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nachiket
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Registered: ‎10-07-2009

stdio with Microblaze over usb download cable

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Just out of curiosity, is it possible to do stdio with the Microblaze processor over the USB download cable without using RS232 cables? i.e xil_printf() could get redirected back over USB possibly via JTAG readback?
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nachiket
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Registered: ‎10-07-2009

Actually I stumbled upon some documentation that shows how to use MDM for redirecting xil_printf() back over programming USB cable. 

 

(1) The MDM module should be inserted with software debugging turned off.. simply enable the JTAG UART mode...

http://www.xilinx.com/support/documentation/sw_manuals/xilinx11/platform_studio/ps_p_dbg_sw_mb_enabling_debug_logic_jtag_uart.htm 

 

(2) And then start a jtaguart server on the host computer and setup a hyperterminal connection.

http://www.xilinx.com/support/documentation/sw_manuals/xilinx11/platform_studio/ps_p_dbg_sw_mb_starting_stdin_out_terminal_xmd.htm 

 

Although its relatively simple to setup, it can definitely use a dumber push-button flow (a tickbox to redirect stdio back the host CPU) that avoids the drama.

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pavithra
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Registered: ‎10-25-2009
hey i think rs232 terminal is used to display the input and outputs and usb cable is to download the code onto the fpga
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prateek_bhatt
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Registered: ‎08-21-2008

Hello.

Well thats quite possible but for that some homework has to be done from your side.

Xil_printf() directly uses the UART API to print some string.

If you want that to be done then you will have to write your own USB controller that can communicate with your PC and also on the PC side you will have to have one GUI of your own for receiving data from USB and printing it. 

Take note that by USB i mean to say a normal USB (FTDI or Cypress) and not some USB downloader for programming the FPGA with bitstream.

USB Downloader or normal JTAG are only meant for downloading bitstream and nothing else. 

Message Edited by prateek_bhatt on 12-30-2009 08:40 PM
Best of luck.
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Unlimited in my Limits.
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nachiket
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Registered: ‎10-07-2009

Thanks... I figured as much..

 

Not sure what would prevent us from reusing the same USB cable for both downloading bitstreams and UART IO. Probably the dev. board USB interface does not support multiplexing USB traffic back and forth.

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prateek_bhatt
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Registered: ‎08-21-2008

The hardware is such that it only recognizes .BIT files and none other.

The stuff you are talking about is present in ALTERA technology where with the same USB downloading cable you can download bitstreams and at the same time use it as std_in and std_out.

It supports USB traffic back and forth but its just that everything related to your FPGA can be uncovered.

Reading ID is a backward traffic whereas downloading bitstream if forward traffic. 

Best of luck.
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Unlimited in my Limits.
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nachiket
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Registered: ‎10-07-2009

Actually I stumbled upon some documentation that shows how to use MDM for redirecting xil_printf() back over programming USB cable. 

 

(1) The MDM module should be inserted with software debugging turned off.. simply enable the JTAG UART mode...

http://www.xilinx.com/support/documentation/sw_manuals/xilinx11/platform_studio/ps_p_dbg_sw_mb_enabling_debug_logic_jtag_uart.htm 

 

(2) And then start a jtaguart server on the host computer and setup a hyperterminal connection.

http://www.xilinx.com/support/documentation/sw_manuals/xilinx11/platform_studio/ps_p_dbg_sw_mb_starting_stdin_out_terminal_xmd.htm 

 

Although its relatively simple to setup, it can definitely use a dumber push-button flow (a tickbox to redirect stdio back the host CPU) that avoids the drama.

View solution in original post

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