[ 01.11.2015 ] I’ve been experimenting with the latest generation of RaspberryPi Linux computers from the University of Cambridge. A RaspberryPi is a very small, very inexpensive 700MHz 32bit ARM ( ARM11 ) powered Linux computer with HDMI video that boots from a micro SD card and powers off of USB. I am intrigued by the fact that the 2×20 0.100″ header can directly power my Nano FPGAs and provides UART serial and also SPI serial ( up to 125 MHz ). 1st install was with NOOBs – which I am now abandoning for Raspian standalone. The NOOBs bootloader always spits out boot trace information to the serial port which is a problem if I plug an FPGA into it. My current experiment is to boot Raspian from the uSD card and have it mount a Sandisk USB 3.0 flash drive ( from Amazon 16 GB for $11 ) that contains the full OS. I want to time how fast it is to boot from uSD by itself versus uSD and then USB. USB should be faster all around. Historically from my original Pi, I know that uSD cards get easily corrupted with power removal without proper shutdown. I hope to minimize this frequent problem via using low profile USB flash drives for the majority of the Linux Filesystem.
[ 12.30.2014 ] Fabbed out the Pi to FTDI Nano board.
This board provides Nano compatible x8 and x4 headers connected to GPIO pins of the Pi. The x4 has the SPI interface. It also has a FTDI compatible 1×6 for either connecting to a Nano FPGA or to a FTDI cable to a Host-PC. The FTDI connection to PC is great because from a PUTTY terminal, you can login to the Pi and interact with it completely headless.
[ 01.02.2015 ] Fabbed out the NanoPi board.
While experimenting with Pi software configuration, I realized ( via Googling ) that it is possible to configure the Pi to login automatically and run a python script on power on completely headless. This would make for a fantastic embedded test fixture ( chips or boards ) as all the software can be written in the Python scripting language. Historically an embedded test fixture would require embedded C. I have experience in this and know that its x10 slower to develop embedded C versus scripted Python. The RaspberryPi has ethernet and mounts my NAS drive and has an SSH server, so actual development can be done on my real Linux workstation ( 3 GHz Core i7 running Fedora ) and once working, can be copied on to the micro SD for complete standalone operation.