Developing Theatrical Lighting Control with Arduino
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Developing Theatrical Lighting Control with Arduino Heather Heimbach Adam Klein [email protected] [email protected] Alex Lin Michelle Lu [email protected] [email protected] Vivian Zhuang [email protected] Abstract technology, many issues continue to persist in the design and practical application of Ever since the 17th century, stage lighting consoles. Currently, the most lighting has proved to be an essential part of common lighting control consoles are large theatrical productions. However, small or enough in size to limit their portability and startup theatres may have difficulty cause significant inconvenience for the user. procuring quality lighting control, due to the In addition, the cost inefficiency of lighting tendency of professional control consoles to control consoles is a valid concern for many be extremely expensive and superfluous.1 In small theatre companies. Professional order to reduce the cost of stage lighting, lighting consoles readily sell for thousands and provide a simpler alternative to more of dollars, which may not be within the complex standard lighting consoles, theaters realistic budget for small businesses and should utilize Arduinos to control stage productions. In such situations, an Arduino lights. The Arduino is a cheaper and simpler could be used as an alternative lighting open-source microcontroller that can be control console for smaller productions. This programmed to communicate with other study was conducted to analyze the objects in the physical world, such as advantages and limitations of Arduino, and theatrical lights.2 This project explores the how these affect its possible place in the wide array of lighting techniques that can be theatrical lighting industry. created by Arduino and investigates whether it is feasible to use Arduino as an 2. Background economical alternative to standard lighting consoles in the future. 2.1 Theatrical Lighting 1. Introduction In stage productions, lighting performs the essential tasks of providing As technology advances at an visibility of the stage to the audience and exponential rate, options for lighting control enhancing the dramatic elements of the also become increasingly diverse and performance. The ancient Greeks addressed accessible. Proper lighting control promotes these needs by building open-air an efficient use of stage lights, and amphitheaters that allowed them to use facilitates the control of complex lighting natural sunlight to highlight their systems consisting of a larger number of enactments. Theatres were constructed to lights. Despite the advancement in face from east to west, allowing daylight to strike the performers but not those seated in 1 the orchestra. To alter the natural lighting, lights on or off. Additionally, directors could awnings of various hues were placed over now dim the lights to adjust their intensity, the orchestra. These awnings allowed for the opening up the possibility of generating orchestra to be illuminated by colorful numerous dramatic effects.4 waves of transmitted light, creating a Although most theatres adopted gas visually pleasing lighting effect. lighting systems during the first half of the These primitive forms of theatrical 19th century, these systems were rapidly lighting persisted for centuries before stage changed with the advent of electricity. In productions began to utilize the candle as a 1881, the Savoy Theatre in London installed fixed light source in indoor theatres.3 The the first electric theatrical lighting system. earliest records of candlelit theatrical With electricity, technicians maintained the productions stem from Italy, beginning ability to control lights from a distance with around the close of the 16th century. Candles increased safety and less heat than that were mounted on chandeliers above the produced by typical gas systems. By the stage and set, footlights were arranged along early 20th century, theatres almost the front edge of the stage, and ladders with exclusively utilized electric lighting.1 attached candles were positioned between In modern theatre, lighting the wings of the theatre. Collectively, these technicians coordinate effects through mechanisms focused the theatre’s light on computers known as control consoles. The the actors, thus coaxing the audience to common control console has a number of become more immersed in the production functions preprogrammed into the system. rather than their surroundings. These functions allow the lighting Since then, stage lighting technology technician to achieve effects such as light has progressed further, partly due to dimming and color changing. The console significant developments in internal lighting. centralizes control of the lighting and In the 1780s, the candle began to become communicates with the other hardware obsolete with the advent of the oil lamp. The connected in the lighting system through an lamp was utilized in a similar way to the electronic control protocol. A slave device