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QTC-UMD / dds-sweeper

Raspberry Pi Pico interface for the AD9959 DDS
BSD 2-Clause "Simplified" License
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Sweeping all 4 channels #11

Closed ehuegler closed 2 years ago

ehuegler commented 2 years ago

Triggering an up sweep on all 4 channels at once seems to break everything.

I had an issue earlier where the reset pin on the AD9959 was connected to an output pin on the pico which was next to the 4 profile lines, and I think the cross talk was enough to put the reset line high when the profile pins went high. This should no longer be the case since I have moved the reset line, and the issue seems to persist even if I remove the reset line from the pico and tie the reset pin on the AAD9959 directly to ground.

dihm commented 2 years ago

This feels like it may be a power issue (ie the board draws more current than the power supply provides, causing a failure mode that resets things). You may want to consider powering off a benchtop DC supply sooner rather than later to see if that is the issue. There is a free Keysight triple DC supply in the other lab (that I normally sit in) on the shelves along the front wall.

ehuegler commented 2 years ago

I setup the power supply, but I have not spent more time on this issue yet. I did notice that when it occurs the current draw of the AD9959 drops from ~12mA to ~3mA.

ehuegler commented 2 years ago

It seems like it may have still been an issue with the pico, but I was not able to figure out exactly what was going on, so I got rid of the reset line entirely. The AD9959 has another pin that can be used for syncing, so it is not completely necessary. sweep-showcase . Independent sweeps on all 4 channels works now.

dihm commented 2 years ago

This is a super cool picture! We are going to have to come up with some super pretty looking demo to set up that demonstrates this thing in all its glory.