blhost using with un-programmed KL27

[leedavis]

How do I program the bootloader into a KL27 that is completely blank using the USB port.

[jeremyzhou]

Hi Lee Davis,

The KL27 has the on-chip ROM bootloader which supports the several of peripheral interfaces, of course, the USB interface is included.

So I'd highly recommend you to choose the the on-chip ROM bootloader to instead of the your own bootloader.
Have a great day,
Ping

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[leedavis]

Hi Jeremy,

I have been trying to boot from the internal ROM and then program via USB but I am having issues.

When I run blhost.ex it says it can’t find the device.

I know the KL27 Flash is blank so independent of the NMI pin on the processor it should run the boot state machine so I can see the device.

As far as the NMI pin, this pin is floating.

On the next board spin I will drive it low for a short time after RESET is de-asserted. Any idea how long I should drive NMI low to run the ROM boot?

I am also seeing the D+ pin on the KL27 at 3.3V. Note sure why this is the case. ???

Any ideas?

Thank you,

Lee

[bobpaddock]

View any installed/connected USB device on your system  via using this USBDEVIEW program.

It will show USB devices without having to run blhost.

Also try a different USB cable or a different port/hub.  I've run into both issues with USB devices in the past.

[jeremyzhou]

Hi Lee,

To force the MCU to the bootlader mode, we usually hold the NMI to low voltage at first, then reset the MCU later.

After following the procedure, the MCU will enter the bootloader mode automatically.
Have a great day,
Ping

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