Breakout boards for the HopeRF RFM23BP 433MHz modules with SMA connectors. Fabricated by the famous Magic Purple PCB Factory 😉




These modules come in different operating frequencies and are supposed to transmit with up to 1W. They communicate via SPI and need up to 600mA (max. output power). The power can be set in software. I made them for long range telemetry purposes, but will not operate them at full power, since a license is needed for output powers above 10mW, even in the free ISM (Industrial, Scientific and Medical) band.









The modules have a blank ground plane without solder mask on the bottom side. A special soldering technique was used here: I tinned this blank area and filled all those vias on the breakout board with solder. Then I applied flux to both the module and the board and finally soldered them together by holding the sandwich against my cooking plate. This will make perfect heat dissipation from the power transistor.









Eagle board files:




RFM23BP

While browsing some adafruit pages I came across this one.
I thought it would probably be useful to have completely hackable scales for some future project or just for household use and so I adapted the hardware frome the above tutorial.




Since I was only able to find the SMD version of the INA125 I had to make a PCB again, but this is not my first DIY PCB, so the process was pretty easy.









If you are looking for small load cells on ebay or similar shops, you will probably figure out that a cheap mini scales (around 4€) is even cheaper than a single load cell of comparable size (5€). This is why I purchased the complete device rated for up to 1 kg and disassembled it. Prior to taking it apart I measured the weight of some small household items to use them as calibration weights later on in the calibration process. The second advantage you have when getting complete scales is the flat and stable platform mounted on the load cell for you so you don’t have to do it yourself.
Here’s the complete scales on a breadboard. For wiring of the analog part with the microcontroller check the tutorial above.
The load cell was mounted to an acrylic plate with a piece of aluminum in between for stable weight distribution.









Here’s the schematics and the board file for the SMD INA125 (as always in eagle format):




Load Cell Amplifier




Update: After finding the HX711 breakout board on ebay I upgraded the scales board to this interesting part. It’s a 24 bit ADC that can communicate to a microcontroller over a synchronous serial protocol. It is specifically designed to amplify signals from load cells and gives you a higher resolution (0.1 g). Several Arduino libraries for this chip are around.

TV-B-Gone clone with LiPo battery charger and 1W infrared LED

Arduino-Android CC3000 Wifi chip-based Telnet Interface









This page provides some guidance on how to set up a wifi connection between an Android device and a minimalistic arduino-based server. The wifi chip used in this project is the CC3000.




Tutorials on how to get the CC3000 to work with the Arduino are all over the WWW, what I would like to add is an example on how to have the Arduino talk to a smartphone or similar.




The communication protocol used here is Telnet. The data comes from a DHT22 sensor which measures humidity and temperature. Actually this is an extended mashup of the open home automation and the candy bowl project. The Android App uses client sockets to communicate to the arduino, which operates in server mode.




Android App Code (ADT Eclipse project):




TelnetClient




Arduino Code:




CC3000_Telnet_server_DHT22

This is a huge 4-digit i2c display based on an Atmega8 @16MHz which operates as a i2c slave and does all the multiplexing via timer interrupt. The display is composed of four sa23-12srwa seven segment displays (common anode) with a digit height of 57mm. The firmware for the Atmega8 was written in AVR Studio in C.




It can be addressed simply connecting it to an Arduino and using the wire library. Whenever an ultra-readable bright digit display is needed that is easy to use, this one might come in handy. Some projects I thought of were an oldschool thermometer clock or a distance-measuring device for the garage entrance.









The anodes are driven using an ADN2981 driver and are attached to PB0…3. The cathodes take up the entire PORT D and are driven by a ULN2803. Those drivers are necessary, since the segments (except for the decimal point) are several red LEDs connected in series dropping ca. 7.4V. One does not simply connect one of those to a blank microcontroller port.









Source code for the Atmega8 (AVR Studio, C) as well as the Arduino which acts as a I2C master:




I2CjumboDisplayFirmware

// Functions to talk to the DIY jumbo LED four digit display board



#include <Wire.h>

void setup()
{
  Wire.begin(); // join i2c bus (address optional for master)
}



void loop()
{
  for(int i = 0; i < 10000; i++){
    ledDisplayInt(i);
    delay(30);
  }
}

void ledDisplayInt(int number){
  int number_disass = number;
  int Digit_X000, Digit_0X00, Digit_00X0, Digit_000X;
  Digit_X000 = number_disass/1000; 
  number_disass %= 1000;
  Digit_0X00 = number_disass/100;  
  number_disass %= 100;
  Digit_00X0 = number_disass/10;	  
  number_disass %= 10;
  Digit_000X = number_disass;
  Wire.beginTransmission(40); // transmit to device #40 for some reason it addresses a slave with the address 0x50
  //Wire.write("x is ");        // sends five bytes
  Wire.write(byte(0));  //begin
  //sending 0...9 displays the digit, sending 10 makes digit dark
  if(number > 999){
    Wire.write(Digit_X000);              //thousands
  }
  else{
    Wire.write(10);   
  }
  if(number > 99){
    Wire.write(Digit_0X00);                //hundreds
  }
  else{
    Wire.write(10);   
  }
  if(number > 9){
    Wire.write(Digit_00X0);                //tens
  }
  else{
    Wire.write(10);   
  }
  Wire.write(Digit_000X);                //ones
  Wire.write(4);                //decimal point position (0...3, 4 is no comma)
  Wire.write(1);                //display on/off (0x00 => off)
  Wire.endTransmission();    // stop transmitting
}