On Friday 02 June 2017 17:29:24 Bertho Stultiens wrote: > On 06/02/2017 01:46 AM, Bertho Stultiens wrote: > > Problem 1: > > The RPI3 has dynamic frequency scaling activated by default > > (ondemand governor). This makes the Pi hop between 600MHz and 1.2GHz > > core frequency. Very annoying and makes realtime rather > > unpredictable. > > There are actually two lines that must be added to rc.local: > echo -n 1200000 > > /sys/devices/system/cpu/cpufreq/policy0/scaling_min_freq
Added also. > echo -n performance > > /sys/devices/system/cpu/cpufreq/policy0/scaling_governor > > The first one forces to hop to 1.2GHz. The current cpu frequency, > apparently, may otherwise hang onto the 600MHz value (in > .../cpu0/cpufreq/cpuinfo_cur_freq). > > > Problem 2: > > The SPI peripheral input frequency appears to be hopping between > > 400MHz and about 250MHz. This probably originates somewhere in the > > Linux kernel as the kernel is in charge of clock-generation. > > There may be an interaction with the power supply and the > frequency-lock of one of the BCM283[567] PLLs. > > Several power-glitches caused the system to crash after I installed a > full graphical desktop version. It turned out I was using a cheapo usb > supply with bad regulation. > > The problems seem to stop now that I have attached a bench-PSU set to > 5V directly on the 40-pin header's 5V input. I needed to increase the > voltage to 5.1V after the red LED still was blinking once in a while > (probably indicating too much noise on the power line with my long > wires without decoupling capacitor on the end). > > It may be worth checking the actual 5V line for noise too. 5mv? 4 amp box, haven't had a problem. Thanks Bertho. One thing I've noted is that in one switch starts both the monitor and the pi, the monitor isn't ready I assume to respond to an EDID query by the time the pi issues it. So I've had to pull the pi's power plug for about 2 or 3 seconds mid-boot. Then plug in the teeny usb plug again, and I get video on that reboot. Is there quick and likely dirty way to make the pi wait 2 or 3 seconds before loading things up? Thank you Bertho. Cheers, Gene Heskett -- "There are four boxes to be used in defense of liberty: soap, ballot, jury, and ammo. Please use in that order." -Ed Howdershelt (Author) Genes Web page <http://geneslinuxbox.net:6309/gene> ------------------------------------------------------------------------------ Check out the vibrant tech community on one of the world's most engaging tech sites, Slashdot.org! http://sdm.link/slashdot _______________________________________________ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
