Raspberry Pi Forums

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I'm also interested in this... I'm home brewing beer and I'm using a Pi to control the temperature based on data from a set of 1-wire thermal probes. It could be quite interesting to parallel SG to thermal output.

aquarat

Thanks MattF, that's good advice. My devices can lose changes

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I've been having this issue too... usually it's not an issue because I shut down my Pis or I put them on a battery backup, but recently I connected two of them to two LCD displays and the displays are often powered down by accident. I was thinking that making the rootfs read-only and then having a s...

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My Raspberry Pi running this NTP configuration has been up 250 days

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I just installed mysql... and so far it's working quite well for my project (Power meter reading).

aquarat

Just for those who are asking about a guide / technote / tutorial : I made a post/tutorial on how to duplicate my setup on page 5 of this thread.

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Code: Select all

 11:01:29 up 53 days, 19:39,  2 users,  load average: 1.56, 1.60, 1.82

It's the most accurate time server I've ever had... and it's proving to be very reliable

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Hi Chuck

I didn't realise that, thanks for the explanation @ portA/B. The Pi's UART can only run TTL on 3.3v. It is not over-voltage tolerant, that's why I'm using a MAX232-based converter (which so far has worked very well).

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Hey Exciton Ah! I honestly had no idea the TT4 had a MAX232(?) in it lol :P I would assume that you have to bypass the chip to use the TT4 with a Pi because the Pi's pins aren't over-voltage tolerant ? sending a RS232 voltage down onto a TTL-Pi pin could damage it ? I worked out what was causing the...

aquarat

Thanks for all the advice. I haven't had a chance to work on this, hopefully I'll have time today. I found this document : Ceiling Fan Speed Control - Single-Phase Motor Speed Control Using MC9RS08KA http://i.stack.imgur.com/4s1xQ.jpg The document uses a microcontroller with a lower sampling frequen...

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Haha, no worries, I'm glad I covered that point

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mmm... well there are three things, from my experience with the Pi that could potentially cause serial comm issues : (1) The most obvious : are you use a decent TTL -> RS232 level shifter ? http://devrat.aquarat.za.net/assets/aprsPi.jpg http://devrat.aquarat.za.net/assets/ekm/IMG_20120731_092441.jpg...

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Hi My APRS Pi has been working flawlessly. Here are the major config files on my system : /etc/inittab : # /etc/inittab: init(8) configuration. # $Id: inittab,v 1.91 2002/01/25 13:35:21 miquels Exp $ # The default runlevel. id:2:initdefault: # Boot-time system configuration/initialization script. # ...

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Hi Gordon I found your wiringPi library when I first started looking for PWM-related stuff. I was/am specifically after hardware PWM (which is available on GPIO18?) because I hoped that 1) it'd provide higher sampling rates 2) it'd be less prone to multi-tasking related timing error and 3) it'd use ...

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The result of a square wave output to the audio interface : http://devrat.aquarat.za.net/assets/osc03.jpg http://devrat.aquarat.za.net/assets/osc04.jpg The core chunk of code that generated this (Java) : for (int i = 0; i < buf.length; i++) { if(i % 2 == 0) { buf[i] = (byte) 255; } else { buf[i] = (...

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I just found a programme I wrote 4 years ago that used the audio output as an Software Defined Radio (emulated DCF77 time signals)... gonna quickly hack it to do PWM.

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Here's a thought... PWM... on the audio output... ? 44.1kHz sample rate...

aquarat

Hi Janek Thanks for the thought, but it would be damaging and highly inefficient to turn a pool pump (single phase, 240VAC induction motor) on and off for seconds at a time. However, you mentioned a magical word : "triac" And this has got me thinking; Triacs can turn loads on and off very ...

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Hi I'm currently using a Raspberry Pi to control my pool pump (NTP means it'll always turn on at the right time... and it's easily programmable). I was wondering, would it be possible to use the Pi to control the speed of the pump ? The pump is a 750w, single phase device. It has a capacitor on it. ...

aquarat

Thanks Paul, there's no rush :) . @ peterwillcn : I have a Motorola Oncore UT+, but as yet I haven't been able to get this working with ntpd. I haven't tried very hard. The GPS I'm using uses NMEA over ttyAMA0 whereas the Motorola GPSs use the Motorola Binary protocol... NTPd does support this but I...

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Thanks bytecounter

I'm busy downloading the various tools/source to compile the kernel myself... but my objective is mdadm support

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Hey Paul I'm currently using the custom kernel on the Raspbian distribution. I just connected an external GPS antenna to my Adafruit GPS receiver, so that might further improve the jitter (although I don't think ntpd can go below 0.002?) . If it makes a difference I run ntpd as root. The first time ...

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Some hiccups, I don't know how to "elegantly" persistently link (ln) /dev/ttyAMA0 [target] to /dev/gps0 and ln /dev/pps0 to /dev/gpspps0.

At the moment I'm doing it with a cron job.

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Pic : (hosted on a pi) http://41.134.20.29/gpsandpismall.jpg hey the gps module type ? plesae hardware wiring diagram, write a wizard, I also want to build a list in accordance with the practice as well as hardware. I don't really understand what you're saying peterwillcn ? But I'll probably make a...

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And a further update :

You can clearly see a very large improvement between the x86/GPS-OXCO combination and the Pi/GPS-PPS solution.

The x86 system read the PPS using the DCD line on the RS232 port.

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Re: Hydrometer Pi

Re: SD corruption on power outages

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Re: NTP PPS

Re: How I compiled MariaDB and Phidget drivers

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Re: Pool Pump and PWM/GPIO speed control

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Re: Pool Pump and PWM/GPIO speed control

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Pool Pump and PWM/GPIO speed control

Re: NTP PPS

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