May 5, 2024
Zynq bootrom - boot jumpers on the Zybo and Zedboard
Both the Zybo and Zedboard have the uart connected to MIO-48
and MIO-49 (unlike the Ebaz which has it on MIO-24 and MIO-25).
This means that if you are interested in the secret UART mode, you
are good to go with either of these boards in that regard.
Zedboard
Here you have jumpers for MIO-2 through MIO-6, so setting the values
you need on MIO-3, MIO-4, and MIO-5 is childs play.
Zybo
We have the uart on the right pins (MIO-48 and MIO-49), but there is a stupid
arrangement for the bootmode pins. A 4 pin header has been designed that
lets you select one of 3 modes (SD card, Q-SPI, or JTAG) by giving access
to MIO-4 and MIO-5 on this header. MIO-3 is permanently connected to ground
via a 20K resistor.
If you were hell bent to play with the secret UART, you could touch a Vcc
wire to the non-ground side of this resistor during boot (the pins are
only sampled during boot) -- but there are easier ways using other
hardware.
S9 Antminer
Here we have it easy (as we do with the Zedboard). We have the uart on
MIO-48 and MIO-49 and easy to understand jumpers for all three boot mode pins.
So, if you have one of these, this is an easy path.
Feedback? Questions?
Drop me a line!
Tom's Computer Info / tom@mmto.org