The "Raspberry Pi" as a Transmitter

This coming Saturday I shall be demonstrating the Pi transmitting. 

Over the last couple of years, more and more 'fiddlers' and Radio Amateurs have been using the Pi for various transmissions. Some legal some not.

What power does it send out?

What frequencies can it transmit?

Is it clean? Does it need a filter?

To hear the answers to these and other questions, be at the club at 13:00.

73

John ZS6WL

The Club has decided to hold a 'flea market'

This 'flea market' coincides with the 'Ham Comp - Raspberry Pi' session...

So the last session was the last one for the year. Sorry guys. But it will give you a chance to visit the club and purchase things as well as socialise. [OK that was annoying, Google/Blogger decided that my language is Canadian English.]

I shall be there to support and chat.

Hopefully it won't be as hot as this last week or this one is going to be.

73

John ZS6WL

This time I have no intention of missing the meeting...

So this coming Saturday, is the Ham-Comp / Raspberry Pi Meeting.

I have some developments for you to look at. 
Romeo has sent his apologies already. He and his wife will be in Paris [the Free State one]

Any items that you would like to discuss? Please let me know beforehand.

73
John ZS6WL

Club House at 13:00 +/- RAE revision

I know why the Leopard went up the tree. But how did they get the girl up there?

Due to unforseen circumstances the Clairvoyant's society will be closed tomorrow. Sorry!

I cannot make it to Ham-Comp/Raspberry Pi tomorrow afternoon...

The week has been a chaotic one with fireplace removal and preparation for new floors. With yesterday being an absolute disaster, they had to screed the rooms floors. The floors are drying as I type this... they have just phoned to say that they can install tomorrow afternoon. Which is good news for me.

Of course I shall probably see you all at the flea market next week. But this carpet replacement has been coming for years!

Sorry for the delay...see you next time.
73
John ZS6WL
 

Ham-Comp / Raspberry Pi Session 7

Tomorrow is the postponed meeting at the Club House for Raspberry Pi and Ham-Comp. I say both because the Pi' is starting to get used for 'other' things...

I am going to be there from 13:00 to 17:00 with a short presentation on Peripherals and SPI/I2C. 

This all assumes I can defrost in time...

73

John ZS6WL

 

So tomorrow is SCOPEX not Raspberry Pi

So you have to wait another week for the Raspberry Pi session. Any thoughts on what we might cover?

• Maybe the use of an LCD panel with the Pi?
• Maybe a temperature monitor 'app' ?
• With a web server page that can be accessed from the Internet? [Oh sorry that's been done...maybe that is a project in itself?]

Hardware - I found an HDMI to DVI connector adapter at the China Mall. I also found that I could install REAL ENGLISH Dictionary into Firefox. So the spell checker in this blog does not consider me a Canadian!

Nico phoned me this week with an application for the Pi that measures pressure in a pipe. Unfortunately the sensor is an analogue sensor. So I went looking for an A2D chip that can do the job... maybe that is another subject for Saturday week?

73

John ZS6WL

Raspberry Pi - Getting the temperature sensor to work.

I had 'issues' with getting the temperature sensor to work with the Raspberry Pi. So I did some more searching...

Add the following line to /boot/config.txt
dtoverlay=w1-gpio

Then you can 'probe' the Pi...

sudo modprobe w1-gpio
sudo modprobe w1-therm

To check this has 'worked':-

 
cd /sys/bus/w1/devices/
ls
 

This should show the temperature file:-
10-00080254a833 [ or similar file name][IF it doesn't, you need to check everything.]

Change directory to it:-

cd 10-00080254a833
 

To 'read' the DS18x20 [mine is so old...]
cat w1_slave

This should show something like this :-

pi@raspberrypi /sys/bus/w1/devices $ cd 10-00080254a833
pi@raspberrypi /sys/bus/w1/devices/10-00080254a833 $ cat w1_slave
23 00 5d 58 ff ff 04 10 3d : crc=3d YES
23 00 5d 58 ff ff 04 10 3d t=17500
pi@raspberrypi /sys/bus/w1/devices/10-00080254a833 $

Yes! It really was 17.5C in the study. Cool now to find a C program to get the reading...

Brad's Raspberry Pi Blog - has the answer. 

But only one 'gotcha'! The temperature sensor in current day use is a DS18B20 and mine is a DS1820. The 'output' is not '28-' but a '10-'. This requires a small change to the C program. A recompile later and all is well. Reading the sensor to three decimal places. Hmm.