I have a MicroZed and use the jumper to let it boot from SD. MicroZed configures to use MIO40-45 but how does the Zynq knows it is 40-45 before it loads FSBL from SD?
Does it look through all SD possible connections to see where SD card is there and to see whether the file is in the SD card? So what if I have two SD slots does it mean it will use the first FSBL it finds? Regards,
The Zynq device, as detailed in the Zynq Technical Reference Manual, chapter 6 ( http://www.xilinx.com/support/documentation/user_guides/ug585-Zynq-7000-TRM.pdf ) reads the mode pins at boot time and selects one of five predetermined boot devices: NOR, NAND, Quad-SPI, SD Card, or JTAG.
The MicroZed implements three of these options: QSPI, SD Card, and JTAG. Take a look at the MicroZed HW Users Guide for details:
http://zedboard.org/support/documentation/1519
The SD Card interface on the MicroZed is implemented on the default MIO pins so that the Zynq knows where to access and boot from. You can implement an additional SD Card interface using the MicroZed expansion connectors but the primary boot device must be either the QSPI Flash, the default SD Card interface, or the JTAG interface as determined by the configuration mode jumpers.
You could use a secondary SD Card interface as a secondary boot device if your FSBL code were to configure it and start a Second Stage Boot Loader.
You might want to take a look at the Avnet Zynq SW and HW Speedway workshop material, it will give you a detailed description of the Zynq internals. There are also hands on labs that target the ZedBoard and the MicroZed.
Developing Zynq
-7000 All Programmable SoC Software (Vivado 2013.3 and 2014.4.1)
Developing Zynq-7000 All Programmable SoC Hardware (Vivado 2013.3 and 2014.4.1)
-Gary
