433 MHz module - sensor to arduino communication

hello, i'm kind of new to wireless communication and arduino so i'm a little bit confused about some things..
the project that i was interested of making involves the use of HC-SR04, an lcd, and an arduino uno. initially, the plan was to use the arduino and the ultrasonic sensor(HC-SR04) to compute and display the distance in the lcd. however, i was asked to make the sensor and the lcd located at different locations which made my project a little bit complicated.

so i found this 433 MHz module which uses ASK modulation which from my understanding, transmits high frequency modulated by digital signals. so i thought since the output of the sensor is digital, is it possible to just directly connect it to the transmitter module and then connect the arduino uno at the receiver side to use pulseIn for the computation of distance and the display for the lcd?

i plan to trigger the sensor using astable 555.

i've research about the module and all i've seen are examples which uses arduino on both sides(TX & RX).
the module= https://camo.githubusercontent.com/fa227706371d8533e596afe5c70b9645ddc34bee/687474703a2f2f696d672e62616e67676f6f642e636f6d2f696d616765732f75706c6f61642f323031322f6368656e6a69616e7765692f534b553036343438372e352e6a7067
the sensor= https://www.aimagin.com/media/catalog/product/cache/1/image/9df78eab33525d08d6e5fb8d27136e95/h/c/hc-sr04-02.jpg

The ASK modules can turn the transmitter on and off, that is not even a real "modulation".
The receivers have automatic gain control, they receive noise when nothing is transmitted.

What you want to do might work a little at a distance of 50 cm.

For distances of a few meters and up to 30 meters, you need a serious library that transmits data with a certain protocol and the receiver code should be able to distinguish that data from the noise.
That is why everyone is using VirtualWire or RadioHead. That library is by far the best library for ASK modules.
RadioHead: RadioHead Packet Radio library for embedded microprocessors (with RF_ASK)

It will only work when both the transmitter and receiver use an Arduino. You don't need a 555 chip.

that means the only way i could get a satisfying output is if i use 2 arduino unos; one RX, another for TX?

i was actually gonna use the 555 for trigger of the sensor since i planned on not using another arduino for the TX side.

Use two Arduino boards and a good library.

If you have enough time, you could do a test. But instead of using a 555, use an Arduino board, and transmit the HC-04 pulse directly with the TX module. Trigger the HC-04 perhaps 10 times a second. You should be able to receive that pulse. It will be only for short distances and it is unreliable. Maybe it will be good enough for a quick demonstration ?

You can use cheap arduino clones like the pro mini or nano, they are small and work just like the uno.

I was actually browsing through other threads and it seems that the ask module doesn't really modulate any digital data instead it waits for binary data to be modulated. And with my sensor,the output isn't binary but something like a pulse width variation or something. Anyway thanks for the replies. :slight_smile:

It does not wait. Maybe a library waits.

The ASK TX module :

  • data pin high, then it transmits at 433MHz.
  • data pin low, then it is doing nothing.

The ASK RX module:

  • It has automatic gain, and receives either data or noise.