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Altera_Forum
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16 years ago

Cyclone III not configuring

I have a 144 pin cyclone 3 that I'm trying to get working in a board design I've done. It is not configuring. I can see the TCK on the oscilloscope but no TDO data comes back from the FPGA. T...
Altera_Forum's avatar
Altera_Forum
Icon for Honored Contributor rankHonored Contributor
16 years ago

There is still no signal on TDO

I think the ground connection is good on the pad now. The board design is probably pretty bad. I have a double sided board so I think there are problems with ground return paths and digital and analog power isolation. I figured that I could still get it to configure even if I couldn't get performance at high frequency operation.

I posted the schematic. I have a jumper to control the VCCIO voltage between 2.5 and 3.3 V. I've tried to use both.

Do you know what the transition time is for the TCK for the JTAG circuitry? I've been trying to analyze it on my oscope. It seems to change frequency. I tried to trigger on over shoot but I only have a 50Mhz scope though so I might not be seeing everything correctly on those lines.

One more thought. I measured the power on rise time of the voltages and it was around 135 us. I know there are some comments about voltage rise time in the configuration documentation but I wasn't quite sure how this would affect the start up of the device.