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by remaeder
Fri Aug 24, 2018 1:58 pm
Forum: HATs and other add-ons
Topic: PoE HAT - USB Ports not working - over-current (FIXED - New Hardware Release)
Replies: 327
Views: 83700

Re: (Solved - Faulty Unit) PoE HAT - USB Ports not working - over-current

Note the PoE HAT is rated for 2.5A at 5V which is 12.5W, so should be perfectly capable of supplying the Pi and USB.
You are right! Silly me.
by remaeder
Fri Aug 24, 2018 1:43 pm
Forum: HATs and other add-ons
Topic: PoE HAT - USB Ports not working - over-current (FIXED - New Hardware Release)
Replies: 327
Views: 83700

Re: (Solved - Faulty Unit) PoE HAT - USB Ports not working - over-current

What are you using to meausure voltages and currents ? Is it calibrated, professional equipment or just a cheapo voltage / current monitor ? it's one of those dongles with an USB male and female connector. I don't know how accurate it is. I don't know what the limits are on the USB current, but wou...
by remaeder
Fri Aug 24, 2018 11:43 am
Forum: HATs and other add-ons
Topic: PoE HAT - USB Ports not working - over-current (FIXED - New Hardware Release)
Replies: 327
Views: 83700

Re: (Solved - Faulty Unit) PoE HAT - USB Ports not working - over-current

Just how much power should I be able to draw from USB? With power via the PoE HAT the (idle) voltage on USB is 5.08V, and with my phone connected (for charging) it draws up to 0.46A, but breaks down with the over-current every 3-5 seconds. Powered via micro-USB, the voltage on USB is 4.78-4.97 (depe...
by remaeder
Sun Mar 19, 2017 3:45 pm
Forum: Interfacing (DSI, CSI, I2C, etc.)
Topic: Garmin GPS 18x LVC to Pi
Replies: 15
Views: 15315

Re: Garmin GPS 18x LVC to Pi

If I might post a quick reply.  The problem is that you actually have to read the INVERSE of the serial input.  Let me explain ever so briefly.      I tried to do something similar with an Ardurino.  The GPS unit puts out a signal that is to be read in a serial port...whether that is 5v or the 12v ...
by remaeder
Fri Jan 06, 2017 4:10 pm
Forum: HATs and other add-ons
Topic: The Pi as a GPS jammer
Replies: 3
Views: 2322

The Pi as a GPS jammer

This is really weird. I tried to measure temperature effects on ntp or chrony, using a Raspberry Pi 2 with an Adafruit GPS HAT, internal antenna. To increase the CPU temperature I did various stress tests. Everytime I did cat /dev/zero > /dev/null the GPS reception broke down. It was not electrical,...
by remaeder
Sun Dec 25, 2016 12:59 pm
Forum: Automation, sensing and robotics
Topic: Time&Temperature
Replies: 0
Views: 471

Time&Temperature

A GPS reference clock and temperature sensor After some trouble with the NMEA mode of the GPS module, discussed in this thread https://www.raspberrypi.org/forums/viewtopic.php?f=29&t=168961 , the result is now quite stable. The pps jitter is usually around 0.002ms, which is among the best seen in th...
by remaeder
Fri Dec 23, 2016 4:57 pm
Forum: Advanced users
Topic: Serial port high jitter (for GPS timing)
Replies: 6
Views: 2457

Re: Serial port high jitter (for GPS timing)

:D Success: the NMEA+PPS mode of ntp works quite well with the MTK MT3339 chip in the Adafruit GPS HAT. remote refid st t when poll reach delay offset jitter ============================================================================== oGPS_NMEA(0) .GPS. 0 l 47 64 377 0.000 0.104 0.003 +denebola.XX...
by remaeder
Fri Dec 23, 2016 3:27 pm
Forum: Advanced users
Topic: Serial port high jitter (for GPS timing)
Replies: 6
Views: 2457

Re: Serial port high jitter (for GPS timing)

I think I found the problem. The MT3339 chip is not suitable as an NMEA reference clock, because the sentences it outputs have no constant relationship to the start of the second. I enabled the timestamping in ntp refclock 20, (adding 128 to the mode). This logs the exact times at which the sentence...
by remaeder
Fri Dec 23, 2016 8:06 am
Forum: Advanced users
Topic: Serial port high jitter (for GPS timing)
Replies: 6
Views: 2457

Re: Serial port high jitter (for GPS timing)

The NMEA serial output data is totally independent from the PPS. The PPS is present on GPIO#4 according to https://learn.adafruit.com/adafruit-ultimate-gps-hat-for-raspberry-pi/pinouts Does the ntpd process need to be told to look at GPIO#4? The PPS is not the problem. that is working very well. :m...
by remaeder
Thu Dec 22, 2016 1:29 pm
Forum: Advanced users
Topic: Serial port high jitter (for GPS timing)
Replies: 6
Views: 2457

Serial port high jitter (for GPS timing)

I hooked up an Adafruit GPS HAT for implementing an NTP server. The PPS signal works very well, but the jitter of the NMEA data over the serial port (ttyAMA0) is very high, in the order of 50ms. This often causes ntpd to reject the local clock and sync to one of the network time sources. I understan...
by remaeder
Thu Oct 24, 2013 3:40 pm
Forum: Graphics, sound and multimedia
Topic: Get 192khz/24bit working?
Replies: 10
Views: 15401

Re: Get 192khz/24bit working?

192/24 definitely works these days. There is an excellent software squeeze player piCorePlayer, see https://sites.google.com/site/picoreplayer/home that outputs this resolution just fine over HDMI. I feed it into my surround receiver (Onkyo TX-NR5009) and it sounds great.

Roman
by remaeder
Thu Jun 13, 2013 7:19 am
Forum: Troubleshooting
Topic: max audio sample rate over HDMI?
Replies: 3
Views: 3703

Re: max audio sample rate over HDMI?

you made my day! :D
your test version of piCorePlayer streams 96kHz to my Onkyo receiver via HDMI.
It does stream 192kHz, too, but the output is garbled. I don't understand alsa enough to be able to tinker with the settings to see whether this problem could be solved.

Roman
by remaeder
Wed Jan 23, 2013 8:59 am
Forum: Troubleshooting
Topic: max audio sample rate over HDMI?
Replies: 3
Views: 3703

max audio sample rate over HDMI?

I am trying to get squeezelite ( http://code.google.com/p/squeezelite/ ) to work. Streaming FLAC at rates up to 48kHz works, but anything above that is resampled. Are there hardware/driver limits lower than what the receiver at the other end of the HDMI link is capable of? An EDID dump shows: HDMI:E...

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