May 5, 2024

Zynq bootrom - boot modes

Everything you need to know is in the table on page 166 of the TRM. As it turns out, all you care about are 3 bits. These are the low 3 boot_modes bits, which are given on these pins: 
Boot_mode-2 == MIO-4
Boot_mode-1 == MIO-3
Boot_mode-0 == MIO-5
Who knows why it is in this crazy order, but it is. Inside the bootrom, a register is read, the lower 3 bits are masked off and that gives the boot_mode. There are thus 8 possible values: 
; 0 = JTAG
; 1 = Quad-SPI
; 2 = NOR
; 3 = UART (secret)
; 4 = NAND
; 5 = SD card
; 6 = ??
; 7 = ??
And it is as simple as that. Figure out what mode you want, translate that to the values you need to set on MIO pins via jumpers, then figure out how to do that on whatever piece of hardware you are dealing with.
Feedback? Questions? Drop me a line!

Tom's Computer Info / tom@mmto.org