Hardware Things

Boot-Loading the ATMEGA 328P

ATMEGA 328P is the heart of Arduino Board. We can modify the design of the Arduino in fact better compared to commercial Arduino in the market by including all the best practices to eliminate the switching noise and best layout practices.

ATMEGA 328P as a DIP is brain dead so we have to Boot-load it with a firmware which makes it work like actual Arduino. 

Details 

Communication Protocols

Electronic devices talk to each other by sending bits of data through wires physically connected between devices.  The bits of data can be transmitted either in parallel or serial form. In parallel communication, the bits of data are sent all at the same time, each through a separate wire.  In serial communication, the bits are sent one by one through a single wire.  

Here we understand more about Serial Communication protocols.

Serial Peripheral Interface (SPI) -  Description

Universal Asynchronous Receiver/Transmitter (UART) - Description

Inter-Integrated Circuit (I2C)- Description  Pull-up resistor concept - In-Depth understanding

                                                                    Sparkfun_I2C