Turn-key PCB assembly services in prototype quantities or low-volume to mid-volume production runs

Attiny85 driven music card player

Music cards are not something new. But those that you normally get play annoying tunes that are low quality. Dmitry thought that he can do better. So he started building his own version of music card. His goals were to have full fidelity playback, random songs each time and be small enough to mimic gift card. To accomplish this he had to solve several problems like playing quality sound with Attiny85 microcontroller. It seems that he’s done this pretty well by generating 64MHz on one timer with PLL which his used to generate PWM based analog output. Another 32KHz timer generated actual music sampling. Music has to be stored in SD card in WAV format. Then they are picked by using uFAT library. Another issue were music volume. Since Attiny85 could source up to 20mA with 3.0V battery is could provide about 60mW power which is really low. One option could be adding power amplifier, but since signal is digital, he ended up with using full bridge driver out of four MOSFETs. This way he was able to reach 5.8W… Continue reading

Tiny SD music player

Probably it is a smallest SD music player in the world based on AtinyX5 microcontroller series. Its size actually is limited to SD card which sits on back of PCB. Microcontroller generates sound with PWM that can be driven to speakers directly. AVR tiny microcontrollers have very little RAM so handling FAT file system is quite a task. There is a Petit-TatFs module used which is developed for small memory systems with less than 512 bytes. SD music player is able to play wave files 8/16-bit mono and stereo at up to 48kHz sampling rate. I is really cheap solution to add in to gifts, toys and anywhere where small size and simplicity is required. Continue reading