AVR

These are simple AVR programmers. I designed and built four different programmers for various envilonments: LPT controlled parallel programmer, LPT controlled ISP adapter, COM controlled ISP adapter and COM controlled generic SPI bridge. Additionaly, COM controlled adapters can be used as a communication cable between host PC and target board, it is useful for debugging.

The circuit in Figure 1 provides a novel method of reading the pulse train using an Atmel (www.atmel.com) AVR processor, from a typical radio-controlled receiver, and to determine the velocity of a motor. To capture the pulse train from a typical receiver, you need an external interrupt that triggers based on a rising and a falling edge.

This is a simple IR receiver circuit which plugs into a serial port of a computer. Okay, there are many other circuits of this kind, and most of them are even simpler, but 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.

This is a simple display controller. It can be controlled with a small microcontroller, such as MCS51, 68HC11, Z80, AVR and others. Several years ago, I found an article that controlling a TV with only a PIC micro controller, and I surprised to it. It is very interesting to attempt to synthesize video signal with a micro controller.

This is a simplified version of SI Prog from Lancos, suitable for beginners and is very reliable.

The Atmel AVR series are very good microcontrollers with quite a rich instruction set, rich enough that lots of folks have good compilers for them so we don't have to learn their assembler. A very rich compiler available is the BASCOM/AVR compiler from MCS Electronics. I've used this compiler for prototyping the software on my 90S2313 robot board for two reasons: One, It has a very rich command syntax; Two, its free in its demo version! The demo version only supports 2K of instruction memory, other than that it is completely uncrippled.

A very simple circuit to experiment with AT90S2313, 2x16 LCD display and 4x4 keypad. The clock based on 4 MHz crystal, but you can use anyone crystal between 1-4 MHz. The keys with the name "A", "B" ... "F" are typed to the LCD with numbers 10-16. Because the AVR have only 15 I/O pins we are working the LCD display with 4-bit databus. The 4 resistors (10K) are to protect the AVR from the shortcuts as the coloumn of the keypad is change. I make the source code with a simple form, that its mean I don't make any economy to the memory, to understand the beginner how does the circuit its working.

An 8-pin Atmel ATtiny45 microcontroller uses one of its analog-to-digital pins to measure the voltage divided between a 4700 ohm fixed resistor in series with a BC Components 2322 640 66103 NTC 10 kilohm thermistor (Digi-Key BC1482 $0.68). The thermistor changes resistance in a predictable way based on the temperature.

The schematic show that the AccelR8 only uses 3 IC's. An AVR 8515 microcontroller do the calculation work and controls the other circuits. An MAX603 controls voltage and power-on/power-off. And the chip that makes it all possible, the ADXL202 from Analog Devices measures the acceleration.

A speedometer measures a wheel's rotational speed. Unlike conventional mechanical and moving-magnet designs that use analog moving-pointer displays, the electronic speedometer in this Design Idea features a digital readout and a power-saving device that uses few components. Figure 1 shows the digital speedometer's circuit design. An Atmel AVR AT90S2313 microcontroller, IC1, drives IC3, a 16-character, two-row LCD.

A pedometer is a device that counts the number of steps taken by a person and calculates the distance traveled by multiplying the number of steps by the length of the step. Here's a design solution for building a pedometer using the AVR MCU. The circuit not only combines all of the features of the traditional pedometer, it saves power (low power consumption is a must for a portable device) as well. The design also includes instantaneous speed measurement.

I designed a simple sinewave generator based on a Analog Devices AD9832 chip. It will generate a sinewave from 0.005 to 12 MHz in 0.005 Hz steps. That's pretty good, and definitely good enough for me ! But while waiting for the AD9832 chip to arrive, I came up with a very simple version of the DDS synth, using just the 2313 and a resistor network. It's controlled over RS232 from a small Windows program, and can generate Sine-, Sawtooth-, Trangle- and Sqare-waves ranging from 0.07 Hz to about 200-300 kHz in 0.07 Hz steps.

This is an experimental work to monitor a spectrum pattern of radio band, and is a continuous project from Audio Spectrum Monitor. To analyze the spectrum of an input signal, I chose an Atmel's AVR microcontroller used in Audio Spectrum Monitor to process FFT. When think it easy, it can be thought that sample an input RF signal directly and analyze it will do. However, you will able to recoginize that there are some techinical difficulties from following reasons.

Wine doesn't like subzero temperatures, and during wintertime, my "winecellar" got pretty cold. There was an electric heating element, but the thermostat was broken, so it was either full burn or nothing. That's how the temperature monitor/controller came to be. It was an obvious task for a small processor and I've always wanted to test the Dallas temperature sensors. So, I designed this little device which could monitor the temperature and control the heater.

To program some AVR microcontroller unit (MCU) you will need an AVR programmer. The better way to do that, is to buy some development kit like STK-500. This kit have the advandage to give you serial port, LCD connector, SRAM socket, 8 switches, 8 LEDs, connectrors for all of the ports of MCU and more, to one board. I sugest to beginers, to start working with STK 500 or some else developmert system, it will help them very much.

This is another project which fullfills a need. I once built a frequency counter using plain TTL chips. That was long before the CMOS HC versions, even before LS was available. It could measure up to 50 MHz and worked quite okay, but the TTL chips was extremely power hungry. I think there was about 20-25 TTL chips on that monster. Well, but the old counter is now somewhere in the shed, and as I now again needed a counter, I did a bit more modern design.

Atmel AVR µCs feature an enhanced RISC architecture that purportedly offer the highest MIPS-per-milliwatt capability in the 8-bit µC market. Figure 1 shows an easy-to-build AVR µC-programming circuit that can program the 40-pin AT90S4414/8515, the 20-pin AT90S1200/2313, and the eight-pin AT90S2323/2343. The programmer uses only three chips. It connects to the host PC's serial port via a MAX232 RS-232 transceiver, IC1. Power comes from a 9V wall cube and the 78L05 linear regulator, VR1.

I found the schematic of this programmer in my "AVR software and technical Library - April 2003" CD-rom and decide to publish it. The reason was, that this programmer is very stable and works perfect with AVR Studio 4. I have test it before publish it, with AT90s2313 and its worked fine!!! To work this programmer you must to connect a crystal 4MHz to slave device at the XTAL1 and XTAL2 pins, or if you have an device with internal oscillator (AT90S2343, ATmega161 etc) and its enabled , its not need any external oscillator.

A discussion recently on the mp3projects discussion board, about using DRAM memory with small 8-bit processors without DRAM controllers, got me to take up an old idea. I thought it should be possible to hook up a DRAM to a small processor (in this case an Atmel 8515), and handle the RAS/CAS sequencing and refresh in software. As DRAM is MUCH cheaper than SRAM, it would be possible to get a large (>500kB) memory at a reasonable price. There would obviously be a speed penalty, but in some cases, this would be of no importance.

The circuit is a simple, but accurate Digital Guitar Tuner. It samples the input, which can be directly from the mics of an electric guitar, or from a microphone, it you're using an acoustic guitar. It can ofcourse also be used for tuning other instruments. The samples are then checked against stored values for the strings, and the two LED's will show the tuning status - "Too Low", "Too High" or "In Tune" when both LED's are lit.