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by geoffr
Sun Sep 16, 2012 1:14 pm
Forum: Automation, sensing and robotics
Topic: Raspberry Pi Controlled Relays (for sprinklers) (Difficulty: Advanced)
Replies: 23
Views: 6426

Re: Raspberry Pi Controlled Relays (for sprinklers) (Difficu

I know it requires more hardware but I would add an AD converter to check the soil conductivity. Just add water when R is too high. Then you can do without all the timers etc. Of course then you could could also replace the whole RASPI with a pic. I'm busy with a similar concept at the moment, and ...
by geoffr
Fri Sep 14, 2012 1:45 pm
Forum: Interfacing (DSI, CSI, I2C, etc.)
Topic: Connecting a 5V relay board
Replies: 20
Views: 14689

Re: Connecting a 5V relay board

Here's the first prototype - only 4 LEDs hooked up, and using port B of the MCP23017, because that was convenient. The idea of using the MCP23017 is working. The level conversion from 3.3V to 5V using 2 mosfets is also working nicely.
by geoffr
Mon Sep 10, 2012 3:15 am
Forum: Interfacing (DSI, CSI, I2C, etc.)
Topic: Connecting a 5V relay board
Replies: 20
Views: 14689

Re: Connecting a 5V relay board

If doing analog unless you have extreme requirements greater than 10KHz continuous update in or out I2C will be fine. If doing audio unless it is short bursts of audio, from a a/d with an external buffer or to a DAC with an external buffer, use I2S, the vagueries of execution will cause problems wi...
by geoffr
Sun Sep 09, 2012 10:08 pm
Forum: Interfacing (DSI, CSI, I2C, etc.)
Topic: Connecting a 5V relay board
Replies: 20
Views: 14689

Re: Connecting a 5V relay board

Okay, I can fully relate to that, I was only under the impression that you took this route only out of desperation because you could not figure out the GPIO numbering. The main reasons for deciding to try the I2C approach were the fact that I realised that with GPIOs I was going to get limited quic...
by geoffr
Sun Sep 09, 2012 1:38 pm
Forum: Interfacing (DSI, CSI, I2C, etc.)
Topic: Connecting a 5V relay board
Replies: 20
Views: 14689

Re: Connecting a 5V relay board

Sounds like you like to take the more problematic route! Interfacing the GPIO's directly to an ULN2803 should work without any issue. GPIO allocation is not that complicated the SoC has 53 GPIO's only some of which are routed out from the chip to the board, and of these only some are routed to the ...
by geoffr
Sun Sep 09, 2012 12:57 pm
Forum: Interfacing (DSI, CSI, I2C, etc.)
Topic: Connecting a 5V relay board
Replies: 20
Views: 14689

Re: Connecting a 5V relay board

I've given up on the idea of using the GPIOs directly, and will give the I2C bus a bash. My current thinking is still to use a ULN2803 to drive relays. - In the attached diagram I have only got as far as the indicator LEDs for each output. I plan to use the other 8 lines from the MCP23017 as inputs....
by geoffr
Sat Sep 08, 2012 9:33 pm
Forum: Media centres
Topic: Airtunes streaming from iTunes to XBMC
Replies: 2
Views: 2867

Re: Airtunes streaming from iTunes to XBMC

It looks like the default build on the RPI excludes Airtunes, for no better reason than the fact that libshairport is not installed by default. I wonder why the developers of RaspBMC and OpenElec don't include that functionality.
by geoffr
Sat Sep 08, 2012 3:38 am
Forum: Media centres
Topic: Airtunes streaming from iTunes to XBMC
Replies: 2
Views: 2867

Airtunes streaming from iTunes to XBMC

I was wondering if anyone has successfully got audio only streaming from iTunes to XBMC working? I have tried running Raspbmc, but it would only support Airplay (video), and was not recognised by iTunes for audio playback. Some of the material I have read suggests that this might have been addressed...
by geoffr
Thu Aug 23, 2012 12:38 am
Forum: Interfacing (DSI, CSI, I2C, etc.)
Topic: Connecting a 5V relay board
Replies: 20
Views: 14689

Re: Connecting a 5V relay board

Thanks Kaos.

Based on what you are saying, I am probably just using either discrete transistors or an array like the ULN2803 to directly drive relays.
by geoffr
Wed Aug 22, 2012 11:39 am
Forum: Interfacing (DSI, CSI, I2C, etc.)
Topic: Connecting a 5V relay board
Replies: 20
Views: 14689

Connecting a 5V relay board

I am looking at the idea of connecting a 5V relay board (such as this one: http://www.elecfreaks.com/store/8-channel-5v12v24v-relay-module-p-268.html to the GPIO port on the PI. While the schematic of this board indicates that it is using transistors to switch the relays, I am cautious about whether...

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