This is amazing frequency counter project. It’s construction is very simple but has a great use. High frequencies are more important for radio amateur who are dealing with radio transmitters and receivers. This frequency counter have ability to subtract the incoming frequency by offset(10.7MHz or 455kHz), so Intermediate Frequency of oscillator could be seen.

As this frequency counter is built under PIC16F870, it can’t measure high frequencies directly especially with high accuracy. Frequency is captured via frequency divider LMX2322 which divides by 64. Frequency counter has optional RS232 output what enables to output frequency value to PC screen or other devices. You can download all project files necessary from original page including two firmware versions 999MHz with 1kHz step and 2.5GHz with 10kHz step.

While searching for information on how Chris invested some time and developed a simple VGA tester on PIC18F452 microcontroller. Device is capable to output simple figures and text to VGA monitor. It is possible to select one of RGB colors one at the time with simple switch.

Circuit of VGA tester is very simple because VGA signal is a digital signal, no additional circuitry is needed. As timing on generation of VGA signals is essential, there is external 4MHz crystal used, and all programming is done in low level assembly language. Microcontroller clock speed is slow, only 26×480px resolution can be generated. Possible improvements as author says are: resolution increase by increasing clock speed and color intensity regulation with DAC. But lets be simple – it is perfect VGA monitor tester that fits in to the pocket.

Moving along the Philips ARM Design Contest 2005 projects list there is another interesting project you may find interesting. Its a flash card audio player which plays lossless audio tracks directly from MMC flash card. Interesting thing is that player is controlled by car audio head-end unit.

The idea was to emulate a CD changer so the head-end could be adopted to communicate with player. Instead playing CD tracks player changes the tracks in subdirectories. Each subdirectory appears as different CD to head-end unit. Other commands like play, stop, next CD, next track are normally supported. Audio signal is converted do analog through external high speed stereo DAC. Signal is sent back ti head-end unit for amplification after when music reaches speakers. Nice project probably more for learning purposes rather than practical. Download files here.

This project is developed by Bernard Debbasch and is a winner in Philips design contest 2005. it is really cool and flexible answering machine which allows many things including Media storage, internet access where messages can be sent in form of SMS or e-mails, interfacing to phone line, DSP routines. Answering machine(TAM-TAM) also supports multiuser interface where up to four users can have custom settings.

The whole machine is built around LPC2138 ARM7 RISC microcontroller. Project gives a good demonstration of DSP functions including FSK demodulation, voice playback and record, DTMF tone generation and detection. Concurrently there are also running IP stack and File system management tasks. And still, whole system gives good level of performance. Code blocks are written so that they may be easy reused in other projects. All project files are available for download.

KapteinKUK have modified his wall clock by adding 12 LEDs controlled by ATtiny2313 microcontroller. LEDs are flashing randomly driven patterns with some variable intensity driven by PWM channel.

Download asm code and circuit here. Dont forget to set internal clock to 1MHz. Nice toy for Christmas rush.