FTDI

UART to RS232 to FTDI
USB - [FTDI] - RS323 - [UART] - 8 Bit Parallel

"A UART converts serial RS232 data into 8 bit parallel data. Technically the term is a little more generic than that specific use but that's what 99% of them are used for.

FTDI is a brand name for a company that make USB chips. Their most common chip is an RS232 to USB converter but they also make other USB interface chips. Since USB is serial (Universal Serial Bus, it was originally designed as a replacement for RS232) a conversion from RS232 to USB is a serial to serial conversion.

When you connect to the development board your computer uses USB to talk to the FTDI chip which converts that into RS232 which then connects to the ATMEGA microcontroller.

The reason why things like microcontrollers still use RS232 rather than USB is that it is far simpler to use, you don't need drivers or have to worry about who is the host and who is the master and a UART is a simple enough piece of logic to include in the micro. Basically if you are keeping things simple then RS232 is all you need. However computers don't often have RS232 ports these days and so development boards often include parts like the FTDI USB-RS232 device to make it easier to connect a computer." --https://answers.yahoo.com/question/index?qid=20111219121807AA67lBg

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"What is the difference between an FTDI chip and a UART? To my knowledge the FTDI chip converts RS-232 serial data into USB form (to go into a com port). Also, the UART is setup that converts parallel data into serial data. Where I get confused is I know that the computer reads bytes (thus parallel bits) so you would need a UART to convert any serial."

keywords
FTDI UART RS232 Serial