Credit Card Numbers - Visa. These Credit card numbers validate for Visa credit cards. The number and information is as real as it can be, and contains valid bin information. The structure of the credit card number starts with a valid bin number and also validates against the LUHN's formula.
UART is a protocol (Universal asynchronous receiver/transmitter ) for serial transfer of information. You ask about an embedded system with mentioning which so I'll assume that you have a block diagram with one indicating UART.
As a visual representation of data flow, flowcharts are useful in writing a program or algorithm and explaining it to others or collaborating with them on it. You can use a flowchart to spell out the logic behind a program before ever starting to code the automated process.