L293d motor driver ic

i have my receiver and transmitter done.. im doing a sort of universal controller. my transmitter consist of 4 by 4 keypad, RTFQ1 RF 330 transmitter module and HT12E encoder ic, my receiver- RRFQ1 RF330 receiver module and HT12D. so now i need to get the signal from my receiver to my motor driver circuit which consist of L293D ic. my teacher is asking me to built a control circuit using 2 to 4 decoder(74VHC139) to decode the data from my receiver to enable my motor to turn clockwise, counter clockwise and stop. i need to use the 3rd column and the 2 middle key of my keypad to control clockwise and counter-clockwise. which is 1001. from the decoder datasheet.. so i dont know how can i give 5v and 0v to 2 of my inputs of L293d without using a switch.. is there a way where it can be done?

HT12D outputs give 0V and 5V to inputs of 74VHC139, then outputs of 74VHC139 give 0V and 5V to inputs of L293D.

godfreyl said:

HT12D outputs give 0V and 5V to inputs of 74VHC139, then outputs of 74VHC139 give 0V and 5V to inputs of L293D.

Click to expand...

erm can u elaborate i dont really get it..

The way I understand your description, the output pins of the HT12D are connected to the input pins of the 74VHC139, and the output pins of the 74VHC139 are connected to the input pins of the L293D.

Maybe I don't understand your problem or question.

but the output pins of the HT12D are suppose to control 4 appliances, so if i take 2 output pin i could only control 2 appliance.. i need to control the motor, clockwise, counter clockwise.. ultimately to move a sliding door.. my L293D motor circuit is done and tested just that the input pins need to be controlled by my transmitter 4x4 keypad which is at the 3rd row, 2nd and 3rd column

benlim90 said:

but the output pins of the HT12D are suppose to control 4 appliances, so if i take 2 output pin i could only control 2 appliance.

Click to expand...

Yes, but you only have one appliance - the motor.

I think it should work like this:

• While one button is pressed, the motor turns clockwise.
• While the other button is pressed, the motor turns counterclockwise.
• When no buttons are pressed, the motor is stopped.
• If both buttons are pressed, the motor is also stopped.

So only two buttons of the keypad are connected to the HT12E encoder, and only two outputs from the HT12D decoder can be used - One output signals when one button is pushed and the other button signals when the other button is pushed.

These two outputs from the HT12D are connected to the inputs of the 74VHC139. The 74VHC139 converts two inputs to four outputs. The outputs from the 74VHC139 will be like this:

• Output a is high when no button is pushed.
• Output b is high when both buttons are pushed.
• Output c is high when only the first button is pushed.
• Output d is high when only the second button is pushed.

The last two outputs can be used to control the motor with the L293D.

i forgot to mention i have other appliances.. its suppose to be a home automation. its a school project. the sliding door is just a a4 size door.

helppppppp

Some schematics of the godfreyl idea... :-D

this was pretty helpful but the output pins of receiver all to 1 appliance? means one HT12D ic only can control one appliance?

mister_rf said:

Some schematics of the godfreyl idea... :-D

Click to expand...

Thank you.
I was sloppy - didn't realize the HT12D latches it's outputs when it receives a valid transmission.

benlim90 said:

this was pretty helpful but the output pins of receiver all to 1 appliance? means one HT12D ic only can control one appliance?

Click to expand...

Huh? Look at mister_rf's picture again. It shows how to control the motor and three other appliances (but only one at a time).

Learning about truth tables would help you understand how much stuff you can control with the four binary outputs. The transmitter can send 16 different codes to the receiver. What the receiver does with them is up to you.

i should learn the truth table of my 2 to 4 decoder ic right?

Yes, but I meant in general. For example, what if you want forward/reverse/stop control for 4 motors and on/off control for 4 lamps?

