Ahh using logic gates like flip flops and OR gates. Why cant you design a wireless circuit that transmits an 16 bit pulse to a receiver that decodes this and kills the engine.
The IR LED will put out a continuous IR signal when it's turned on and the IR Photodiode will produce a signal when it sees an IR signal, but this sort of "continuous wave" signalling is very unreliable, particularly outdoors, but is bad even in standard room lighting. Normally the IR LED signal is modulated, usually around 38KHz, and a modulated IR detector is used to receive it, not a plain photodiode. The "IR Remote for the BoeBot Robot" tutorial goes into detail on how to use one of these IR detectors. Parallax sells them and they're available through many other dealers. There's also a circuit given in the back of the tutorial on how to generate a 38KHz signal using a 555 timer and an IR LED. This circuit can be triggered by a Stamp or by a Holtek encoder. The IR detector can also be attached to a Stamp or to a Holtek decoder. Have a look at the tutorial.
OK, that mean connecting directly IR to the HT 12 encoder will not work, without carrier freq.
Directly connecting the IR LED to the encoder won't work very well mostly because the encoder can only handle output currents of a few milliAmperes, maybe 3mA max. (look at the datasheet). High output LEDs will produce some light at 3mA, but not a lot. You need to be able to provide about 20mA for full brightness. You can do this with a switching transistor. The 555 timer has a high current output and can easily provide 20mA or more.
Directly connecting the IR LED to the encoder won't work very well mostly because the encoder can only handle output currents of a few milliAmperes, maybe 3mA max. (look at the datasheet). High output LEDs will produce some light at 3mA, but not a lot. You need to be able to provide about 20mA for full brightness. You can do this with a switching transistor. The 555 timer has a high current output and can easily provide 20mA or more.
Please, post the simple schematic of HT 12e/d with ir link.......
as the current is low we can increase it by transistor then what the use of 555 timer chip??
The 555 timer is there to provide the 38KHz modulated IR and it happens to have enough drive capability for full brightness of one or more LEDs.
Please read the tutorial that I mentioned earlier. The circuits shown in the tutorial are for connecting to a Stamp, but you can connect them to the Holtek encoder's output the same way.
The 555 timer is there to provide the 38KHz modulated IR and it happens to have enough drive capability for full brightness of one or more LEDs.
Please read the tutorial that I mentioned earlier. The circuits shown in the tutorial are for connecting to a Stamp, but you can connect them to the Holtek encoder's output the same way.
Hello sir,
I have seen this Tutorial ( IR Remote for the Boe-Bot robot (v1.1)),
but i am confused pls. post the schematic of this circuit........
Today i buy a Rx & Tx from local market, the freq. is of 433Mhz (not sure) now pls give direction with Holtek 12E/D...
Buy your products from Parallax and perhaps someone will help. Otherwise please ask these questions in the forums supported by the products you do buy.
Just as a general statement along the lines of what Franklin mentioned. This is a Parallax support forum intended primarily for support of Parallax products and products sold by Parallax in their webstore. This specific forum (General Discussion) is for a variety of topics, not all directly related to Parallax products. We (the participants in this forum, most of whom are volunteers, not Parallax employees) are often willing and sometimes eager to discuss other stuff and help with questions not related to Parallax products. There are limits though. I think most "helpers" lose interest when their advice isn't taken or when they ask questions that the questioner doesn't answer for whatever reason. It is also against forum rules to "bump" a thread with a message with no other content. So ...
1) Feel free to ask questions
2) No one here is under any obligation to answer them, so, the more interesting you make your question, the more likely you are to get someone to help out.
3) Follow the advice given. If you don't like the advice or you want to do something different, don't be surprised if you lose interest from those who have offered it. At least mention what you plan to do and why. You can also start a discussion about your reasons. That may rekindle interest. No guarantees.
4) If you're asked to supply information, do it. You can commonly find almost anything via a simple websearch. If you don't do it, someone else will have to and they're already volunteering their time. You'll also learn how to do it. If you ask how because you really don't know where to start, someone will give you suggestions to start, but you have to do the work.
5) Demonstrate that you're willing to put some effort in rather than just asking questions ("give me", "tell me", "show me"). You'll learn more and keep people's interest.
Generally, you'll get a lot of very expert help. Be patient, Be respectful. Work hard. Enjoy.
