[SOLVED] Wireless circuit problem !!!!

[Jigar 4 Electronics]

I have made a wireless circuit using this circuit **broken link removed** .
I have checked all the connection and voltages. Everything is perfect but still it doesn't work :-( .... I am trying to get data from HT12D (Directly at 10 - 13).

Please tell me is there anything which I should check or may I have missed???
I need the help of your experience.... Please help.....

 

[BradtheRad]

The schematics look fairly simple but there are many places where the flow of electronic information can cease.

In addition to normal circuitry your project includes radio transmitting, radio receiving, and human input.

You need to verify that each stage is working.

* Is the supply voltage within correct range? Is it dropping too severely when the module starts transmitting?

* Is the A-434 (with 4 pins) drawing proper current when it's idle? Does current draw increase when it's transmitting (as would be expected)?

* Is output coming from the HT12E chip? If not, then are your input pins really going low when you press a switch?

* Looks as though pins 15 and 16 are connected to an onboard oscillator. Can you observe a waveform? (Okay, so it may not be possible to make this test.)

* Can you use an RF detector (of whatever sort is handy) to verify that broadcast is coming from the antenna? Field-strength meter? Grid-dip meter? Homemade or otherwise? Buzzing in a high-gain amplifier whose only input is a few inches of wire close to your transmitter? Buzzing in a nearby tv which you set to receive air broadcasts? TRy the tv on different channels.

* Your project transmits on 430 Mhz. This is about twice the frequency of tv channel 13. You might pick up a subharmonic (or something like it) on an old/miniature tv with a variable tuning dial.

* Is proper supply voltage going to the other A434 chip (with 8 pins)?

* Can you verify expected voltage levels at the chip's output pin?

* Is any signal reaching pin 14 (marked 'DIN') of the final IC?

* Baud rates must match. If they don't then you won't get much in the way of output.

* Try a check for internal IC fusing by testing voltages at all pins. Not a good sign if you get midway voltage levels in a digital IC.

* Test for bad solder joints. Visually inspect with a strong magnifier. To test with a meter: With power applied to the circuit. Touch one lead directly to a pin, other lead on the trace leading to it. A bad connection will produce some reading. Don't use an ohmmeter on a setting that will send several mA into your IC which could ruin it.

* Assembling electronics components is often unforgiving of mistakes. When you apply power to a miswired IC, it can be ruined instantly. This is why it's a good idea to use IC sockets, so you can remove the IC's and check continuity of all paths on your circuit board with an ohmmeter.

 

[Jigar 4 Electronics]

How can I solve this problem, which have mentioned by BradtheRad :
* Is output coming from the HT12E chip? If not, then are your input pins really going low when you press a switch?
There are other problems also, but this should be solve first...
Can anyone help ?

 

[kak111]

Have you noticed that TE-pin must be low-state when transmitting.

Functional Description
Operation

The 212 series of encoders begin a 4-word transmission cycle upon receipt of a transmission enable (TE for the HT12E
or D8~D11 for the HT12A, active low). This cycle will repeat itself as long as the transmission enable (TE or D8~D11) is
held low. Once the transmission enable returns high the encoder output completes its final cycle and then stops

**broken link removed**

 

[Jigar 4 Electronics]

How Can I solve this problem :
* Is output coming from the HT12E chip? If not, then are your input pins really going low when you press a switch?

Input pins gets low when I press the switch, but There is no output reaction at the output pin of HT 12E (on 17th Pin). I'd check this on Cathode-Ray Oscilloscope.
Can anyone tell me which kind of change there should be appear in the waveform of 17th Pin of HT 12E when I press the Input pins ??? (Right now I m getting no change in waveform at pin 17 of HT 12E )...

 

[BradtheRad]

1.

I believe you should see a train of pulses come from pin 17 when you're sending.

According to the datasheet, the module continues sending as long as the buttons are pressed.

2.

Are you pressing a variety of buttons to see if you get any results whatsoever?

Notice per post #4 the transmit enable button must be pressed at the same time.

3.

While transmit enable is pressed, see if there's any waveform on the oscillator pins 15 & 16. Just on the chance you'll spot something. (Unless a meter or oscilloscope would load the circuit and stifle oscillations).

4.

Read current draw through power supply lead, both when idle and when you press buttons. Disconnect the A434 transmitter module while you do this test.

Any change will tell you something.

5.

Also read voltage across supply leads, similar to above.