AVR-JTAG (serial)/Olimex Atmega128 problem... (not working)

Development Boards MicroMod
1

Hello Everyone,

I’m having trouble using the JTAG interface on my Atmega128. I have purchased the Olimex Atmega128 breakout board and the AVR-JTAG adapter. The AVR works fine and I can interact with it via an ICSP connector and PonyProg, however, when I load up AVR Studio and try to connect via JTAG I get nothing. I checked the fuse settings in PonyProg and JTAGEN is checked.

The JTAG connector’s red led doesn’t come on when I power up my circuit. Is there a possibility it is dead?

Help is greatly appreciated…

**EDIT: I checked the power on pins 4 & 7 (VCC) and they read about 2.74v so I do not think it is a power issue.

Someone, anybody? I sent Sparkfun an email monday and a phone call today and I haven’t heard a thing back…

2

what is your power supply voltage?

Tsvetan

3

I’m using the sparkfun breadboard power supply @ 5v.

http://www.sparkfun.com/commerce/produc … cts_id=114

I haven’t taken measurements, but the info on that page says it will supply up to 1.5A, more than enough for the atmega128 and the JTAG, isn’t it?

4

if your power supply is 5V why do you measure 2.7V on Vcc?

Tsvetan

5

I’m using the sparkfun header board for the Atmega128, the transistor reads

H

78L05

3F

…and it outputs only 2.96v? (measured off the EPWR jumper) even though there is 5v coming into the board itself (measured off the +/- pins)

6

The 7805 regulator needs at least 7V on its input to make +5. Since there is a series diode before the regulator (another 0.7V drop), feed in at least 8V on the “power” connector.

You can also remove the “EPWR” jumper (disconnecting the regulator) and feed 5V in thru pin 1 of the EPWR jumper.

7

I spoke with sparkfun. They pointed out the above.

duh!

Leaving here for others to hopefully not repeat my stupid mistake. :slight_smile: