Leon G1HSM gives talk on Raspberry Pi


Leon G1HSM gave an educational and insightful talk on the infamous Raspberry Pi to a well attended club room.

Leon gave a great talk at the Taplin Centre on Wednesday 24th of June, and made quite an impression with his insightful and education talk on the Raspberry Pi. Here is Leon’s report for his presentation.

Concept developed by Eben Upton of Broadcom, a large fabless chip supplier, in 2009. First boards were released in 2012. It’s a tiny credit-card sized computer originally based on the Broadcom BCM2835 SoC – a dual-core 700 MHz ARM processor with 256 Mb of RAM, piggy-backed together, and 26 I/O pins. It was later (2015) updated to a quad-core 1000 MHz processor with 512 Mb of RAM and 40 I/O pins. OS and program storage on flash memory card (Micro SD on the latest models). It was primarily intended to teach kids about computing for a small outlay (under £20) – requires a power supply, TV, keyboard and mouse. However, it has proved of more general interest. Over five million have been sold. Outside China, they are available from primary distributors Farnell and RS, as well as many secondary sellers.
Current models are the original Raspberry Pi 1 Model B+, the Pi 2 Model B, and the Pi 1 Model A+. The first two have four USB ports, Ethernet, HDMI, composite video, and camera and display connectors.

leon-raspberry-piThe Pi 1 Model A+ is a stripped down version with only one USB port. Both have 40 I/O pins. They can be used for video processing. The models I have are the Pi 2 Model B and the Pi 1 Model A+. One of the Pi 2s has a PiFace I/O card. I use them with a wireless keyboard and mouse and HDMI monitor. I use a 5 V battery power pack instead of a mains PS. Although it uses a USB cable for power, it draws too much power for connection to a PC USB port. Can also be controlled via the Internet using SSH (Secure Shell) in text mode – no keyboard, mouse or display needed. I can’t get SSH to work, though,  with my laptop.

Several OSs are available – Raspbian, based on Debian Linux is by far the most popular. Also: various other flavours of Linux and RISC OS (Archimedes), MS will be supplying Windows 10 for it. Easiest way to get going with a new RasPi is to download NOOBS from the web site, format an SD card (8 Gb +) in your PC and write NOOBS to it. When the RasPi boots from it, Raspbian is configured and you then have a bootable card. Need for shutdown before disconnecting power. It boots up into standard text-based Linux, and the xwindows GUI is run in the usual way with startx.

It’s quite easy to connect the Pi to the Internet, via a direct Ethernet connection or WiFi. Hardware is quite easy to interface via the 40-way connector, which has many of the ARM I/Os. Signals must be 3.3 V, anything more risks damage to the chip, and they are not protected from ESD. Best to buffer them with suitable interface chips as is done on the PiFace.

Lots of programming languages are available. Python is probably the most popular, and is very easy to learn. Python programs are easily entered and run from xwindows. C is also easy to use. There isn’t much of a market for software, because of the open source nature of the system. Only way to make money from it is probably by designing hardware.
There is lots of information and help available via the Internet – an official web site and 70 page monthly magazine called MagPi (PDF) – as well as meetings organised by enthusiasts and presence at Maker Faires etc. There is also a very active forum. No meetings around Hastings, AFAIK. Perhaps someone should organise something.

There is lots of amateur radio stuff for the RasPI – just typing “Raspberry Pi amateur radio” into Google brings up a vast number of hits. G0HWC has some interesting links, for instance.

Leon G1HSM


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