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by Rob Meades
Mon Apr 16, 2018 4:26 pm
Forum: Advanced users
Topic: Clock drift
Replies: 7
Views: 1119

Re: Clock drift

Oh, that's interesting, I'd assumed the BC chip had RTC HW of some sort inside but I guess that, without a clock crystal or similar on the board, even if it did, it wouldn't be much more than an R/C network accurate. None of this is critical for me, I was just thinking out loud really. Thanks for al...
by Rob Meades
Mon Apr 16, 2018 3:40 pm
Forum: Advanced users
Topic: Clock drift
Replies: 7
Views: 1119

Re: Clock drift

True, but I don't know what the frequency of such checks are. If daily then you could still be ~10 seconds out.
by Rob Meades
Mon Apr 16, 2018 3:19 pm
Forum: Advanced users
Topic: Clock drift
Replies: 7
Views: 1119

Re: Clock drift

Hmm, yes, it seems from browsing the web that of the order of 10 seconds a day for a PC is not unusual and my 150 PPM number (~12 seconds per day) would be the combination of the Pi and internet server drifts. Worth remembering how inaccurate computer time is.
by Rob Meades
Mon Apr 16, 2018 2:36 pm
Forum: Advanced users
Topic: Clock drift
Replies: 7
Views: 1119

Clock drift

I have an application that streams audio from a Raspberry Pi to a server on the internet. As part of this application I measure the round-trip delay by periodically sending a packet with a microsecond-timestamp in it, which the server echoes back to me. This is all works fine. Just for interest, I a...
by Rob Meades
Mon Feb 26, 2018 12:13 am
Forum: HATs and other add-ons
Topic: Supplying external power to a USB peripheral
Replies: 0
Views: 367

Supplying external power to a USB peripheral

I'm using a Hologram Nova USB modem with my Raspberry Pi (B+ or Zero W). In poor coverage conditions a 2G/3G cellular modem will draw very short peaks of close to 3 Amps, which can brown-out the Pi. Hence I would like to provide external power to this USB connected device. Before I get my soldering ...
by Rob Meades
Thu Feb 01, 2018 8:34 pm
Forum: Raspbian
Topic: ALSA microphone volume configuration
Replies: 2
Views: 10616

Re: ALSA microphone volume configuration

That's excellent, many thanks. FYI the critical change was removing the mmap part. i.e. the minimal change I needed was: pcm.mic_hw { type hw card memsmic channels 2 format S32_LE } pcm.mic_sv { type softvol slave.pcm mic_hw control { name "Boost Capture Volume" card memsmic } min_dB -3.0 max_dB 50....
by Rob Meades
Wed Jan 31, 2018 3:59 pm
Forum: Interfacing (DSI, CSI, I2C, etc.)
Topic: STICKY: The I2S sound thread.
Replies: 925
Views: 455629

Re: STICKY: The I2S sound thread.

Hi I2S/ALSA experts. I've got a very long way with connecting an I2S microphone (ICS43432) to my Pi but have failed at the very end in that I cannot get the capture volume boosted. The microphone is working correctly, it's just far too quiet and my attempt to boost the volume, using alsamixer and al...
by Rob Meades
Wed Jan 31, 2018 1:42 pm
Forum: Raspbian
Topic: ALSA microphone volume configuration
Replies: 2
Views: 10616

ALSA microphone volume configuration

Following the instructions here I have successfully connected an I2S microphone (ICS43432) to my Raspberry Pi B+ running the lite version of Stretch 4.9.59-v7 (controlled via SSH). However, whatever I do (following the posts here , here and here ) I cannot get volume boost to work. Can anyone tell m...
by Rob Meades
Sat Nov 23, 2013 3:32 pm
Forum: Other projects
Topic: Found Internal USB hub for embedded projects
Replies: 14
Views: 11894

Re: Found Internal USB hub for embedded projects

Aaah, sorry, yes, I was confused by the terms "upstream" and "downstream". I had thought the input was USB 1.1 or USB 2, but it's USB 1.1 *and* USB 2, you just need to know what's connected to what. All sorted now, thanks.
by Rob Meades
Thu Nov 21, 2013 11:08 pm
Forum: Other projects
Topic: Found Internal USB hub for embedded projects
Replies: 14
Views: 11894

Re: Found Internal USB hub for embedded projects

I know this is a rather old thread but I'm hoping some of you guys are still and around and have this thread marked as 'notify'. I purchased one of these NZXT USB expansion cards for the Pi but I have the problem that only port 5 on the NZXT works for me - no devices enumerate on any of the other po...
by Rob Meades
Sat Nov 09, 2013 12:08 am
Forum: Troubleshooting
Topic: Reducing SD card partition size on a live Pi
Replies: 10
Views: 17797

Re: Reducing SD card partition size on a live Pi

All working now, so, for the record, here is what I did. It is based on the article here: http://www.instructables.com/id/Raspberry-Pi-Resize-Partitons-Use-all-free-space/?ALLSTEPS …but I can’t find a way of replying with a formatted post on that site hence I’m posting it here. You may have got here...
by Rob Meades
Fri Nov 08, 2013 12:11 am
Forum: Troubleshooting
Topic: Reducing SD card partition size on a live Pi
Replies: 10
Views: 17797

Re: Reducing SD card partition size on a live Pi

OK, I was being stupid - I was only dd ing partition 2 not the whole of the SD card, no wonder it wouldn't boot in the Pi, trying again...
by Rob Meades
Thu Nov 07, 2013 10:00 pm
Forum: Troubleshooting
Topic: Reducing SD card partition size on a live Pi
Replies: 10
Views: 17797

Re: Reducing SD card partition size on a live Pi

Sorry about the silence guys, have been trying to help myself but not yet made it. I, too, realised that I could get an Ubuntu distribution (12.10) on a bootable USB stick and so I did a resize2fs there: resize2fs -f /dev/sde1 15377120s ...where 15377120 sectors is the right size to fit both partiti...
by Rob Meades
Wed Nov 06, 2013 5:21 pm
Forum: Troubleshooting
Topic: Reducing SD card partition size on a live Pi
Replies: 10
Views: 17797

Re: Reducing SD card partition size on a live Pi

OK, I have tried resize2fs but it will not resize a file system that is mounted (which is the only option I have since I only have Linux on Pi's with the one SD card in them). Is there a way to resize a mounted file system or am I b*ggered?
by Rob Meades
Wed Nov 06, 2013 8:16 am
Forum: Troubleshooting
Topic: Reducing SD card partition size on a live Pi
Replies: 10
Views: 17797

Re: Reducing SD card partition size on a live Pi

Silly me, I suppose that would be 'resize' wouldn't it? I'll go RTFM...
by Rob Meades
Wed Nov 06, 2013 8:14 am
Forum: Troubleshooting
Topic: Reducing SD card partition size on a live Pi
Replies: 10
Views: 17797

Re: Reducing SD card partition size on a live Pi

Aaah, OK, I've not come across any instructions on shrinking the file system first. Any pointers on a command to do that?
by Rob Meades
Tue Nov 05, 2013 10:07 pm
Forum: Troubleshooting
Topic: Reducing SD card partition size on a live Pi
Replies: 10
Views: 17797

Reducing SD card partition size on a live Pi

I have an 8 gig SD card with file system fully expanded. I want to use Win32DiskImager to make a copy of the SD card for use in a second Pi and have hit the issue that not all SD cards are the same size, hence I can't write a saved image from Win32DiskImager to my second card as it's very slightly s...

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