Hi Rathin! I didn't read all the stuff in the posts of this thread. But most of it seams irrelevant. Forget it.
You're using libpruio. That's the only way to reach your target --> That's OK. You cannot reach 20 kHz sampling rate due to two reasons: - you're using default step configuration. This is 183 cycles open delay and avaraging 4. That means 183 + 1 + 4 x 14 cycles for each sample (@ 24 MHz) = 10 kHz per channel. Therefor maximum sampling rate for 8 channels is 1.25 kHz. - you're using IO mode. The ARM CPU determines the sampling speed and your printf statement slows down the program execution, so you don't get the previous mentioned 1.25 kHz. In order to reach 20 kHz sampling rate you have to do 1. configure customized steps for fast sampling (ie. no open delay and no avaraging) 2. use either MM or RB mode to get accurate timing Either have a look at the triggers <http://users.freebasic-portal.de/tjf/Projekte/libpruio/doc/html/_cha_examples.html#SubSecExaTriggers> example (to use MM mode) or check out the following code (comming from an example named rb_file for next libpruio versions) /** \file rb_file.c \brief Example: fetch ADC samples in a ring buffer and save to file. This file contains an example on how to use the ring buffer mode of libpruio. A fixed step mask of AIN-0, AIN-1 and AIN-2 get configured for maximum speed, sampled in to the ring buffer and from there saved as raw data to some files. Licence: GPLv3 Copyright 2014-2015 by Thomas{ dOt ]Freiherr[ At ]gmx[ DoT }net Thanks for C code translation: Nils Kohrs <nils[ dot ]kohrs{ AT }gmail[ dOt ]com> Compile by: `gcc -Wall -o rb_file rb_file.c -lpruio -lprussdrv` \since 0.2.0.2 */ #include "unistd.h" #include "time.h" #include "stdio.h" #include "../c_include/pruio.h" //! The main function. int main(int argc, char **argv) { const uint32 tSamp = 123401; //!< The number of samples in the files (per step). const uint32 tmr = 5000; //!< The sampling rate in ns (5000 -> 200 kHz). const uint32 NoStep = 3; //!< The number of active steps (must match setStep calls and mask). const uint32 NoFile = 2; //!< The number of files to write. const char *NamFil = "output.%u"; //!< The output file names. struct timespec mSec; mSec.tv_nsec=1000000; pruIo *io = pruio_new(PRUIO_DEF_ACTIVE, 0x98, 0, 1); //! create new driver if (io->Errr){ printf("constructor failed (%s)\n", io->Errr); return 1;} do { if (pruio_adc_setStep(io, 9, 0, 0, 0, 0)){ // step 9, AIN-0 printf("step 9 configuration failed: (%s)\n", io->Errr); break;} if (pruio_adc_setStep(io,10, 1, 0, 0, 0)){ // step 10, AIN-1 printf("step 10 configuration failed: (%s)\n", io->Errr); break;} if (pruio_adc_setStep(io,11, 2, 0, 0, 0)){ // step 11, AIN-2 printf("step 11 configuration failed: (%s)\n", io->Errr); break;} uint32 mask = 7 << 9; //!< The active steps (9 to 11). uint32 tInd = tSamp * NoStep; //!< The maximum total index. uint32 half = ((io->ESize >> 2) / NoStep) * NoStep; //!< The maximum index of the half ring buffer. if (half > tInd){ half = tInd;} // adapt size for small files uint32 samp = (half << 1) / NoStep; //!< The number of samples (per step). if (pruio_config(io, samp, mask, tmr, 0)){ // configure driver printf("config failed (%s)\n", io->Errr); break;} if (pruio_rb_start(io)){ printf("rb_start failed (%s)\n", io->Errr); break;} uint16 *p0 = io->Adc->Value; //!< A pointer to the start of the ring buffer. uint16 *p1 = p0 + half; //!< A pointer to the middle of the ring buffer. uint32 n; //!< File counter. char fName[20]; for(n = 0; n < NoFile; n++){ sprintf(fName, NamFil, n); printf("Creating file %s\n", fName); FILE *oFile = fopen(fName, "wb"); uint32 i = 0; //!< Start index. while(i < tInd){ i += half; if(i > tInd){ // fetch the rest(no complete chunk) uint32 rest = tInd + half - i; uint32 iEnd = p1 >= p0 ? rest : rest + half; while(io->DRam[0] < iEnd) nanosleep(&mSec, NULL); printf(" writing samples %u-%u\n", tInd -rest, tInd-1); fwrite(p0, sizeof(uint16), rest, oFile); uint16 *swap = p0; p0 = p1; p1 = swap; } if(p1 > p0) while(io->DRam[0] < half) nanosleep(&mSec, NULL); else while(io->DRam[0] > half) nanosleep(&mSec, NULL); printf(" writing samples %u-%u\n", i-half, i-1); fwrite(p0, sizeof(uint16), half, oFile); uint16 *swap = p0; p0 = p1; p1 = swap; } fclose(oFile); printf("Finished file %s\n", fName); } } while(0); pruio_destroy(io); return 0; } Desription rb_file {#SubSecExaRbFile} ------- \Item{Description} This file contains an example on how to use the ring buffer mode of libpruio. A fixed step mask of AIN-0, AIN-1 and AIN-2 get configured for maximum speed, sampled in to the ring buffer and from there saved as raw data to some files. \Item{Preparation} No preparation is required. Optionaly you can customize the number of samples, the sampling rate or the number of samples in the source code and recompile your version. \Item{Operation} Start the program by `./rb_file` and you'll see console output like ~~~{.txt} Creating file output.0 writing samples 0-65534 writing samples 65535-131069 writing samples 131070-196604 writing samples 196605-262139 writing samples 262140-327674 writing samples 327675-370202 Finished file output.0 Creating file output.1 writing samples 0-65534 writing samples 65535-131069 writing samples 131070-196604 writing samples 196605-262139 writing samples 262140-327674 writing samples 327675-370202 Finished file output.1 ~~~ The program created two new files in the current folder, named output.0 and output.1. The files contain the raw data from the three ADC channels AIN-0 to AIN-2. \Item{Source Code} src/examples/rb_file.bas src/c_examples/rb_file.c BR -- For more options, visit http://beagleboard.org/discuss --- You received this message because you are subscribed to the Google Groups "BeagleBoard" group. To unsubscribe from this group and stop receiving emails from it, send an email to [email protected]. For more options, visit https://groups.google.com/d/optout.
