[Hackrf-dev] How to do retunes in firmware ?

[Patrick Sathyanathan]

Hi Dominic,
 
Thanks for the info. I have been looking at the firmware code in .../hackrf/firmware/hackrf_usb and I see there is a "main" function in hackrf_usb.c. I'm not sure I understand the control-flow. After doing some initialization there seems to be a loop transferring buffers 0/1. Is this loop where I should insert my periodic retuning code ?
 
Is there a document that outlines the design of the firmware ? Something that outlines the major modules and that could point me to where I need to make my modifications  ?
 
Thanks,
 
--Patrick
 
From: dominicgs at gmail.com
Date: Sat, 9 Jul 2016 14:05:47 +0100
Subject: Re: [Hackrf-dev] How to do retunes in firmware ?
To: wpats at hotmail.com
CC: hackrf-dev at greatscottgadgets.com

On 8 July 2016 at 03:02, Patrick Sathyanathan <wpats at hotmail.com> wrote:
>  
> I am trying to use the HackRF-One for fast scanning somewhat like osmocom_spectrum_sense but using the hackRF library directly. I want to reduce retune time as much as possible. A recent thread on this list mentioned that firmware tuning is the fastest. How do I implement periodic (at fixed intervals) retuning in firmware ? Can I also make my PC application aware of the current frequency at any time with this ?

The firmware doesn't currently support retuning, so the feature would need to be added.  You would need to determine a way for the host application to know what the frequency is, I would suggest either:
1) putting the currently tuned frequency at the start of the buffer to be sent back to the host
or
2) configuring a fixed number of buffers to return to the host between retuning event

The first means changing the buffer sizes and any complexities involved with that, the second means synchonisation issues if a transfer is dropped for any reason

> Is there any sample code I can look at ?

I believe that Mike Walters is currently working on a project with very similar goals.  I don't know if his code is available yet, but I would expect it to appear on GitHub when it is.

Dominic
 		 	   		  
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