Ramblin' Dan's Workshop

The Sanctum of Fine Art and Invention

Raspberry Pi

Articles on the development of Raspberry Pi (1 & 2) for use in home and Amateur Radio applications.

Raspberry Pi1 & Pi2

DSC05836I just received my new Raspberry Pi2 B micro computer. It is shown on the right side of this photograph. The Pi1 version is on the left all connected and operating. There is a slight delay in firing up the new Pi2 as I ordered the wrong size memory chip. The Pi2 uses a micro SD where as the Pi1 uses the standard size SD memory.

As it turns out it is a fortunate mistake as I actually need a larger memory card for the Pi1. I was using a small 2GB and shown here it is running with the new 8GB I had ordered. The new card is also class 10 and is much faster than the old 2GB. I have no idea the speed but since they are not listing standard 2GB SD cards, it must have been very slow R/W.

A new 8 or 16 GB micro class 10 SDHC  costs between $13 - $15 so is not a huge investment. The 16 GB (~40MB/s) is actually faster than the 8GB (30MB/s) but then it could all just be marketing. The device they are used in is the other half of the speed formula.

I have studied the technology behind SD cards and there are invisible very hi tec algorithms running in these memory chips protecting data from bit failure. Storage bits are constantly being moved around to equalize read/write cycles to every available bit. No one area is overused. Amazing technology for the price and reliability. My corporation ran heavy duty cycle tests for months on memory cards to determine the failure rates if used in our equipment. The fix-on-the-fly memory algorithms gave us much better than expected MTBF results. 

More to come on what I do with these tiny computers.

Raspberry Pi 2 First Slice

DSC05838I purchased a SanDisk Ultra PLUS 16 GB Micro SDHC UHS-1 card for ~$16.00. It claims speed up to 48 MB/s. That is about as cheap and good as they come. Usually cheap and good aren't found in the same item. All you can see in the picture is the tiny black tab of the memory card sticking out at the bottom edge.

The raspberry Pi 2 Model B 1GB is marketed as being 6X faster than the original Pi 1. For more information check out https://www.raspberrypi.org/

I agree. It is MUCH faster than my older Pi 1 version. In fact it is so fast I believe it could serve as a main computer for my Ham Radio station. It's no rock crusher but it runs as good as my Asus netbook. I am not saying that is my purpose for this machine. At first look here it appears it is a good Linux machine for writing code. It has an excellent screen display using (HDMI) output and it uses any standard keyboard of choice.

At this writing I would pick the netbook over the Raspberry for overall ease of use as a conventional portable computer as the netbook has the screen and keyboard all in one package. The benefit of the Raspberry is it is equal in speed to the netbook and is so open for experimentation and modification - and at least  10X cheaper in cost.

Pi 2 is a great little machine for a very low price. It fits in well with the Basic Stamp and Propeller single board computers I have worked with for special purpose dedicated computing, but with a much more powerful on board I/O capability. Hobbyist hardware hackers never had it so good and that includes me.

SPi GertBoard

This is a commercial I/O test board for the Version 1 of the Strawberry Pi (SPi1). It is called the GertBoard and is available from element14.com. I am NOT recommending this board as the software is a bit dated and I have found some software errors. The board is designed for use with the old pin-out of first generation Strawberry Pi. Hackers could adapt to the new version 2 of SPi (SPi2).

Since I do have a version 1B of the SPi, it is useful for me and better than anything I could build for myself. It's actually what I would call an experimenters board and by selecting jumper wires and header shorting caps, many configurations can be assembled for testing code and experimenting. For me it is worth the investment. It may not be good for others, so no recommendation from me. Your decision.

Here I am showing one of the very first things I programed on my Imsai 8080 probably in 1976 nearly 40 years ago. I wrote some machine language code to cycle a row of front panel LEDs that were setup as an output port.

This time I used higher level language using both "C" and "Python". This is a Python run. The C code had a problem either with the board or how it ran in the RPi 1. The fifth LED would not illuminate. You (if you are sharp) can see here with Python, the #5 LED is working.

However, with Python there is now an extra LED that is turning on, on the left end of the row in the last few sequence runs, that isn't written in the program to come on.

I figure it is some sort of "carry over" bit in the GertBoard that is firing the left end LED. There is not even a jumper wire on the board to tie the output pin from the SPi1 to that LED input. That hardware flaw would drive a novice programmer bonkers, so that's why I can't recommend the GertBoard.

The demo software is provided on line by the board maker  but with only with an "as is" statement. I can understand that. I have hacked the code and added to it but the fault remains. All in all it does serve a purpose for me and I can live with these issues. I need a board with which to experiment.

I will be looking for other hardware add-ons as there are now hundreds of accessories that can be used. I am looking for what I can use with the new series two RaspBerry Pi. It has a larger I/O bus and is very much faster. The RPi 1 will still have a place with low power embedded applications where power use is more important than speed. Also the price of the RPi 1 has gone down ten dollars.

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