MCU Boot Loader Troubleshooting
When MCU firmware load is interrupted, or the power-on firmware checksum test fails, the KX2 enters its bootstrap loader.
You can also
force the KX2 to enter its bootstrap loader
by turning the KX2 on with a 10-second press and hold of the two POWER buttons (RATE and A/B).
The MCU boot loader displays MCU LD on the KX2 front panel display.
The display may not be backlit.
To load KX2 firmware, follow these steps in sequence:
-
Turn your KX2 off by switching off or unplugging its power supply, including internal batteries.
The KX2's microcontroller may continue to run at very low voltage, and it must start from a power-on reset.
Disconnect any connectors that might provide power to the KX2.
A very small leakage current from another device might be enough to keep the MCU from completely resetting.
Wait 30-60 seconds before turning power back on.
-
If you are using a software sharing program such as
N8LP's LP-Bridge or microHAM's Router
between your personal computer and your KX2's serial port,
change the cabling so that the PC is connected directly to the KX2 without an intervening software "forwarder".
These programs send
K3 and KX2 Programmer's Reference
commands, and a KX2 in its bootstrap loader isn't able to process those commands.
Some commands may put the KX2 bootstrap loader into an unresponsive state.
-
Restart (reboot) the personal computer that will run the
KX2 Utility.
This isn't often necessary, but occasionally a serial port or USB device driver doesn't properly close.
Rebooting reinitializes the device and its driver.
-
Start the
KX2 Utility
and navigate to its
Port page.
-
Connect your KX2 to its power supply, then press and hold the
two KX2 power buttons (RATE and A/B) for 10 seconds, until you see
MCU LD
on the KX2 front panel display (without backlighting).
The red Tx light should be blinking.
Release the power buttons.
-
Click Test Communications.
This causes the initial poll to occur at 38,400 bit/s, which matches the RS-232 speed of a K3 in its bootstrap loader (MCU LD).
You should see a dialog that looks something like this:
The
KX2 Utility
cannot load firmware if it does not receive responses.
Information in
USB to Serial Adapter Troubleshooting may help to resolve this issue.
The problem might be serial port cabling, an incorrect COM port choice, a problem with the Personal Computer,
or a damaged KX2 serial port.
Incorrect COM port choice is a very common problem.
Sometimes USB to Serial Adapter device drivers change the COM port number unexpectedly.
Some devices, such as internal modems, may respond similarly to a KX2 in its boot loader.
- When you see this dialog, press its OK button to continue.
-
Firmware load can take quite a long time if the View Menu
Trace
menu item is checked.
Uncheck Trace unless you require this diagnostic information.
-
Select the
Firmware
tab, and click
Send All New Firmware to KX2.
If the send buttons are disabled, view
Troubleshooting: Send Buttons Disabled.
-
The
KX2 Utility
should send MCU firmware to your KX2, followed by the DSP if it is newer than the installed DSP firmware revision.