I have buy RX & TX in my local market, i can't effort abroad product.........................
I am sorry to ask so many question!!
Let start with beginning, i am making this wireless switch for my robotic car in this there will be 4 gear motor operated by this holtek decoder (right,left, forward, reverse...)
i have assembled the circuit in my breadboard, it seem to not working i have taken 5V power supply , the encoder osc. have 950Kohms(=1Mohms) variable resistance & in decoder it is of 50Kohms variable resistance.........
In encoder & decoder all add. pins are left open and the transmission enable is set to low active the data pins one of them is kept low directly to GND ( no Diode Used), & Dout is given to TX
in decoder part the Valid transmission is set to High active with V cc directly....
and all add. are left open the Data pins are connected to led's ....
Now i want to know first how to check whether the RX & tx is working without HT 12e/d............
You forgot to put the schematic in your post RITESH KAKKAR...
Is there any more information on your scrolling LED display? I can't seem to find any info on your website... I am interested, and want to learn more.
Also, What is HACKDISHTV?
I am testing my TX & Rx module by:-
connecting the data in to Tx by gnd & vcc without sq. wave!!
connecting 2 LED from GND & Vcc to data output of Rx there are no changes i have seen both led were glowing....on touching the tX data pin to GND & Vcc there are no changes...!!
and after adding 56 ohms resistance in series led does not glow
Now i am checking my Tx & Rx by connecting led across data of Rx with and without 56Ohms resistance.....without res. the led glows & with resistance in series it does not glow.
when i put the data in of tx with GND & vcc no changes were seen in the output of Rx, why ??
I notice you have the LED's on Dout pins of the 12D directly connected. The datasheet says those pins can only sink/source 1.6mA. You would need 2.7K resistors in series with your LED's. Unless they are high brighteness LED's you may not be able to see them light up.
You really should use a buffer with more current drive between the 12D and the LED's.
Hmm... I noticed that in the diagram, is some wireless serial to parallel converter, and then to the microcontroller?
I had built wireless circuits on that before, but without the converter. Instead, the pins of the receiver is connected to the serial port pins in the microcontroller, and the transmitter, in the other microcontroller, to the serial port too.
Now i am not connecting led directly to the Rx module i have connected BC 547 npn transistor switching the LED when the Data in of Tx is in HIgh Z (i.e. open), the led blink (on/off) when i connect the data in of tx to vcc & gnd led glow continuously, 300ohms resistance is connected in series.. with the output of transistor to led!!
I want to know why led is glowing on/off when no data is input??
Do not post any more messages that just ask for help. If anyone is interested in helping you, they will do so. As I've mentioned before, it helps if you follow the advice that's given and it helps if you provide information, like updated schematics, which would be useful to someone who might be willing to help. Your descriptions are incomplete and confusing, certainly to me, and you are asking for a lot of help on a topic that has little to do with the purpose of these forums.
Then pls pls tell what to do, i don't have oscilloscope.........
First, you need to provide a better schematic. I have used paint for block diagrams and simple schematics so I know it is not so hard to do.
Then you need to describe the problem you are having while referring to the schematic. I suggest using small numbered boxes to refer to specific points on your schematic.
Now i am not connecting led directly to the Rx module i have connected BC 547 npn transistor switching the LED when the Data in of Tx is in HIgh Z (i.e. open), the led blink (on/off) when i connect the data in of tx to vcc & gnd led glow continuously, 300ohms resistance is connected in series.. with the output of transistor to led!!
I want to know why led is glowing on/off when no data is input??
I am testing this tx & rx by this, as i don't have oscilloscope........any method for checking it.
Would it be simple if you have two similar microcontrollers, with serial capabilities, and then one microcontroller to send and one microcontroller to receive data.
Then if the receiving side is getting the correct, required data, then connect each microcontroller with the transmitter, and another one with the receiver.
On many times the serial->parallel decoder aren't required, unless if you are using older 8051 or PIC microcontrollers.
Comments
I will do it, this is not the right time!!
OK, that mean connecting directly IR to the HT 12 encoder will not work, without carrier freq.
i am right?? but why data sheet shows that??
Please, post the simple schematic of HT 12e/d with ir link.......
as the current is low we can increase it by transistor then what the use of 555 timer chip??
Please read the tutorial that I mentioned earlier. The circuits shown in the tutorial are for connecting to a Stamp, but you can connect them to the Holtek encoder's output the same way.
