User manual

AT90USBKey Hardware User Guide 3-15
7627A–AVR–04/06
Section 3
Troubleshooting Guide
Figure 3-1 . Troubleshooting Guide
Problem Reason Solution
The Green “VCC-ON”
LED is not on
No power supply
Verify the power supply source (check
battery charge or USB connection).
AVRUSBKey does not
work
The AT90USB cannot be
programmed
The AVR JTAG ICE
probe is not
connected
Connect the JTAG ICE 10-PIN header to
the correct AVRUSBKey JTAG header
(page 13)
The memory lock bits
are programmed
Erase the memory before programming
with JTAG ICE.
The fuse bits are
wrongly programmed
Check the fuse bits with JTAG ICE
Can not connect to
USB bootloader
Force bootloader execution with HWB
under reset.
USB bootloader erased after a JTAG
debugging session: reprogram the USB
bootloader with JTAG.
AVR Studio does not
detect the AVR JTAG
ICE.
Serial/USB cable is
not connected, or
power is off
Connect serial cable to RS232 (STK500 -
AVR ISP) and check power connections
Connect serial cable to USB (JATG ICE
MKII, AVR ISPmkIIl) and check power
connections
PC COM port is in
use
Disable other programs that are using
PC COM port.
Change PC COM port
AVR Studio does not
detect COM port.
Disable COM port auto-detection in AVR
Studio file menu. Force COM port to
correct COM port