candle, often taking the place of candles in receives the master controller’s commands chandeliers and footlights to become the through the lighting control protocol. In the primary light source for theatrical modern theatre industry, most hardware uses productions.1 the DMX-512 protocol to communicate with The next major development in the control console.5 theatrical lighting was spurred by the creation of gas lighting systems, which first 2.2 DMX-512 Protocol appeared at the Chestnut Tree Theatre in Philadelphia in 1816. Through the DMX-512 is a standard protocol combustion of fuels, gas lighting produced used to set up lighting systems that are artificial light that revolutionized theatrical capable of transmitting commands from a lighting. Gas lighting, unlike the previous master controller to theatrical lighting candles of lamp lighting, could be controlled fixtures. Such lighting control protocols from a distant “gas table,” which contained standardize the method by which systems various knobs. These knobs regulated the are connected, allowing for a wider flow of gas through various pipes connected compatibility between lights and controllers. to light fixtures. The gas table allowed A DMX-512 signal consists of 512 lighting directors the ability to quickly turn channels that are repeated at a rate of 44 2 hertz. Multiple devices can be connected in digital low sets the voltage to -2.5V, a sequence circuit by daisy chaining one whereas a digital high sets the voltage of the device to the next, and each of the devices pin to +2.5 V.7 It is essential for bits to connected to the circuit corresponds to one communicate the correct value, or the DMX of the 512 DMX channels. Signals sent from byte, which contains a sequence of bits, the controller to the devices are referred to would be rendered unable to perform its as DMX output, whereas signals received by function of communicating data to the light. a fixture are referred to as DMX input.6 All data in DMX protocol is sent in a stream Although an Arduino cannot send DMX working at a rate of 250,000 Hz.8 The length output or receive DMX input itself, a DMX- of time required for a bit to be sent is about shield can be attached to the top of the 4 microseconds as seen in Figure 1.7 Arduino. With the shield attached, the DMX bytes are composed of 11 bits. Arduino can be connected to hardware such Bytes are, similar to bits, low capacity as theatrical lights and programmed to digital storage units. Each of the eleven bits communicate signals compatible with DMX composing one byte is assigned a specific lighting systems. role essential to communicating the DMX signal correctly from the DMX shield to the 2.2.1 How DMX Protocol Works light. The order of each bit sent determines the role of the bit in the DMX protocol. For DMX signals are communicated instance, as seen in Figure 1, a start bit through bits, which are low capacity digital containing a value of 0 in binary is sent at storage units capable of communicating only the outset of a DMX byte. Once the start bit two values, either a 1 or a 0, following the has been sent, a grouping of 8 bits is sent binary system. In DMX Protocol, a value of out, which collectively act as storage for a 0 indicates a digital low (LO), while a value value from 0 to 255. This value is of 1 would indicate a digital high (HI).7,8 commonly termed the Channel Value, and is The digital low and digital high settings used to indicate the intensity of an control the voltage of a specific pin. A individual channel. Figure 1. DMX512 Byte Sequence Timing8 3 In systems where the Arduino acts as beginners as well as experienced the master controller, the intensity can be programmers can use to develop software.2 programmed in methods such as DmxSim- ple.write(channel, brightness). The bright- 2.3.1 Arduino Uno ness value will be communicated from the code in the Arduino to the DMX shield, and The Arduino Uno functions with a will then be translated into the proper volt- cable that connects to the standard USB port age signals to be interpreted by the DMX of a computer. The cable connection allows light. users to easily upload programs coded in the Once the 8 bit sequence has been Arduino environment onto the physical sent out, another bit called the Stop bit will board. The microprocessor is equipped with be released. This bit is consistently set on fourteen digital input and output pins, as HI, meaning it holds a value of 1 in binary. well as six analog pins that can be connected Following the Stop bit is the final bit, with wires to create circuits, and various termed the Release Bit, which also contains shields and sensors. It has a ceramic a value of 1. Just as the Start bit signaled the resonator, a power jack, a reset button, and beginning of the byte, the Stop Bit and an ICSP header.11 Release bit indicate the end of the byte sequence.7 2.3.2 DMX-Shields Due to DMX-512 allowing access to a total of 512 channels, to send a signal to A DMX-Shield is a component of a each of these channels, 512 bytes is system using Arduino and DMX Protocol.