The ArduTrx Shield with an Arduino and a display board mounted in a self made wooden case. Completed with a 2S lipo battery, an antenna and a Kenwood-compatible hand mic ready for its first QSO.
The ArdTrx project consists of two parts: the ArduTrx shield and the software. Both parts can be used independant from each other.
The ArduTrx shield is an Arduino shield with a HF module and surrounding circuitry. The shield plugs directly into the pin header of the Arduino Uno or compatible board and forms a stack with it. Other shields can be plugged on top or in between.
The ArduTrx software utilizes this shield but could also be used with a compatible HF module on a breadboard. To get a useful HMI it is suggested to plug a SainSmart 1602 LCD Keypad Shield (https://www.sainsmart.com/products/lcd-keypad-shield-for-arduino-duemilanove-uno-mega2560-mega1280) on top.
The hardware is built around the popular HF modules from Dorji or NiceRF and utilizes all necessary circuitry to get the module running and audio in and out of it.
A HF module from Dorji or NiceRF is used on the shield. 2 meter (144 MHz) or 70 centimeter (440 MHz) modules can be soldered.
Unfortunatelly these HF modules produce spurious emissions. Therefore a HF filter is implemented on the shield. It is a chebyshev low pass filter and has a cutoff frequency of 185 MHz.
The HF modules allow a maximum voltage of 4.5 V (Dorji) or 5.5 V (NiceRF). Arduinos usually don't provide these voltages. But you only get the maximum HF power if you go to the voltage limits. Therefore ArduTrx uses a adjustable power regulator LT1085. The desired voltage can be set with the resistors R15 and R17. Additionally the modules draw up to 750 mA while transmit. This is too much for the voltage regulators on the Arduinos. The LT1085 on the ArduTrx shield can provide up to 3 A.
To make the audio output of the HF module hearable you need a speaker and an audio driver. ArduTrx shield uses a LM4871 which is optimal for battery powered circuits with low voltage and can drive high power with its differential output. The speaker can be connected to CN6. It is also possible the drive single ended loads like head phones on CN4.
ArduTrx can be used with 3.3V and 5V arduinos and these level shifters guarantee the right voltage level on the transmission lines.
The rotary encoder is only connected to the pins of the arduino and has no connection to the HF module. It can be used in Arduino programs to set the frequency of the HF module.
The HF module needs a serial input from the arduino to change its configuration. Unfortunatelly this serial port of the Arduino is also used during programming of the Arduino and generates programming errors if it is also connected to HF module. So ArduTrx has a switch to open the serial connection to the HF module and allow programming (switch in off position). The switch has to be turned on if settings to the HF module have to be made.
This connector has the same function as the coaxial power connector on the Arduino board. It only uses an industrial connector and allows a safer connection. The input voltage can be measured with R35 and R36.
The antenna connector is a SMA connector like it is used on many Hand-helds.
CN3 and CN4 form a hand mic connector which is compatible to Kenwood or Baofeng.
|Arduino pin||direction on Arduino||usage|
|0/RX||input||serial communication with HF module|
Attention: also used for programming the Arduino
|1/TX||output||serial communication with HF module|
Attention: also used for programming the Arduino
|2||input||squelch. low=RX active; high=no RX|
|3||output||analog / pwm audio output; for example for 1750 Hz tone.|
|11||output||PTT: low=no TX (RX); high=PTT active|
|12||output||Power down: low=sleep mode; high= normal mode|
|13||output||Output power: low=1W; high=0.5W|
|A1||input||measurement input for VIN or serial input of GPS|
|A2||input||audio input to Arduino|
|A3||input||rotary encoder signal A|
|A4||input||rotary encoder signal B|
|A5||input||rotary encoder switch|
|IOREF||-||reference voltage for level shifters (U4 and U5)|
|VIN||-||input voltage for voltage regulator (U2)|
|5V||-||supply voltage for CN5 (GPS connector)|
|Designator||Package||Quantity||Value / Manufacturer and Partnumber||Reichelt order number||other order number|
|C1,C4||C_0603||2||30p||KEM C0G0603 30P|
|C13||C_0603||1||1u||KEM X5R0603 1,0U|
|C15||c_elec_8x10.5||1||470u||HA-V 470U 16|
|C2,C3||C_0603||2||47p||KEM C0G0603 47P|
|C5,C7,C8,C10,C11,C12,C14,C16,C17,C18,C19,C20||C_0603||12||100n||KEM Y5V0603 100N|
|C6,C9||C_0805||2||10u||KEM X5R0805 10U|
|CN3||1503_07||1||Lumberg 1503-07||LUM 1503-07|
|CN4||1501_03||1||Lumberg 1501-03||LUM 1501-03|
|D1||LED_0603||1||Led red||SMD-LED 0603 RT|
|D2||LED_0603||1||Led yellow||SMD-LED 0603 GE|
|D3||LED_0603||1||Led green||SMD-LED 0603 GN|
|Q1,Q2,Q3||SOT-23||3||2N7002||2N 7002 SMD|
|R17||R_0603||1||300||RND 0603 1 300|
|R19,R20,R36||R_0603||3||20k||RND 0603 1 20K|
|R23||R_0603||1||2k||RND 0603 1 2K|
|U3||SOIC-8_3.9x4.9mm_Pitch1.27mm||1||LM4871||LM 4871 M|
DNI means do not install. Leave this part unpoplated.
The software utilizes the ArduTrx shield on any compatible board. Together with an HMI board it creates a complete hamradio transceiver.
You can find the software on github: https://github.com/generationmake/ArduTrx
The software is released under GPL v2
The fully assembled shield ready to plug into an Arduino board
Close-Up of the display and HMI with keys and rotary encoder
This was the first prototype
If you have any questions contact me via email at email@example.com, make an issue at github or send me a message at twitter (https://twitter.com/generation_make).
Last update: 02. dec. 2018