Hello sir,
I have seen this Tutorial ( IR Remote for the Boe-Bot robot (v1.1)),
but i am confused pls. post the schematic of this circuit........
Today i buy a Rx & Tx from local market, the freq. is of 433Mhz (not sure) now pls give direction with Holtek 12E/D...
1) Feel free to ask questions
2) No one here is under any obligation to answer them, so, the more interesting you make your question, the more likely you are to get someone to help out.
3) Follow the advice given. If you don't like the advice or you want to do something different, don't be surprised if you lose interest from those who have offered it. At least mention what you plan to do and why. You can also start a discussion about your reasons. That may rekindle interest. No guarantees.
4) If you're asked to supply information, do it. You can commonly find almost anything via a simple websearch. If you don't do it, someone else will have to and they're already volunteering their time. You'll also learn how to do it. If you ask how because you really don't know where to start, someone will give you suggestions to start, but you have to do the work.
5) Demonstrate that you're willing to put some effort in rather than just asking questions ("give me", "tell me", "show me"). You'll learn more and keep people's interest.
Generally, you'll get a lot of very expert help. Be patient, Be respectful. Work hard. Enjoy.
Cheers,
Peter (pjv)
I have buy RX & TX in my local market, i can't effort abroad product.........................
I am sorry to ask so many question!!
Let start with beginning, i am making this wireless switch for my robotic car in this there will be 4 gear motor operated by this holtek decoder (right,left, forward, reverse...)
i have assembled the circuit in my breadboard, it seem to not working i have taken 5V power supply , the encoder osc. have 950Kohms(=1Mohms) variable resistance & in decoder it is of 50Kohms variable resistance.........
In encoder & decoder all add. pins are left open and the transmission enable is set to low active the data pins one of them is kept low directly to GND ( no Diode Used), & Dout is given to TX
in decoder part the Valid transmission is set to High active with V cc directly....
and all add. are left open the Data pins are connected to led's ....
Now i want to know first how to check whether the RX & tx is working without HT 12e/d............
Thanks..!!
Please post schematics of what you have built on your breadboard.
C.W.
here is the schematic.............................
Is there any more information on your scrolling LED display? I can't seem to find any info on your website... I am interested, and want to learn more.
Also, What is HACKDISHTV?
-Tommy
I have posted schematic above, sorry it is not so good but i have drawn in paint................
It's ok to leave all those pins floating?
connecting the data in to Tx by gnd & vcc without sq. wave!!
connecting 2 LED from GND & Vcc to data output of Rx there are no changes i have seen both led were glowing....on touching the tX data pin to GND & Vcc there are no changes...!!
and after adding 56 ohms resistance in series led does not glow
Now i am checking my Tx & Rx by connecting led across data of Rx with and without 56Ohms resistance.....without res. the led glows & with resistance in series it does not glow.
when i put the data in of tx with GND & vcc no changes were seen in the output of Rx, why ??
I notice you have the LED's on Dout pins of the 12D directly connected. The datasheet says those pins can only sink/source 1.6mA. You would need 2.7K resistors in series with your LED's. Unless they are high brighteness LED's you may not be able to see them light up.
You really should use a buffer with more current drive between the 12D and the LED's.
C.W.
I had built wireless circuits on that before, but without the converter. Instead, the pins of the receiver is connected to the serial port pins in the microcontroller, and the transmitter, in the other microcontroller, to the serial port too.
Now i am not connecting led directly to the Rx module i have connected BC 547 npn transistor switching the LED when the Data in of Tx is in HIgh Z (i.e. open), the led blink (on/off) when i connect the data in of tx to vcc & gnd led glow continuously, 300ohms resistance is connected in series.. with the output of transistor to led!!
I want to know why led is glowing on/off when no data is input??
First, you need to provide a better schematic. I have used paint for block diagrams and simple schematics so I know it is not so hard to do.
Then you need to describe the problem you are having while referring to the schematic. I suggest using small numbered boxes to refer to specific points on your schematic.
I am testing this tx & rx by this, as i don't have oscilloscope........any method for checking it.
Then if the receiving side is getting the correct, required data, then connect each microcontroller with the transmitter, and another one with the receiver.
On many times the serial->parallel decoder aren't required, unless if you are using older 8051 or PIC microcontrollers.
You don't need an oscilloscope for all that.