Atmel XMEGA-A1 Xplained Evaluation Board ATAVRXPLAIN ATAVRXPLAIN Data Sheet

 

8370C-AVR-12/11 

The output range of the light sensor is 0V – 3.3V. The ADC reference must therefore 
be high enough to match the output range of the light sensor when performing 
measurements. 

Touching the test points of the USB data lines on the reverse side of the board while 
there is an ongoing communication, might interrupt the device and cause the device 
to stop responding. The kit must be reconnected to start working properly again. 

Because JTAG_TDO and PDI_DATA are connected on the PCB for this kit, JTAG 
must be disabled on the device in order to use PDI. The reason for this is that when 
JTAG is enabled it will enable a pull-up internally on TDO which interferes with the 
PDI initialization sequence. 

The connection of JTAG_TDO with PDI_DATA is also an issue when the application 
on the device uses the JTAG_TDO pin e.g. by driving this pin actively or by using a 
pull-up. This will interfere with ongoing PDI communication. Additionally, when JTAG 
is disabled and the application is driving the JTAG_TDO pin it might even not be 
possible to establish a PDI connection. A workaround for this is to add a ~1k resistor 
from PDI_CLK/RESET to GND. This will keep the device in reset while PDI is 
enabled. When a PDI connection is established the flash can be erased or JTAG can 
be enabled in order to "unlock" the kit.