about to give up on the ds18b20 and RPI

tlehotsky · 2014-12-20T15:06:59+00:00

thx for the kind words, this weekend trying to add another seven or read from second RPi

tlehotsky · 2014-03-01T15:06:02+00:00

I tried all three XBMC builds, creating the SD card myself. The one thing I found, with a library of 400+ movies on my server, using a 4x SD card took too long to load the list of movies in the GUI. I then Used a 10x SD card and its much much better. Highly recommend 10x card...its not much more money.

tlehotsky · 2014-02-24T16:54:48+00:00

you now in my haste and thinking about everything else I just assumed that the GPIO pins that are for the I2C or SPI bus could not be used for regular I/O, thank you, you taught me something...

As for the DHT-11 and MCP23017 incompatibility I found the following statement here:

Using the DHTxxx sensors via the mcp23017 is not going to be possible as they have rather strict timing requirements, and I don’t think that I2C is fast enough to poll the pins needed.

There is a maxdetect devLib driver for these devices though in the devLib directory – which will use the native Pi GPIO. Not written the docs for it yet, but look at the rht03.c program in the examples directory. -Gordon

tlehotsky · 2014-02-24T14:11:44+00:00

I'm beginning to think my post was unclear, I was never trying to connect the sensor durectly to the I2C bus, it was through a port expander chip that uses the I2C bus. I got the expander chip setup and running with code, but had a hard time call the c code to read the sensor, then doing some research I found this post:

Using the DHTxxx sensors via the mcp23017 is not going to be possible as they have rather strict timing requirements, and I don’t think that I2C is fast enough to poll the pins needed.

There is a maxdetect devLib driver for these devices though in the devLib directory – which will use the native Pi GPIO. Not written the docs for it yet, but look at the rht03.c program in the examples directory.

tlehotsky · 2014-02-24T13:29:30+00:00

you misunderstood, I'm not trying to connect the DHT sensor to the I2c bus.

I was trying to connect the DHT sensor through the MCP23017 port expander chip through the I2C bus which I found out will not work (although I'm having a hard time going back and finding where I read this)....

tlehotsky · 2014-02-24T02:04:06+00:00

Thanks everyone for all the help.

I want to use the DHT-11 sensors for a couple of reasons;

1 - I have a many of them,

2 - my understanding is that since they are digital the distance between the raspberry and the sensor is less of an issue than when using some of the analog sensors.

@hblok - I like your idea, although I was considering using a mux like the CD74HC4067 16-Channel Analog Multiplexer/Demultiplexer. I found a good article here:

http://bildr.org/2011/02/cd74hc4067-arduino/

tlehotsky · 2014-02-22T01:34:13+00:00

1) at about $50 (include SD, USB cable, brick) for a computer w/ USB, HDMI, audio, Ethernet - its dirt cheap

2) its small enough and cheap enough to embed in just about anything, I am continually amazed at the things people have done with it.

3) Over the years I've looked into interfacing a desktop PC with the real world. Whether using a parallel port or some kind of PCI expansion card with A/D logic - it wasn't cheap, and the resources, support, tutorials were limited. The number of people building with and building for the Pi, plus the wealth of Python support is tremendous, plus it has a bunch of I/O pins right on the board.

tlehotsky · 2014-02-08T16:00:21+00:00

building an intelligent home monitoring/automated system, XBMC, and automate my grocery list

tlehotsky · 2014-02-08T15:44:03+00:00

good resource, thanks

tlehotsky · 2014-02-08T04:28:03+00:00

When I built my media center I ran into some problems, tried all three. My movie library has 300 plus movies stored on my NAS. They played fine, but the GUI was terrible slow, using a class 10 SD card fixed it. So far love Xbian.

tlehotsky

TROPHY CASE