Can somebody explain, why it increases the size so much? I have a rough idea, but would be nice to get an explanation :)
Am 2019-08-04 15:38, schrieb Alexandre Abadie: > Hi Oliver, > > See my answer about printf below. I'm not enough expert with timer accuracy > but there are known issues with xtimer, maybe have a look at related > issues/PRs on github ? > > ----- Le 31 Juil 19, à 15:02, oliver [email protected] a écrit : > >> 1 Question: >> >> I try to calculate some floating point digits on the SAMR21-xpro Board. >> When I print the floating point digit it shows me nothing. >> >> My Code: >> ================================================================= >> uint32_t time_diff = 554; >> >> double distance = (33./2000.) * time_diff; >> printf("distance = %f cm\n",distance); >> ================================================================= >> >> Output: >> ================================================= >> 2019-07-31 14:36:58,631 - INFO # distance = cm >> ================================================= >> >> Stack Overflow [1] tells me that floating point are disabled by default >> on arm-gcc. >> Whats the trick ?? >> What should I add to the Makefile ? > > Just add USEMODULE += printf_float to your application Makefile. > Note that this will noticeably increase the generated firmware size. > > Alex > >> 2. Question: >> >> If I try to print (using printf) uint64_t variables I have the some >> problem as above. >> >> 3. Question: >> >> How precise is the current system time on RIOT ?? >> I set a GPIO HIGH and LOW with a time difference of 100 and less >> microseconds. Before I set the GPIO HIGH and LOW, I call function [2]. >> If I compare the time with an oscilloscope I get horrible deviations. >> What is the best way to measure microseconds and on RIOT with the >> highest accuracy. >> >> [1] >> https://stackoverflow.com/questions/12703307/arm-none-eabi-gcc-printing-float-number-using-printf#25723994 >> [2] static uint32_t xtimer_now_usec() >> >> -- >> Best Regards >> >> Oliver Koepp >> _______________________________________________ >> users mailing list >> [email protected] >> https://lists.riot-os.org/mailman/listinfo/users > _______________________________________________ > users mailing list > [email protected] > https://lists.riot-os.org/mailman/listinfo/users
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