Glolab GL116 Encoder / Decoder
The Glolab GL116 microprocessor based Encoder / Decoder is designed for use with wireless modules, infrared remote controls and other devices that operate with serial input and output data. It can be used as either an encoder or a decoder by simply connecting a pin either high for an encoder or low for a decoder. It can encode or decode sixteen bits of data and twelve address bits (4,096 addresses).
When used as an encoder, one of two Input modes can be selected by connecting a pin either high or low. In one mode the encoding of data can be active high and in another mode the encoding can be active low. When used as a decoder, either momentary or latched data outputs can be selected by connecting a pin either high or low. A momentary valid transmit output indicates when valid data is being received.
When not encoding or decoding, the GL116 remains in a low power mode where it draws only 1 microampere making it ideal for battery powered applications. It is powered by 5 volts and draws about 3.5 milliamperes not including loads, when active. As an encoder it becomes active when triggered by transmit enable or data input. As a decoder it becomes active when it receives serial data.
An internal clock is generated by a 4 MHz ceramic resonator which provides accurate frequency control and therefore better serial data synchronization than the resistor controlled oscillators used in some encoders and decoders. This allows higher speed data transfer without the risk of lost data. A resonator of the type that has three pins and contains internal capacitors to minimize components is recommended for oscillator frequency control. 4 MHz Resonators are available from Digi-Key, ECS p/n X902, Panasonic p/n PX400 and Mouser, ECS p/n 520-ZTT400MG and from Glolab p/n CR4.
The GL-116 can be powered with 5 volts from a battery or other power source.
One GL116 and one CR4 are required for each encoder application. Another GL116 and CR4 are required for each decoder application.
The following schematic shows a basic wireless RF transmitter application circuit with the GL116 used as an encoder. The encoding function is selected by connecting pin 19 to Vdd.
The twelve address pins can be connected to Vss or Vdd through switches or can be hard wired, they cannot be left floating.
Two different input modes are selectable by connecting pin 20 to either Vss or Vdd. The Vss connection causes the transmit enable and all four data in pins to be active low. In this mode a low level must be placed on the transmit enable pin to initiate a transmit sequence and a low level on any or all the data pins will produce a high level on the serial data output that drives an RF module or infrared LED. Transmit enable and data in pins cannot be floating. They are usually driven by logic or other circuits in this mode.
When pin 20 is connected to Vdd the transmit enable and all data in pins become active high. In this mode a high level on the transmit enable and any or all data in pins will initiate a transmit sequence and will produce a high level on the serial output.
The serial output generated at pin 40 when a transmit sequence is initiated consists of four bytes. The first two bytes contain address bits and the second two bytes contain data bits. These four bytes are automatically sent at least three times (one packet) when a transmit sequence is started regardless of how short a time transmit is enabled in either active high or active low mode. Transmission of packets will repeat as long as transmit is enabled. A packet is sent in 30 milliseconds.
The following schematic shows a basic wireless receiver application circuit with the GL116 used as a decoder. The decoding function is selected by connecting pin 19 to Vss.
Latched outputs can be selected by connecting pin 20 to Vss. Momentary outputs are selected by wiring pin 20 to Vdd.
The packets of serial output that are generated by the transmitter encoder and sent to the receiver decoder by wireless, infra red or other means are fed into serial input pin 40 of the decoder. A packet is stored and the address bytes within it are compared with those of the decoder address pin settings. Address and data bytes within a packet are also compared with each other and if at least two of them match then the data is passed to the output pins. Each of the output pins can both source and sink 25 milliamperes.
The data outputs are not momentarily interrupted if the transmitted data pattern is changed while transmitting, as happens with some decoders. This is important when machinery is being controlled and continuous control of some functions must be maintained.
Please read Characteristics of a wireless system for more about data transmission and addressing.
DOWNLOAD a GL116 data manual including application circuits, in PDF format
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