SPI 12 BIT DAC INTERFACING WITH ARDUINO
MAX525 Quad 12-bit DAC with Arduino Nano
HC-05 BLUETOOTH MODULE
MHC-05 provides BT link though serial port of arduino nano for transferring data with PCs or Android devices.
It is even possible sketch uploading from Arduino IDE via Bluetooth using some tricks.
STM32 WITH ARDUINO IDE
Arduino ATmega 8-bit MCU boards have its limitations. Jumping to more powerfull processors is easy with the popular generic STM32F103 board nicknamed "bluepill" running at 72MHz and with 32-bit ARM architecture.
SD CARD READ/WRITE WITH ARDUINO
An introdution of file accessing using a SD Card module via SPI.
MIDI TESLA COIL CONTROLLER-INTERRUPTER
Several 328p in cascade connection using timers and interrupts generating on-off control signal to drive two tesla coils from MIDI input signal