if custom LED arrays are used.

The OctoBar is polarity-protected; if power is connected backwards, the OctoBar will not be damaged. The PWR GOOD LED will not light during reversed power. However, it still possible to damage the OctoBar or other devices if the data cables are connected incorrectly, as explained below.

Power can be chained from one OctoBar to the next, simplifying power connections. The screw terminals should be used to transfer power in this way, instead of the small 6-pin data cables. Since each subsequent OctoBar adds up to 2400mA to the current running through the first OctoBar in a chain, no more than four OctoBars should be chained before making another parallel connection to the power supply.

On OctoBar V1.1 models, the V+ pin is no longer connected to the V+ supply rail. There is a solder jumper on the bottom of the PCB which will allow reconnecting this pin if desired. This will greatly reduce the risk of accidental damage to the OctoBar. All power should be connected to the screw terminals, which are polarity-protected.

Data Connections

The data INPUT and OUTPUT headers are designed to be hardware compatible with the ShiftBrite connection scheme. This means the OctoBar can be plugged into a ShiftBrite Shield or a Shifty VU Shield. The data protocol is identical to ShiftBrites, ShiftBars, and MegaBrites. In fact, all of these devices can be controlled on the same data chain, assuming the appropriate power supply is connected to each type of device.

Control data cascades from the first A6281 chip to the next, finally appearing on the OUTPUT header. This allows multiple OctoBars to be chained together with six-pin cables to control many LEDs from only four data pins.

To preserve compatibility with other macetech LED modules, the data connector pinout also includes the raw supply voltage. This requires that care is taken when wiring up OctoBar and other compatible modules. By shifting the connector over, it is possible to directly apply the supply voltage to logic level inputs or outputs of any connected device, including the controller device. If an OctoBar is connected in this way, the nearest A6281 chip to the incorrect cable will be destroyed and have to be replaced.

No damage
This kills the OctoBar.
(macetech cable colors may not match diagram)

Rules of thumb when wiring OctoBars: always wire with power OFF, always check your wiring before powering on, always make sure you can see and verify each cable connection is correct

LED Connections

The OctoBar has eight RJ25 jacks for very convenient wiring of Satellite S-001 LED modules using standard telephone cables. The OctoBar jacks and the Satellite S-001 can use the extra two wires in a 6p6c cable to improve current handling capability, but the more common 6p4c cables will also work fine for most applications. 6p6c cables should be used for longer cable runs (25ft+) where voltage drop may be a concern.

The OctoBar and Satellite S-001 are designed to use telephone cables with “standard” or “voice” wiring. This type of wiring has the wire order reversed on one plug if looking at both plugs in the same orientation. However, many stores sell this type of cable as “straight”, while a cable with matching wire order on both ends is sold as “reversed”. Other store flip these designations. The easiest way to be sure is to only purchase cables labeled for “voice” usage, not “data” usage. Fortunately the “voice” type is the most common.

Command Format

When sending data to the OctoBar, it should be treated exactly like eight ShiftBrite, MegaBrite, or ShiftBar modules chained together. All example code is interchangeable. For details on the data format and example code, please refer to this section of the ShiftBrite documentation: ShiftBrite: Command Format


/home/macetec/public_html/docs/data/pages/octobar.txt · Last modified: 2015/05/22 00:52 by macegr