You can do that with one HT12D, but you'd need a 4 to 16 decoder instead of a 2 to 4 decoder. If you want completely independent control of all the motors and lamps, you'll need some latches as well, but still only one HT12D.

let say i wanna use row 3 and column 2 and 3 for my motor input. can u tell me where to connect? i wanna test it out.. im testing it right now.. my transmitter and receiver is working.. i used led to test.

Some clarifications about HT12E/HT12D circuits. :smile:
The HT12E is capable of encoding information which consists of 8-address bits and either 4 further address/data bits . For the HT12E encoders, transmission is enabled by applying a low signal to the TE pin. If a transmission enable signal is applied, the HT12E encoder scans and transmits the status of the 8 bits of address(A0 – A7) and 4 bits of data (AD8-AD11) serially in the order A0 to AD11. Each address/data input can be set to one of the two logic states. The programmed addresses/data are transmitted together with the header bits via an RF or an infrared transmission medium upon receipt of a trigger signal. Pins 1...8 of encoder are for setting the unique signal and important to set the same pins of decoder with identical settings, otherwise the receiver will not decode the signal.
Pins 10…13 are for data bits.




One bit gives us two combinations, two bits gives four, three bits gives eight, and four bits gives a total of sixteen combinations.
0000
0001
0010
0011
…
1100
1101
1110
1111
OK?
In order to transmit those combinations we need to provide each time a data word of 4 bits and a pulse on the TE pin.
If we leave the data pins not connected, this means logic high, data word = 1111, if we connect data pins to GND we change for logic low. This can be arranged using some external diodes. As for example
0000 = four diodes, each to one data input + one diode to the TE (transmit enable) pin
0001 = three diodes (D1, D2, D3) + one diode to the TE (transmit enable) pin
0010 = three diodes (D0, D2, D3) + one diode to the TE (transmit enable) pin
0011 = two diodes ( D2, D3) + one diode to the TE (transmit enable) pin
0100 = three diodes (D0, D1, D3) + one diode to the TE (transmit enable) pin
.....
1110 = one diode (D0) + one diode to the TE (transmit enable) pin
1111 = just a single diode to the TE (transmit enable) pin.
How many combinations we transmit it’s up to us to decide.
By the way, I have made some mistakes in the previous diagram. I was thinking sending 0000 status and end up by sending 1111 status for the STOP command. See the new diagram.

hmm.. i have a 4x4 keypad at HT12E. can u check out my transmitter circuit? currently my receiver, transmitter is working as a pair. but my motor circuit requires me to manually change the input pins to high-low,low-high..

By using the two separate sections of the 74139 allow us to use each two bits of four available on the encoder/decoder circuit and give us two groups for total of four combinations each.

One group to be used for the motor drive.
The motor section need to comply with the logical status of the L293D driver
00 = Motor stop
01 = Motor clockwise
10 = Motor counterclockwise
11= Motor stop
So we need to use two bits of the encoder, but in order to arrange not to interfere with the other appliances, we must keep the remaining two bits on STOP position.
Let’s define STOP position for all the appliances as 11.
Necessary codes for the motor section
1100
1101
1110
1111


We use the second decoder section for the remaining appliances. Same story, need no to interfere with the motor section, each data word need to keep a motor STOP condition (see the L293D driver logical diagram=> we can chose 00 or 11 as we wish) we chose 11 as STOP.
As in previous stage we have defined the appliances STOP = 11, still available 00, 01, 10 to be decoded as ON status for 3 more appliances.
Necessary codes to be transmitted (that’s an arbitrary decisions made for the decoded order to match the previous diagram I have made)
0011 – appliance 3 ON
0111 – appliance 2 ON
1011– appliance 1 ON
1111 –all appliances OFF

So I can see you are using a 74C922 circuit. In this case need to provide the correct TE signal to the encoder. There’s a ' Data available' pin, active high, this signal must be reverted to active low and connected to the TE pin.

In practice this can be done by using some inverter gate (also a NAND gate) or using a bipolar transistor.