-1
\$\begingroup\$

I recently got myself FRDM K64F board and got myself occupied with the following questions:

  • Does the compiled hex code i send to my board has to go to the UART chip prior going into microcontroller?
  • And if I want to output some text back to the computer using a terminal program like PuTTY, why does computer see my Board as a COM port even though my connection cable is USB?

Any detailed answer is much appreciated :) Have a nice day people .

\$\endgroup\$
1
\$\begingroup\$

Like many other development platforms, the Freedom series development boards contain not one, but two micro controllers.

The "named" one is the "target" micro controller on which your program runs.

However, the other one is a programmer/debug interface which allows you to load programs to the target over a USB interface, taking the data from the host PC (often written to a fake mass storage drive) and injecting it via the target processor's SWD interface. As an additional function, it present a serial-like CDC interface to the host, which proxies signals to and from one of the target's UARTs, which can be rather useful for debug output and simple data transfer.

\$\endgroup\$
2
\$\begingroup\$

One of the standard features of USB is that a peripheral can present itself as a CDC (Communication Device Class?) device. On the OSes I know the OS will present such a device to the user and application programs as a (Virtual) serial port.

\$\endgroup\$
0
\$\begingroup\$

The one reason for seeing your connection as COM is usage of RS232 protocol which is the easiest way of serial communication between your PC and MCU (UART). It can be made so your PC sees dev. board as USB device but that involves much more complicated software for programming and much more capable programming MCU. Your board has 2 parts. One part is MCU with all peripheral "devices" required to work properly and the other part is the other MCU (already programmed by manufacturer) for "programming" and "debugging" of your HEX code. In many cases (depends on manufacturer), you can send data from your main MCU to the PC via the corresponding UART that is connected to the programming MCU.

\$\endgroup\$
  • 1
    \$\begingroup\$ RS232 is a voltage and pin standard not a protocol. \$\endgroup\$ – old_timer May 30 '16 at 23:00

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Not the answer you're looking for? Browse other questions tagged or ask your own question.