Ok, as an extra part, here is the schematic that I've made with the reverse engineering of the small 433MHz radio mdoules. You have the scheamtics below if you want to make your own mdoules and also you ahev the GERBERs if you want to make the PCB as well. You will need a 433MHz crystal and some coils. All components are on the schematic.
Let’s start with the ATtiny85 chip. This is an 8-bit RISC microcontroller and sometimes it’s also called a small Arduino. It has 5 IO pins, all 5 can be digital, 3 of them can be analog inputs and two could create PWM signals. To program this chip, we need an SPI communication. My code will use the "micro" function as well, and after searching online, I’ve found that the ATTINY could use those functions only with an 8MHz bootloader. We will reate a shield for the ATtiny85 following the schematic below that can then be connected to an Arduino Uno.
The shield is ready. Plug it into the Arduino UNO and put an ATTINY 85 into the socket. Make sure which is pin one and don’t put the chip reversed. Now connect the Arduino Uno to your PC. Now, pay attention. Right now, I’m using the latest version of the Arduino IDE, which is the 1.8.7. But for some reason the ATtiny85 boards won’t work with this version. For that, go below in the description and download the zip file with the Arduino IDE version 1.0.5.