Difference between revisions of "Art Controller Usage"

Revision as of 19:08, 11 September 2012

Timing:

The relay timing of the Art Controller is performed by the internal clock of the on-board microcontroller, and the delay time is configured with the DIP switches. Using the DIP switches, it is possible to select delay periods ranging from 1 second to 31 hours.

The DIP switches have five numeric values (1, 2, 4, 8, and 16 seconds), and three multipliers (×6, ×10, and ×60). The numeric part can be adjusted to add up to any value between 1 s and 31 s, and the multipliers allow these values to be scaled up into the following ranges of nominal delay times:

1 s — 31 s 6 s — 186 s (3 minutes and 6 seconds), in 6 second increments 10 s — 310 s (5 minutes and 10 seconds), in 10 second increments 1 m — 31 m, in 1 minute increments 6 m — 186 m (3 hours and 6 minutes), in 6 minute increments 10 m — 310 m (5 hours and 10 minutes), in 10 minute increments 1 h — 31 h, in 1 hour increments Please note that all delay times are approximate. While delay times specified with the DIP switches are typically quite accurate near room temperature, the exact period does depend on operating temperature and can vary by as much as ±10%, towards the edges of the operating temperature range, -40°C to 85°C.

Unless configured otherwise, the behavior of the Art Controller is such that the relay coil energizes as soon as a trigger is received. It stays energized for one delay period (the length of time set by the DIP switches) and then turns off the coil until the next trigger is received.

Triggering:

The Art Controller can have its cycle triggered by an external button or switch, or by an external input signal.

To use an external button or switch: Connect the two pins of the Art Controller's trigger input to a normally open ("NO") button switch. When the button is pressed or the switch is thrown, it connects the two pins of the trigger input together, triggering the Art Controller.

Instead of hooking up a button, you can hook up any external logic-level signal to the trigger input, for example from a light sensor or motion sensor. The Art Controller will perceive a low-going signal the same as it would a button press.

Configuration options and auxiliary inputs:

Besides the trigger input and the timing DIP switches, there are four additional I/O pins that can be used as auxiliary I/O pins or as configuration jumpers:

Cancel Trigger. A low-going input on this line can be used to revert the Art Controller to the un-triggered (idle) state. If the input is held low (e.g., connected to ground), it will also prevent any new triggers from being accepted. You can use this to add on an "STOP" button, or you can connect it to a switch to temporarily lock-out the trigger button. Trigger @ Reset. You can solder a wire between this pin and ground to configure this option. If configured, the Art Controller will register a trigger (as though you had pressed a trigger button) when it first powers on. Start/Stop on Trigger. You can solder a wire between this pin and ground to configure this option. If configured, the Art Controller will treat a second trigger signal as a "cancel" signal. In other words, if you press a trigger button one time, the Art Controller begins its cycle, but if you press it a second time, it will stop the cycle. (If this option is not configured, additional triggers beyond the first will be ignored so long as a cycle is in progress.) Repeat. You can solder a wire between this pin and ground to configure this option. Normally, when the Art Controller receives a trigger, it energizes the coil for the specified delay time and then goes back to the idle state. When the repeat option is configured, a trigger instead begins a continuous cycle where the coil is alternately energized and off, each for the specified delay period. The cycle can be halted by using the Cancel input, by pressing the trigger again (if Start/Stop on Trigger is configured), or by removing power from the Art Controller.

Mechanical relays and configuration: The relay on the Art Controller is an electromechanical type: A mechanical switch that is flipped by an electromagnet when energized.

The relay is an "SPDT" type, meaning that it can be used either as a normally-open or normally-closed relay. When idle, the "Common" terminal of the output terminal block is connected to the "NC" terminal, and when the coil is energized, the "Common" terminal is instead connected to the "NO" terminal. When power is removed from the coil (or from the Art Controller as a whole), the relay reverts to its idle state.

Thus, depending how you hook it up, it can be used to either turn on or turn off an external load when the coil is energized.

Powering the Art Controller

The Art Controller requires DC power to operate the microcontroller and relay. It features an on-board linear voltage regulator and accepts input power in the range of 7-15 V DC. (A 9 V or 12 V DC power supply will work nicely.) Your power supply should have the capacity to supply up to 125 mA.

If you prefer, it is also possible to instead configure the Art Controller to operate directly from a regulated 5 V DC power supply by omitting the regulator during assembly. (See build instructions for additional details.)

The Art Controller has an on-board two-pin screw-terminal block for connecting to power. You can also add an optional barrel jack (sold separately) for connecting to a plug-in power supply.

Typical power consumption is approximately 95 mA when the coil is energized and 13 mA when idle.

Programming the Art Controller

The Art Controller is an open-source, hackable relay board that can be reprogrammed.

While no programming is required— the microcontroller comes preprogrammed to do everything listed above — the Art Controller's onboard ATtiny2313A microcontroller can be reprogrammed in circuit with an AVR ISP programmer, such as the USBtinyISP, to make either minor or radical changes to its behavior. You can vary the timing, the way timing is used, or do anything else that you care to, with up to 16 available digital I/O lines.

To give you just a few ideas, here are some things that you could reprogram the Art Controller to do:

Use much shorter or longer delays. Wait for a fixed amount of time between being triggered and starting the relay cycle Trigger only when the input signal stays high for a certain amount of time. Trigger automatically when a certain amount of time passes without otherwise being triggered. Trigger only when a set of digital inputs (up to 13 digital inputs) meet a specific set of high and low conditions. Control the time delay with the digital inputs. Trigger at (pseudo) random intervals. Operate as a repeating timer, with different duty cycles. Activate for a (pseudo) random amount of time. Work as a "pulse" driver, only turning on the relay when the input is high. Output a clock or sync signal, even when the module isn't triggered. Output a sync signal with the same or opposite sign of the relay state. Turn on a warning LED or siren a few moments or minutes before turning on the relay.

Contact ratings and safety

While the relay contacts are rated for AC loads of as high as 120 V (or higher, under some circumstances), we have labeled the Art Controller for loads of up to 40 V AC. Do not exceed this value without providing an external housing that protects fingers and foreign objects from exposure to that voltage. If you choose to exceed our rating (at your own risk), be certain that you have thoroughly addressed the safety issues and taken any additional measures as necessary to ensure that the board can be operated safely. At a minimum, your external enclosure should prevent unintended access to the relay terminals and the underside of the board.

The relay shield is labeled with a current rating of 5 A. However, as per the relay's datasheet, it can be safely operated as high as 10 A (AC or DC) if configured strictly as an N.O. (normally open) relay, with nothing connected to the N.C. terminal.

Please refer to the relay's data sheet (PDF) for additional specifications.