Hello,
I want to buy the JTAG from Olimex, but I’m a little bit confused about the compatibility with the AVR Butterfly board. Can I use the JTAG with this board?
Torsten
our AVR-JTAG takes power from target board
to the best of my knowledge AVR butterfly is small PCB with pill battery
I would not recommend this configuration unless you want to exchange the batteries every couple of hours
Tsvetan
Hello Olimex,
it’s possible to use an external power supply on the Butterfly. But the JTAG connector does not provide the power for the JTAG interface. Does the Olimex JTAG work without the power from the target board?
From the Butterfly user’s guide:
"The JTAG connector is used for the ATmega169 built in JTAG interface. The pinout of the connector is shown in Figure 3-9 and is compliant with the pin out of the JTAG ICE available from Atmel. Connecting a JTAG ICE to this connector allows On-chip Debugging of the ATmega169.
More information about the JTAG ICE and the On-chip Debugging can be found in the AVR JTAG ICE User Guide, which is available at the Atmel web site, www.atmel.com.
Note: Pin 7, NC(VCC) is the Vsupply pin for the JTAG. This pin is not connected because the JTAG would draw power from the battery on the AVR Butterfly."
Torsten
simplest solution is to connect pin.4 and pin.7 together and to power AVR buterfly from external power supply source
Tsvetan
Last question: The Butterfly works with voltages between 3.1 and 4.5 Volts. Does the JTAG interface support this voltages? I think I’ve read about only supporting 5 Volt targets.
Torsten
our JTAG have ATMega16 inside which according to datasheets works from 4.5-5.5V only
however all responses from our customers which try to work on 3.3V are positive
i.e. according to the datasheets it should not work, but it works
it’s OK to do some beginner’s code evaluation etc this way, but for for serious application we don’t recommend our JTAG to be used with 3.3V targets
we are developing new AVR-JTAG-L version which will work in 3.0-5.0 V range
Tsvetan