Send data to weather station over 433.92 MHz (2)

In a previous post I used a software defined radio (SDR) to analyze and decode data transmission over 433.92 MHz of a simple weather station. As I mentioned then, the indoor unit can receive data from up to three outdoor units. I found that outdoor units use basic OOK modulation to send data to indoor unit. Knowing this I can make my own outdoor unit using a 433 MHz transmitter module controlled by an Arduino.

Obviously, I had to use a temperature and humidity sensor such as DHT11, DHT22, AM2302 to get environment parameters. I emulated full original outdoor unit functionality by adding a display and a push button to trigger immediate transmission of data to indoor unit.

Arduino based data transmission device

Decode 433.92 MHz weather station data (1)

I bought a simple weather station, with temperature and humidity display for indoor and up to 3 wireless outdoor sensors (sold with only one though). Unfortunately, the one I got, had a non-functional outdoor sensor. I took it back to the store and got a replacement for the entire product. The outdoor sensor can be hanged on a wall with a small screw, but it can easily fall down.

Given the facts I initially got a broken sensor, the weather station can receive data from up to 3 sensors and because sensors are exposed to outdoor conditions, I decided to analyze the wireless protocol and maybe build my own device which will be able to emulate this kind of sensor. There is no information about wireless protocol of this weather station (sold by Lidl in Europe under the Auriol brand), except the frequency: 433.92 MHz. That was all I needed. And a software defined radio (I used RTL2832U dongle).

A proper enclosure for CNC3018 Offline Controller

I like to have an offline controller for my CNC3018 machine because I want to keep my computer away from the CNC during usage. There is a lot of dust and cut material scraps which shouldn't get into fans and electronics. Speaking of electronics, the offline controller of CNC3018 is just a bare PCB stacked between two nicely machined acrylic plates. There is absolutely no dust protection. Here is issue #1. The next one is that this controller hangs around the CNC. There is no way to attach it to the frame. And the third issue one will encounter when using the offline controller is the loss of computer communication. That is right. If the offline controller is plugged in, you cannot connect to CNC via USB. Basically, both USB interface and offline controller share the only available serial port of the ATmega328p based mainboard.

I decided to fix all these issues. Following is a 3D printable enclosure which can be attached to the side of the frame on existing screws. And regarding the serial port issue, there is an optional cable connection mod you can do. Below is the result.

CNC3018 Offline controler attached to frame side

FreeCAD tools and settings for CNC 3018 Pro

I recently bought and assembled the CNC3018. I have never owned a CNC before and I was unpleasantly surprised by the lack of free and easy to use software to produce CNC jobs. So I had to learn FreeCAD, the only open source software known to me which can be used for this purpose. In this post I added the two types of tool bits supplied with the CNC to FreeCAD's library and I will attempt to produce various jobs in future posts.

CNC machining is a complex process and its workflow depends on a lot of interrelated parameters unknown to beginners. Setting them properly is an absolute requirement to complete a CNC job without breaking valid bits, ruining the work piece or damaging the machine.

CNC 3018 Pro Z axis coupler adjustment

The first thing people tell you when you start doing CNC is that you will break some bits. It happened to me too. I checked the gcode before sending it to CNC so I wouldn't ram the bit into the work piece or the base plate. But, with my CNC 3018 Pro another thing happened. The spindle could no longer be lifted (Z axis movement failed).

CNC 3018 comes as a kit. With the exception that in the newer batches of this product, they decided to ship it with preassembled Z axis assembly. Obviously, I assembled the machine and didn't pay any attention to the Z-axis. Until I had to. The lead screw slipped from the shaft coupler during a job and the bit nearly got to the base plate before breaking. Then I realized there were some problems with the Z axis assembly.

Spindle at its maximum Z height with short shaft stepper

Update GRBL firmware on CNC 3018 Pro

CNC 3018 Pro is a low-cost CNC router that should be used mostly with wood and acrylic plastic. It can also be used to mill PCBs and cut soft metals like aluminum with proper settings. The machine uses both metal and plastic parts. Electronics is based on a custom made ATmega328p board with A4988 stepper drivers. Spindle uses a common DC775 motor fitted with ER11 chuck.

I recently bought one from Banggood (I chose the version with offline controller because it allows me to load gcode from SD card and use the CNC without a computer next to it). To my surprise it came with an old version of GRBL firmware (0.9j) so I started gathering information about how I can update it.