Due to the PicoZed eMMC speed issues, we have been doing some additional testing. We have found that the mux that allows the user to select between PS MIO going to the JX connector or using the eMMC was affecting the performance. When the mux is removed and hard-wired across the pads to connect the eMMC, previously failing eMMC circuits will pass at cold temperatures running at 50 MHz in x4 mode.
We are considering a PCB revision to PicoZed that will replace the mux with resistor jumpers. The resistors would be set to select the eMMC. If someone wanted to use the PS MIO on the JX connector instead, they would have to request a special version that had the resistors populated in the other position.
If you are designing PicoZed into your product and using the PS MIO[9:15] through the JX connector on your carrier, will you please contact me with the challenges this may present? You are welcome to reply in this forum or private message me.