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From: | Marcus D. Leech |
Subject: | Re: USRP, GPIO toggling and Gnuradio |
Date: | Fri, 10 Sep 2021 11:36:23 -0400 |
User-agent: | Mozilla/5.0 (X11; Linux x86_64; rv:78.0) Gecko/20100101 Thunderbird/78.13.0 |
Could you clarify--you WANT the pins to be switched at a very high rate--that is you expect your input signal to be switching between thresholds with a period smaller than 20us?Dear all,
I am currently trying to write an OOT block to switch a GPIO pin high or low depending on the input signal. So far it has worked with the configuration of the pins and I can also switch the pins according to the input signal in a relatively simple flowgraph consisting of a signal generator that produces a square wave signal.
The block's work function looks like this:
int GPIO_IO_impl::work(int noutput_items,gr_vector_const_void_star &input_items,gr_vector_void_star &output_items){
const float *in_signal = (const float *) input_items[0];
for(int i=0; i < noutput_items; i++) {if(in_signal[i] >= d_threshold){_dev->set_gpio_attr(gpio, std::string("OUT"), "HIGH", 0xffffffff)}
if(in_signal[i] < d_threshold){_dev->set_gpio_attr(gpio, std::string("OUT"), "LOW", 0xffffff);}boost::this_thread::sleep_for(boost::chrono::nanoseconds((unsigned long long)d_samp_period));
}
return noutput_items;}
The sleep function is important in that without it, regardless of the sampling rate of the square wave signal, the pin is switched with a period of 20us. If I use the sleep function, the whole thing works better, but only up to a sampling rate of about 20kHz. I have read a little bit about the function of the scheduler in GNURadio, but I did not find a solution.
Starting from the standing approach, I have tried using both Timed Commands and Boost Signals, with the result that the pins are switched completely asynchronously. Since I don't really know what to do at this point, I wanted to ask if any of you had experience with this kind of OOT block in GNURadio.
Best regards,
Anton
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