Arty A7 Microblaze Reset

[Stephen D]

Hi All,

have been making great progress with my project. It's based on the "Arty - Getting started with Microblaze" tutorial.

Something I've noticed is that the RESET button doesn't seem to actually reset the processor, i.e pressing RESET doesn't result in the startup message being sent to the console for the 'Hello World' example.

I've tried wiring an LED into the block design at various points but it seems like the 'reset' port created from the board file (C.0) isn't actually connected to the button.

The tutorial has 'reset' connected to both the clocking wizard and the MIG. The MIG output 'ui_clk_sync_rst' autowired to the Processor System Reset block 'ext_reset_in' pin. Have tried reading the MIG docs but don't understand why this routing is required.

I tried starting with a new project and block design and dragging the 'System Reset' component onto the canvas. Doing this creates a 'reset' port connected to a Processor System Reset IP, pin 'ext_reset_in'. Presumably this is the 'preferred ip' connection, but it differs from the tutorial.

Can anybody please explain?

Thanks,

Stephen

[jpeyron]

Hi @Stephen D,

My understanding is that the reset wipes all program data. You would need to use flash to have the program work after a processor reset. Here and here are 2 tutorials for monogramming the quad spi flash. The first shows how to do this from Vivado and the second tutorial shows how to do this from SDK.

cheers,

Jon

[jpeyron]

Hi @Stephen D,

The reference manual here under section 9 Basic I/O  and in section 8 USB-UART Bridge (Serial Port) discusses the different things the reset button will do depending on what JP2 is set to. Is the ck_rst shorted?

thank you,

Jon  

[Stephen D]

Hi Jon,

yes, JP2 is shorted.

I am wrong about the reset signal, the button is definitely connecting properly and I get various signals (active high/low) as I work through the circuit. The mb_reset signal is a narrow pulse and not easily visible on a LED in bright light.

So the processor is getting a reset signal. Why does program execution not start from the beginning? Has the downloaded program been wiped?

Regards,

Stephen

[Fawaz]

Hello,

I am seeing similar behavior when running Microblaze from MIG. After reset, the MB resumes the execution, its not restarting from beginning.

something like this:

 

print("Hello\n\r");

while(1){

print("byeeee\n\r");

}

 

So after reset, the terminal is showing only byeeee, its not printing Hello unless I re-download the elf to see hello msg again.

 

When I run from BRAM, everything is working perfectly as expected.

 

Any Idea what would be the issue?

 

Thank you