Which functional specifications are most important in an audio interface?

How to interface HT12E with AT89S52?? also give the specifications of the antenna that must be used with TWS43?

• please send the circuit diagram... also give the specifications of the antenna that must be used with TWS-434 and RWS-434....

• Answer:

  The HT12E data sheet is in the first link below. This is a data encoder for 4 channels that works with a data decoder device called the HT12D. This is a data encoder. It generates a serial data word according to the 12 lines labelled address and address or data. The operation is to set the address and data lines for the code, and the output appears as a serial bit stream (12 bit words) at the DOUT pin when the !TE (transmit enable active low) line is brought low for less than one word length. The first 8 bits are designated as addresses so may use fixed code to identify a group or device (switches or links). The last 4 bits are additional data or address lines. How these 12 lines are used is really up to the user application. The preset 8 bit address code must agree with the receiver (if using the HT12D decoder chip). The 4 data bit part could be from a microprocessor, or from 4 push buttons as in a remote control. These are CMOS inputs with pull-ups, so are logic high when nothing is connected or the switch is open, logic low when connected to ground. Page 8 of the data sheet shows a basic setup with the code for the switches in the positions shown. The diodes are only to operate the Transmit enable whenever a data press-button is operated (low). Driving the four data inputs from a microprocessor, there could be 4 digital i/o lines as outputs, with the !TE line from a fifth data i/o output line. The power supply is 5V to match the transmitter unit, but could be up to but not more than 12V if the transmitter is the same. The Atmel microprocessor is in the second data sheet. It seems to have plenty of i/o lines suitable for operating the encoder device. The third link shows that the encoder can be used without a microprocessor, which is why it would be used normally. If you have a microprocessor, it can be programmed to do the encoding by itself. The RF transmitter and receiver units (see fourth link for data sheet) uses the data from the DOUT pin of the encoder to drive the data input of the unit. Note that the data sheet also has application examples, showing how to use them. This data interface will only work properly if the unit is run from 5V power as is the encoder (same voltages). If they use different voltages, some sort of voltage level translation is required between them. The encoder clock should be set to produce < 3Kbit/second, which also has to match the receiver decoding rate. The transmitter is intended to operate with a 50 ohm load. This means the connection from the transmitter to an antenna with 50 ohm impedance at the operating frequency using 50 ohm coaxial cable, no more than a meter or so long to reduce loss. Any antenna that is 50 ohms at a nominal 433.92MHz will work. Apparently a straight wire connected directly to the transmitter ANT output 13 inches long does the trick. Using a wire antenna like this the ground of the transmitter should be connected to the body or metal housing of whatever it is you are making directly (very short connection, less than 1cm).. If you want to send data like readings rather than just 4 buttons remote control, the encoder and decoder are not necessary. Use a microprocessor at each end (transmit and receive). The last link shows how to do that using a basic stamp (microcontroller), which generates a serial data stream to send over the RF connection.