EFN PG03 MiniGPS Hack’s

I have just retrieved a small gps buy from ebay, called Mini GPS (enf pg03), cost around 20€ …pl410961-mini_navigator_dt_efnpg03_displaying_accurate_time_synchronized_by_satelliteIt is a small size and portable GPS receiver with data collecting and calcualating functions. It also provides indication of geograpic coordinates, directions, world time, distance, milage, and velocity information. Its high-sensitive direction indication guide user to go back original departure position or go to the presetted target position. The unit shows clear travelling date in detail, such as, the direction of the target position, distance, satellite time, and velocity information in usage.

This small unit do not provide to record tracking informations … so we start to disassemble it, in the goal to catch NMEA sentence, he work with a Venus638FLP chip.

After putting the prob of scope on the pin number 44, we got a signal. The idea is to collect this data and record it in a file on sdcard or memory.

2014-04-11 21.14.052014-04-11 21.11.34

Ardui’Home, temperature and gas alert for home

Updated [24/02]

I’ll move in a new apartment very soon, and i have the idea for a new domotic project, ArduiHome, a Arduino Uno, GSM/GPRS Shield, some sensors to measure temperature, humidity, and gas.

The goal of this project is to display, on a LCD, the temperature from four areas.
Sending back temperature and/or humidity value via SMS (no needed at this moment).
Send an alert when town gas or carbon monoxide reach a critical level.
Drive a relay to turn on lighting, or heating system (no needed at this moment).

- A ArduinoUno or Atmega328P.
- A GSM/GPRS Shield.
- 3x DS18S20 temperature sensor (1x bathroom, 1x sitting room, 1x outside).
- Humidity sensor to be defined, maybe DHT22 in two bedroom.
- Natural-LPG Gas sensor and Carbon Monoxide, (MQ5, MQ7).
- LCD 4×20, with I2C interface, to save I/O.

Right now i do some test with GSM/GPRS shield from ebay, GSMShiled

this shield is cheap , but appear only run with gsmlib libraries, from www.open-electronics.org.

Actually the code do:

- Read and display temps on a 2×16 LCD, from two temp sensor, i wait to receive my 4×20 LCD soon.
- Send SMS when the pin A0 read high value from MQ-5/MQ-7 gas sensor.
- Blink a LED to check if CPU run Ok.



To be implemented:

- Display temp and humidity from a DHT11 (2x Bedroom).
- Send temperature value from sensor’s via SMS.
- Check if letters come into the mailbox. Yeah, from postman.
- Drive a relay to turn on a light, or heating system.


Updated [24/02]

I have updated the code, i have just receive my 4×20 LCD screen, now i can display temperature from three DS18B20 sensor’s, alternately with DHT11 sensor (2x Bedroom). I have shorten the « too big » antenna of GSM shield :)

ArduiHome Test code

Build a powerful accuracy power meter for some $$$

I have spend many many hours over Internet with the hope to found a simple but accuracy watt-meter, and i have finally stumbled on the… Trinity Virtual RF Power Meter.

I encourage everybody that looking for a powerful simple power-meter to build the Trinity RF meter, designed by Daniel from rfcandy.

Most important features:

  • Wide frequency range 10 MHz to 2.5 GHz.
  • Measure down to – 60 dBm (0.001 uW or 0.225mV)
  • Absolute and relative power measurement
  • Present measurement in dBm, Watt, Volt and Screen Gauge Meter
  • External Gauge Meter for accurate reading
  • Digital filtering to reject 50/60 Hz noise
  • Optical communication barrier to prevent noise
  • DC input blocking
  • No complex trimming
  • Self-test with LED indication


(To reduce the cost, if you don’t want to buy the full kit, you can order only the pcb and the preprogrammed PIC).

2013-11-05 20.35.532013-12-09 17.57.21 (Small)

Don’t buy shitty DDS Function Signal Generator Module Sine Square Sawtooth Triangle Wave from ebay …


2013-11-05 19.03.38I have recently buy from ebay a small board called « DDS Function Signal Generator Module Sine Square Sawtooth Triangle Wave « , first its not a DDS like you think … yes, the wave are produced by a Atmega16, and the signal is very dirty, there is no any output filter.

