The firmware works for SD or SDHC cards only, 1-32 GB. ATtiny85 or ATtiny45 can be used.
The FAT32 code is minimal, it only fined the files location and repeats playing all the songs in the order they are in the file allocation table. File names have to be short, 5 characters max, and located in the root folder.
TIMER1 set as PWM is used as a DAC to convert the digital data to audio. The sound is tape quality. The STOP pushbutton resets the ATtiny.
SD card interfaces in SPI mode. Reading the data is in multi-blocks.
ATtiny is programmed using Arduino IDE and Arduino as ISP. Use these instructions https://gist.github.com/ij96/804e731bd31dbb95b2b043e93c79ceab with the difference of burning bootloader with setting "Clock Source 16MHz (PLL)". When using Arduino as ISP unplug the SD card while loading the sketch to avoid 5V signals to the SD card.
SD card can tolerate 3.7V max, circuit can be powered by 3.3V including 3.7V from lithium cell.
TO SET UP THE CARD:
Format the card with FAT32.
Create sound files type .wav
Name the files with short names, 5 low case characters max + wav, ie "12.wav".
Save the files as 22.050KHz, 8 bits, mono.
Add the files to the root directory of the card (don't use a subdirectory).
The circuit is for SD card for micro SD card use a converter from SD to micro SD.
The FAT32 code is minimal, it only fined the files location and repeats playing all the songs in the order they are in the file allocation table. File names have to be short, 5 characters max, and located in the root folder.
TIMER1 set as PWM is used as a DAC to convert the digital data to audio. The sound is tape quality. The STOP pushbutton resets the ATtiny.
SD card interfaces in SPI mode. Reading the data is in multi-blocks.
ATtiny is programmed using Arduino IDE and Arduino as ISP. Use these instructions https://gist.github.com/ij96/804e731bd31dbb95b2b043e93c79ceab with the difference of burning bootloader with setting "Clock Source 16MHz (PLL)". When using Arduino as ISP unplug the SD card while loading the sketch to avoid 5V signals to the SD card.
SD card can tolerate 3.7V max, circuit can be powered by 3.3V including 3.7V from lithium cell.
TO SET UP THE CARD:
Format the card with FAT32.
Create sound files type .wav
Name the files with short names, 5 low case characters max + wav, ie "12.wav".
Save the files as 22.050KHz, 8 bits, mono.
Add the files to the root directory of the card (don't use a subdirectory).
The circuit is for SD card for micro SD card use a converter from SD to micro SD.
