Story

The RF detector can be used as linear instrument monitor or as threshold/comparator alarm, it depends from DipSwitch1-1 setting: On=instrument, Off=comparator. The threshold level comes from 10K trimmer you may set as you like. In instrument mode both buzzer and top panel RGB LED change their level (sound & light) depending of the detected RF power level. DipSwitch1-2 setting: On=buzzer on, Off=buzzer off.

By the way of DipSwitch2-1 and DipSwitch2-2 you may change the colour of the top panel RGB LED: 00=off 01=red 10=green 11=blue.

Additionally it is an USB mini connector to recharge the battery from an USB power source, and a red colour LED to show when it is charging.

Things used in this project

Hardware components
	Arduino Nano R3	×	1	Newark CPC
	Microchip ATtiny 1614 Processor	×	1

Inspired from John Bradnam's ATtiny 1614 Project I bought a couple of this microcontrollers to take a new way and enjoy a new adventure, I made MyTiny first testing circuit. Everything is working on my choice to power it at 3.3v. Up to today I tested and verified: digitalRead, digitalWrite, analogRead, analogWrite both PWM and DAC; I provided a serial monitor though pins RX/TX <-> FTDI serial interface and SoftwareSerial library; finally I connected an OLED 128x32 display by the way of SDA/SCL and Wire library. Cool!

ATtiny programming:

To program the ATtiny by the way of an Arduino NANO and IDE please read Bradnam's instructions at above link. Here some of it:

• install jtag2updi sketch into Nano
• connect a 10uF 25V electrolitic capacitor on Nano between RESET(+) and GND(-)
• connect a 4.7K resistor and a wire from Nano pin 6 to ATTINY UPDI pin
• connect GND from Nano to ATTINY
• connect +5V from Nano to ATTINY
• keep connected Nano and Arduino IDE
• change programmer to "jtag2updi"
• change board to "ATtiny1614..."
• change other parameters as per attiny-setup.jpg screenshot (see below)
• compile the sketch for ATTINY
• Upload sketch to ATTINY (try...)

Components list:

• LT5534 50-3000Mhz RF power detector IC
• ATtiny 1614 3.3V MCU
• LIR2450 3.6V rechargeable battery + PCB holder
• MCP73831 Li.Po. controller charger IC
• Active buzzer
• 2x two dipswitch
• 10k trimmer
• RGB 4 pins led
• Red led
• SMA-M (144-430Mhz small antenna)
• SMA-F panel connector, square + screws
• On/off switch
• 2x SMD 4.7uF capacitors
• 2x SMD 1nF capacitors
• 2x SMD 1.0uF capacitors
• SMD 10k resistor
• SMD 22k resistor
• SMD 47 resistor
• SMD 100pF capacitor
• SMD 470 resistor
• SMD SOT-23 662K 3.3V voltage regulator IC
• 3 pins connector for UPDI (1=UPDI, 2=3.3V, 3=GND)
• SMD USB-mini connector
• Plastic or metal box 51x51mm internal size
• 9x copper pass through rivets

Typical schematic diagrams:

NOTES:

• Capacitors and resistors SMD size is C1206;
• Components are small, and 5534 RF detector IC is VERY SMALL! To solder it I had to use an electronic magnifier!
• The 22kohm is the charging current resistor. The formula is: 1000/22000=0.045A (45mA). In the typical application schematic diagram shown above the resistor is a 2kohm, it means the charging current will be 1000/2000=0.5A, too much for this small coin battery. I had to modify it of course;
• Remember to connect a specific antenna for every RF frequency range you want to detect; in some cases a simple ring wire of any lenght can be enough as "antenna", specially when the RF signal is strong;
• LT5534 datasheet says to not overload the RF input pin with signals > 10dbm (i.e. handheld 5W radio tx near the IC); if it is the case, I suggest to put an attenuator between the antenna and the box (i.e. 20dbm SMA-MF serial external attenuator - see the picture below); additionally, use full metal box, or cover the interiors of the plastic box with copper foil, or paint/spray and 80°C cook if necessary (read material datasheet) with conductive material the interiors of the box (i.e. graphite), to avoid RF signals passing through the box; the RF signals should pass through antenna only... Burning the IC is a real possibility: I did it one time.

Enjoy it!

Schematics - PCB rf-sniffer top

PCB rf-sniffer bottom

PCB rf-sniffer topsilk

Code - RF-sniffer code

Arduino

Credits

marcozonca

"From an early age I learned to not use pointers"