Vermes
Advanced Member level 4
What was used:
- two modelling servos
- worn chain and sprockets from a bike
- 2PMR (private mobile radio [shortwave transmitter])
- 4xAA 2700mAh battery
- 4xAAA 900mAh battery
- the body is made of aluminum combined with steel screws
The corpus:
Electronics:
The schema
The steering board
DTMF decoder
H bridge – schema:
Microchip:
Sending commands uses a DTMF (Dual Tone Multi Frequency) system, which uses MFSK (Multiple frequency-shift keying) modulation.
The DTMF signal is created to send by audio tone therefore is ideal to send it by any sound device (phones, CB's, VoIP etc.). This platform uses two old shortwave transmitters.
The transmitter contains two devices – a shortwave transmitter and a DTMF generator, a nokia 6120 mobile phone. The devices are connected by a headset (jack2.5 ↔ jack2.5)
Decoding the DTMF is done by MT8870.
A high state is set on the StD output of MT8870 when a correct DTMF code is decoded, and the code of the of the received key is set on q1-q4 outputs.
For example:
When a button on the telephone is clicked - a high state is set on StD output and 1001 is set on q1-q4. When the button is released - a low state is set on StD output and 1001 is set on q1-q4.
Link to original thread (code, film, attachments) - T102-zdalne sterowany pojazd gąsienicowy (Robo-platform)