FRDM-K22F board show no virtual serial port and stuck on bootloader mode

[RohitKewatLFT]

Hello,

I encountered an issue with my FRDM-K22F development board. After connecting the board to my Windows 10 system, it only shows as "mbed Serial Port (COM3)" in Device Manager. According to the user guide, it should also appear as a virtual serial port, but it does not. This prevents me from updating the CDC driver and running the quick demo using Tera Term. Initially, the RGB LED glows green.

I believe this problem can be resolved by updating the firmware (OpenSDA v2.1) using the drag-and-drop method. However, the board is now stuck in bootloader mode, displaying a "BOOTLOADER" drive in File Explorer. Despite attempting the following steps, it remains in bootloader mode:

1. Long press (2 seconds) the reset button.
2. Disconnect and reconnect the USB cable to power cycle the board.

The RGB LED no longer glows in bootloader mode.

I have attached the quick user guide and a screenshot of File Explorer. I am currently unable to provide a photo of Device Manager in normal mode, as the board is stuck in bootloader mode and only shows as "Portable device -> BOOTLOADER."

What I need assistance with:

1. How to exit bootloader mode and return to application (normal) mode.
2. How to enable the virtual serial port in Device Manager and update the CDC driver.

Thank you for your help.

[ErichStyger]

The K22 is using the same OpenSDA v2.x as on the K64, so you could check out this: https://mcuoneclipse.com/2016/06/26/how-to-recover-the-opensda-v2-x-bootloader/ with downloading the firmware file from ttp://www.nxp.com/opensda 

If you have an old board with an old bootloader, you have to update the bootloader first.

See https://mcuoneclipse.com/2014/11/01/illustrated-step-by-step-instructions-updating-the-freescale-fre...

[xiangjun_rong]

Hi,

On the device manager of PC, it shows as "mbed Serial Port (COM3)", the COM3 is the virtual COM port of KE02, if you connect a Putty, and set baud rate as 15200, can you see any output?

If you want to change the firmware of the probe, pls follow up the process:

https://www.nxp.com/design/design-center/software/sensor-toolbox/opensda-serial-and-debug-adapter:OP...

If you want for OpenSDA enters bootloader mode, It is used to place the OpenSDA circuit into Bootloader mode by holding down the RESET pushbutton while plugging the USB cable to USB connector J6. Once the OpenSDA enters bootloader mode, other OpenSDA applications such as debug application can be programmed.

Hope it can help you

BR

XiangJun Rong

[RohitKewatLFT]

Hi,

Thank you for your response. Here are my observations:

1. The baud rate should be 115200, not 15200. I did not receive any response in Tera Term when using this setting.
2. The board is already in bootloader mode. I need assistance on how to exit bootloader mode and return the board to normal mode.

Thank you for your help.