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new projects on Open-electronics.org:
Connected to a burglar alarm or fire alarm in the event of making phone calls playing voice messages. Controlled via DTMF actuators can operate on the spot.
In recent years we have introduced several telecontrols based on the SIM900 GSM module. We released schematics and code for a gate opener (that activates when receiveing a call from a given number), a GSM thermostat to manage the temperature of remote houses with simple text messages, a remote alarm control with DTMF and, last but not least, a remote alarm with I/O and controlled via calls or SMS.
Many of these tools send text messages or place phone calls in response to changes to the electrical inputs. In some cases, especially when the receiver is a human, nothing is like a voice that clearly yields you screaming “fire in progress!”, or”thieves in the house!” etc.
GSM Voice Dialer with Automation Control - [Link]
open-electronics.org writes:
Using an ATmega 2560 and therefore the heart of Arduino, we have developed a universal remote control with GSM. This allows to control 2IN/2OUT, DTMF key, gate control and GSM thermostat activated remotely.
We have already presented several remote control with different functions. But now we want to present the best remote control ever made with Arduino.
The remote control is easier, thanks to the availability of several libraries that allow you to do anything to the Arduino microprocessor; if there is not really a specific library, you can modify an existing one. Thus was born TiDiGino, based on the chip ATmega 2560 used in Arduino Mega. Our system has connectors S.I.L. to mount any shield, each of them is in the same location where you would be in the original development platform, which enables the use of commercial and in any case the standard shield.
We said that the functions of our remote control, ie 2IN/2OUT, gate opener, key DTMF GSM and thermostat can be achieved by using special firmware, well, we could write these ourselves, but we wanted to offer our readers who know the Arduino environment do them. This is the sense of TiDiGino Contest, which you could follow our blog and that has just ended, as promised, we publish the hardware of the remote control and a few routines.
TiDiGino - the Arduino-based GSM remote control - [Link]
timnolan.com writes:
This is a project I did a couple of years back for a business friend of mine to automatically log all his phone calls into his computer. The hardware (pictured above) uses an microprocessor to monitor the phone calls (incoming and outgoing) and send the data out the serial port to be read by the computer.
The hardware is controlled by an Atmel AVR ATmega32 microprocessor. The processor uses optoisolators to see if the phone is off-hook and to check if the incoming line is ringing. If the phone is off-hook a DTMF decoding chip CM8870CP is used to decode the number that is dialed. If it is an incoming call an FSK decoding chip XR2211 is used to decode the Caller ID data.
Phone Call Logging Project - [Link]
electronics-diy.com writes:
DTMF tone is mainly used in telecommunication technology, such as dialing a phone number, handling various services over the telephone, as a selective choice of radio stations, etc. The individual characters are assigned to different pairs of tones. The described decoder Received characters on the LED display, and stores them in memory, where they can be retrieved later.
DTMF Phone Decoder – [Link]
electronics-diy.com writes:
Today, most telephone equipment use a DTMF receiver IC. One common DTMF receiver IC is the Motorola MT8870 that is widely used in electronic communications circuits. The MT8870 isan 18-pin IC. It is used in telephones and a variety of other applications. When a proper output is not obtained in projects using this IC, engineers or technicians need to test this IC separately. A quick testing of this IC could save a lot of time in research labs and manufacturing industries of communication instruments. Here’s a small and handy tester circuit for the DTMF IC.
MT8870 DTMF Telephone Dial Tone Decoder - [Link]
PicCon is a PIC microcontroller based radio controller designed for hidden transmitter hunting. When combined with a radio transmitter, it will produce tone sequences and Morse code messages at user-programmed times. It is completely field programmable via DTMF tones, utilizes EEPROM for all programmed options so they are remembered when power is removed, and is quite compact.
PicCon : Hidden Radio Transmitter Controller – [Link]
This project uses a cellphone interfaced via an MT8870 DTMF decoder and an Atmega16 to operate servos controlling a robotic car. Check circuit and construction details on the link below. [via]
Cellphone controlled Robot - [Link]
DTMF-remote – Activate relays with your smartphone - [Link]
This project was designed and implemented an electronic phone directory which has a built-in automatic dialer. The electronic directory allows user to Dial, Enter, Search and Delete entries. When dialing, the Atmel 8515 microcontroller will generate the Dual Tone Multi Frequency (DTMF) signals corresponding to the phone number being dialed. To avoid building the phone circuit for the dialer, a DTMF decoder was used to detect what number is dialed by the user. [via]
Electronic Phone Directory and DTMF Generator – [Link]
There are many versions of DTMF decoders outside the Internet, but all are doing pretty the same – decoding dual tone codes in to digits, that can be later interpreted by microcontroller. This device uses an integrated decoder chip MT8870DE which decodes all 16 DTMF tone pairs in to 4 bit code.
AVR Microcontroller reads these codes and outputs them to LCD as characters. DTMF receiver stores last 234 received digits in EEPROM that can be viewed by scrolling an LCD character line. DTMF Decoder also can be connected to PC via RS232 interface. So each time TDMF signal is received it sends digit to Terminal. Program is written by using free WinAVR GCC compiler tools. [via]
AVR DTMF decoder based on MT8870DE - [Link]
