LPSCI - how does it function on FRDM-KL25Z

[nelsonlobo]

Hi,

As per what i have noticed from FRDM-KL25Z_SCH_REV_E shematics UART0_RX/TX of KL25Z is connected to UART1RX/TX of K20 i.e. the OpenSDA Debugger in this case.

Lets consider the following case:

1. Ive designed a standalone KL25Z board without any debugger but only with header for debugging/programming and other GPIOs

2. Debugged/Programmed using K20 available on FRDM-KL25Z

Problem:

If i were to use the LPSCI polling example for frdm-kl25z would it work for my standalone KL25z board, if "yes" how would its interface be designed to the USB port.

Regards,

Nelson

[Jorge_Gonzalez]

Hello Nelson Lobo:

Basically the OpenSDA interface (K20) acts as a UART to USB CDC bridge. It means that the KL25 sends data to K20 using UART0 TX pin as you noticed, but such data is then mounted over a USB CDC class firmware in the K20 and sent to the PC; or the other way around, the K20 receives data from the PC over USB CDC class and translates that information to raw UART data for the KL25 (RX pin).

If your custom board does not integrate OpenSDA then to use the same project you need to implement such bridge somehow. For example you can use the USB2SER Freescale board.

Another option if you want to interface the KL25 to the PC directly using USB module then you can integrate the USB CDC device class in the KL25 itself. There are example projects in KSDK installation:

C:\Freescale\KSDK_1.2.0\examples\frdmkl25z\demo_apps\usb\device\cdc\virtual_com\bm

I hope this helps to clarify.

Regards!,
Jorge Gonzalez

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[nelsonlobo]

Hi Jorge,

As per your suggestion I programmed my FRDM-KL25Z board with C:\Freescale\KSDK_1.2.0\examples\frdmkl25z\demo_apps\usb\device\cdc\virtual_com\bm but due to lack of documentation as i referred to KSDK 1.2.0 DemoAppUserGuide, Im unable to figure out what am i supposed to do next. Im assuming to connect the USB cable to port marked as KL25Z for this app. Just sceptical that i may fuse up something, so please suggest.

Regards,

Nelson Lobo

[Jorge_Gonzalez · Accepted solution]

Hello Nelson:

Yes, to try the demo just connect the USB port of FRDM-KL25 (the one marked as KL25Z USB) to a USB port in your PC. It should enumerate as Virtual COM. Open a terminal software to connect to such port and type any characters. You will see the characters echoed to the terminal.

When in doubt each USB demo has a readme file. In this case the path for the file is the next:

C:\Freescale\KSDK_1.2.0\examples\frdmkl25z\demo_apps\usb\device\cdc\virtual_com\readme.pdf

Let me know if you have issues.

Regards!

Jorge Gonzalez