If you are looking for a true DDS generator, look here

Trackuino APRS Beacon, designed for vehicles.

I work right now on the Trackuino APRS Beacon, but especially a version for vehicles.  Trackuino is a APRS tracker based on Arduino. Is intended for use by licensed radio amateurs. « By operating on the standard APRS frequency, the signal can be picked up by an Internet gateway and reported on www.aprs.fi, so anyone with an Internet connection can track the beacon in live ». I’ll add two temperatures sensors for monitor indoor/outdoor temperatures.

A first idea of the system, the project is under prototyping.


Retro engineering on a pager, Tatoo Hack

This hack, backward me in 1996/1998 during my college years, the pager system was at its peak, there was 3 commercial services and networks here, in France:

  • TamTam, the Cegetel/SFR paging services, stopped in 1999, using ERMES protocol.
  • KOBBY, from Bouygue Telecom, stopped during 2005, using ERMES/FLEX protocol.
  • TATOO, from FT/Orange, using POCSAG, the only still functioning, right now, since 2000, exploited by a Deutsch company, E-Message.

The Kobby and TamTam use VHF frequency band (Update 18/03/14 – 169,425-169,800 Mhz), and the TATOO receiver use UHF band (466.025 MHz – 466.05 MHz – 466.075 MHz – 466.175 MHz – 466.20625 MHz – 466.23125 MHz.). POCSAG protocol is basically easy to decode, with software like POC32 or PDW

« POCSAG is an asynchronous protocol used to transmit data to pagers. The name comes from Post Office Code Standardization Advisory Group, this being the British Post Office which used to run nearly all telecommunications in Britain before privatization. The modulation used is FSK with a ±4.5 kHz shift on the carrier. The high frequency represents a 0 and the low frequency a 1. Often single transmission channels contain blocks of data at more than one of the rates. »  wikipedia

Bellow is a dessication of a MOTOROLA MEMO Pager Receiver (Tatoo, commercial name).


The pager is composed of two circuits,  a board with a displaying circuit for the lcd, a vibrator, a piezzo buzzer, a backup batterie for the RTC, and a MC68HC68 microcontroler, he probably contain the program to decode/translate the signal and pager ARP address.


The another board is dedicated to RF reception, you can see a antenna, simple loop of metal, probably a narrow rf input filter, and a strange unidentified IC « 99Z32″, maybe a RF IC Receiver …


Now the goal is to identified the pin’s function on the connector. I have already put my Rigol probe on the Pin 4,  and i can see a low/high signal (see bellow). I’ll will try to translate this signal for PDW or POC32 software soon. Any help is welcome.


 Update 26/04

I started to listening the signal (blue) from my UBC 785 on 466.20625 Mhz, in parallel with the signal from the pager (yellow), it seem to be a inverted signal.


After feed the signal through a Max232, but no good result with the decoder software! *sic*, maybe need a little amplification before …



FM-Broacaster with Arduino and NS73

Few months ago, i have been looking for a robust easy FM broadcast solution, basically, i want simple solution, not the classic complex plan like > Stereo encoder = PLL = VCO = PA … < after some investigations i have found the NS73M FM Transmitter module from Niigata Seimitsu Co is a hight quality transmitter IC, can be controlled by a controller (via SPI/I2C), the features are:

87.5 – 108 Mhz Coverage
Stereo Modulation
Very Small package
I2C or SPI control
No tuning
Low Cost

The source of the project come from here and here

I have made 3 boards for this projects:
ArduiFM_Unit, its the main board with the NS73 and controller (Atmega328P)
BackConnector, the back board with input-sound, jack/RCA, and RS232 connector (future option for RDS)
Control_Cmd, is the front board with the button, up/down/backlight/set

The one of disadvantage have found is not RDS possibility because the sound is already modulated and mixed into the NS73, you cannot add signal.



right now, you can see the main µC board, LCD, audio connector, IHM board mounted, a DB9 connector is installed for a RDS future option. Now, the project need a power amplifier … stay tuned.