I'm trying to get a proper log of the SD protocol packets exchanged between an SD card and its host interface while it initializes to DDR200 mode.
For this purpose I have 2 seemingly suitable logic analyzers: the 'cheap' $400 DSLogic U3Pro32 and the ZeroPlus LAP-C Pro 16064M (~€1000).
When I hook up the ZeroPlus, the SD card does not initialize properly. If I leave the probe wires connected but remove the connector block from the LA, card initializes fine. Input impedance is listed as 500 kΩ / 10 pF but I must admit I lack the background to understand its implication. The wires are left as short as possible, and I used the shortest probe wires that came with it. This block consists of 8 inputs, 1x GND and 1 clock wire.
Next I tried hooking up the DSLogic and although the wires it came with are over twice as long, the SD card initializes perfectly fine and I can sustain file transfers at >140MB/s while it is connected. It must be noted that these inputs are all accompanied by a GND wire, though I connected only 3 of them. Is that what makes all the difference? Is there something I could do to preven the signal integrity degrading when connected to the zeroplus?
Fwiw, reason I'd very much like to use the ZP software is because of their protocol analyzers. The DSview software that came with the DSLogic is amazing for acquisition, super fast, mega responsive and seemingly stable. The zeroplus software on the other hand feels sluggish, is highly 'themed', occasionally crashes, tends to lose settings, and after acquisition completes it can take a lot of time to transfer the data to the software over USB. The USB3 interface doesn't go much faster than 55MB/s during this. Then the protocol analysis takes another while, during which it is prone to crash. But when all goes well, the result is amazing and analyzing captures with their protocol analyzers works superb. The SD protocol analyzer with DSview on the other hand doesn't process the data lines, doesn't provide a packet list, and makes it incredibly difficult to sort through the data.