AU335 Hardware Interfaces

This section describes the characteristics and operation of all connectors on the AU335.

Power Connector

The power connector for the AU335 is rated for 12V@3A. The plug is a right-side positive, locking 2-pin (1x2) connector.

USB C Port

The AU335 has a USB 2.0 Type-C port, which is capable of transfer speeds up to 480 Mbit/s. The USB connector can supply up to 1A of power for peripherals.

The USB also operates in host mode to update firmware on connected devices.

Audio Output

The AU335 has one 3.5mm stereo mini jack for stereo audio output which delivers 1.6 volts peak to peak.

The audio connector has the following pinout:

Conductor	Signal

Conductor	Signal
Tip	Left Channel
Ring	Right Channel
Sleeve	Audio Ground

GPIO Block

The AU335 has a 12-pin Phoenix GPIO port with 8 bi-directional GPIOs.

The GPIO port is a standard design manufactured by Phoenix Contact, Wurth Electronics, and others. Pluggable GPIO terminal blocks can be inserted into the GPIO connector to make bare-wire contacts (see this page for an example part). These terminal blocks can be purchased from the BrightSign Store. If you wish to source your own terminal blocks, make sure to use 4-pin or 6-pin blocks (12-pin blocks are extremely difficult to remove from the GPIO port).

Connect the LED outputs to the LED ANODE and connect the LED CATHODE to the ground. If you want to connect another device, then the output is capable of sourcing or sinking up to 3.3V at 24mA, but there is a series resistor of 100Ω in each line.

The GPIO also allows for connecting of external contact closures to the ground. In order to connect a switch, connect one side of the switch to the switch input, and connect the other side to one of the ground pins on the GPIO connector. The connector can also supply 3.3V at up to 500mA to an external device. The 3.3V output is polyfuse-protected and can source up to 500mA.

If one BrightSign player is driving the inputs on another BrightSign player, then you can drive at most three inputs from one output. The following calculations explain this limitation:

Note

The GPIO outputs have 100Ω series resistors; the GPIO inputs have 1K pullup resistors to 3.3V; and the input threshold is 2V high and .8V low. The high voltage is not problematic, but the low voltage can be if there are too many inputs connected to one output.

1 out driving 1 in	V=3.3*100/(100+1,000)=0.3
1 out driving 2 in	V=3.3*100/(100+500)=0.55
1 out driving 3 in	V=3.3*100/(100+333.3)=0.76
1 out driving 4 in	V=3.3*100/(100+250)=.94 (This is too high, so 1 output driving 3 inputs is the maximum)

The following table describes the pinout of the GPIO on the AU335:

Pin	Function	Pin	Function

Pin	Function	Pin	Function
1	GND	7	GND
2	3.3V	8	3.3V
3	BUTTON 0	9	BUTTON 4
4	BUTTON 1	10	BUTTON 5
5	BUTTON 2	11	BUTTON 6
6	BUTTON 3	12	BUTTON 7

The following schematic illustrates the pinout of the GPIO connector:

Ethernet Port

The AU335 has a connector for 100baseT networking. The maximum length for Cat 5E cable is 100 meters; the allowed length can be higher or lower depending on the quality of the cable.

HDMI ARC/eARC

The AU335 has one standard micro-HDMI^® connector. Compressed or PCM audio can be routed over HDMI using ARC and eARC (Audio Return Channel and Enhanced Audio Return Channel). The ARC standard supports high-quality audio over an HDMI 2.1 connection (about 1Mb/second), and eARC supports a higher maximum audio bandwidth (37Mb/second), which allows users to send higher-quality audio.

The AU335 supports multichannel WAV files over the eARC interface, but not over the ARC interface. Sync is supported but Enhanced Sync is not, so users have to send a separate UDP trigger from a synchronized video wall to start audio on an AU335.

The HDMI Type D mini connector (ARC/eARC) delivers a standard 5V.

The HDMI eARC/ARC connection can also be used with CEC to send and receive commands.