Circuit Lake

Another cool microcontroller project created by Klaus Stock. He said, this is a simple IR receiver circuit which plugs into a serial port of a computer. This circuit has two major advantages:

1. it uses an Atmel AVR RISC microcontroller (an AT90S2313) instead of the usual PIC microcontroller and
2. it uses a Maxim MAX232 for the generation of valid RS232 levels.

Advantage 1 is, of course, only valid for all those AVR addicts which have this device (and the corresponding programmer) ready at hand and don’t care about PICs and PIC programmers. Advantage 2 comes into play if the IR receiver has to placed at a great distance from the computer; the MAX232 is more likely to deliver valid signals over bigger distances than cheaper solutions.

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This decoder is fed by a RDS demodulator IC (or tuner) which has RDDA (data signal) and RDCL (clock signal) outputs.The microcontrolller is an Atmega168 clocked on the external 4.332MHz crystal from the RDS demodulator. TDA7330B RDS demodulator IC from STMicroelectronics to be used in this project. The TDA7330B is connected to the Atmega168 with RDDA connected to PD4 (on PORTD) and RDCL to INT0 (PD2).

The software in the Atmega168 is able to decode the following RDS data:

* Programme Identification code (PI: 0×83C7, Detected new station.)
* Program service name (PS: RADIO538)
* Programme Type code (PTY: 0×0A, Pop Music.)
* Traffic Programme Identification code & Traffic announcement code (TP&TA: 0×01 0×00, Traffic announcements available on this station and maybe via EON on another station.)
* Music Speech switch code (MS: 0×01, Music is being broadcasted or station does not use MS flag.)
* Decoder-identification control code (DI: 0×01, Stereo, Dynamic PTY.)
* Alternative frequency codes (AF: 0×98, 102.7MHz.)
* Linkage Actuator (LA: 0×00)
* Extended Country Code (ECC: 0xE3)
* RadioText (RTA: Radio 538 = Randstad (Zuid) 102.7 FM)
* Clock-time and date (CT: 0×1A53CD844, UTC 2006-07-02 (MJD 53918) 13:33:00 +02:00, TIME 15:33:00)

Download for document, source code here (zip)

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There are serveral rs232 transceiver circuit which commond used for communicated between microcontroller and other devices such PC or any devices that use rs232.Here is a collection of rs232 transceiver circuits that popular for today.

2 transistor
The circit below use 2 transistor and some components to provide RS232 transceiver.It usefull for cheap application that dose not long lenght.

Fig 1. Transceiver with 2 transistor

Read more RS232 Transceiver Circuits

The “Birth Clock” is a fragile glass object containing a digital clock that is not working; it is designed to help you to come to a decision when you’re stuck at a specific point in life. Smash the glass, and the clock will start to work, leaving you with the broken object as a reminder of your dramatic decision. Leave the object as it is, and you remain out of time, having the beautiful object as a reminder of your resistance to change. What would you do?

Birth Clock [link]

This project uses 2 AA size rechargeable NiMH batteries (1.2V 600mAH) being recharged by the solar panel and also has a conventional battery holder for 2 more AA size cells in parallel with the rechargeable ones. Thus, if the conventional cells are low you may always recharge the other battery holder. Suggested uses for this torch are: bike, car and at home.

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This instructable will show you how to create a multifunction platform with a thermometer, chronograph (count up timer), count down timer, and light display. It is also intended to be a platform for other analog sensors or any other functions you can think of. Project is based on Atmega168 microcontroller. Information is displayed on dual 7 segment LED display.

Multifunction Digital Thermometer [link]

This is a really cheap and probably illegal shortwave transmitter, don’t build it. It just feeds the output from an LM386 audio amplifier directly into the power pin of a crystal oscillator can to produce AM-modulated shortwave radio frequencies. This works better than one might expect — this particular oscillator seems to provide a stable waveform with voltages anywhere from 2.0v to 5.0v!

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