Back again after a long wait…

I recognise that it’s been a while since I last wrote anything here, but I’ve been keeping myself busy and haven’t been inclined towards writing. However, I have been working on a few things which seem rather relevant to the scope of this blog. I’ve found quite some use out of the NAS that I mentioned in my last post, I’ve been working on electronics experiments and have further built up my Raspberry Pi collection with a new addition.

Synology DS416 – Performance Benchmarking

In order to get some sort of understanding of the performance of my Synology NAS, which I have connected through its two 1GbE ports to an 8-port Netgear GS108E switch, I decided to use IOmeter to pit it against the data storage drive I have in my computer, a 3TB 7.2K Seagate SATA disk. As artificial as the results from IOmeter can be, it still gives a good idea of what the speeds are like against the SATA disk on which I put most of my non-OS files. Using a maximum disk size of 1,048,576 sectors (or 512MB) and leaving the tests running for 20 minutes each, I got the following results, where Z: corresponds to an iSCSI volume on the NAS and D: corresponds to the SATA disk:

4KiB; 50% read, 50% write; 50% random

Z: 692 IOPS, 2.84MBPS, 23ms latency

D: 185 IOPS, 0.76MBPS, 86ms latency

64KiB; 0% read, 100% write; 0% random

Z: 552 IOPS, 36.15MBPS, 29ms latency

D: 849 IOPS, 55.62MBPS, 18ms latency

64KiB; 100% read, 0% write; 0% random

Z: 1787 IOPS, 112.33MBPS, 8.9ms latency

D: 939 IOPS, 62.91 MBPS, 16.6ms latency

In the 4KiB test, which would appear to be the most representative of real-world tasks involving using the storage as a standard drive (although I would expect more reads and more random data to be passed through in that circumstance), the NAS clearly had the advantage, with three times the IOPS, three times the data throughput and a third of the latency. The NAS is not as good in the 64KiB write-only test, possibly as a consequence of the RAID penalty applied since the four disks in the array are set up in RAID 5, but the NAS takes the lead again in the 64KiB read-only test, both of which might represent me writing or reading in a manner befitting the drives’ purposes as archival drives. The read-only performance of the NAS also lines up with the maximum network read throughput that I’ve seen.

I’ve also installed a Windows 7 VM on a separate 1TB iSCSI volume on the NAS which I’ve used with VMware Workstation to provide me with some ability to play Windows games without having to reboot my system. There have been some issues with stuttering, which would be a deal-breaker in action games but has been sufficient for the strategy and WRPG titles that I have been using it for, like Hearts of Iron III and Planescape: Torment.

Electronics experiments – a new collection of gear to try out!

The electronics experiments that I had been doing before with my Raspberry Pi had gone on the backburner for a long time. However, with Robot Wars back on the BBC recently and my younger brother interested in building a robot, I’ve decided to get back into the world of electronics experiments with the idea of getting enough knowledge to build a basic robot, at which point I can get my brother involved with various tasks. To that end, I’ve stocked up on a whole new list of components. At the moment, most of these are limited to things I can stick on a breadboard instead of motors and so on, but the components I’ve picked up include MCP23017 I/O expanders to complement the MCP23008 that I already have, an alphanumeric LCD display, a few AY-3-8910 sound chips, along with piezoelectric speakers, LM386 amplifiers and audio jacks and a few crystal oscillators for the sound chips. I’m also expecting a delivery of SN76489 sound chips within the month.

So far, I haven’t got too far; I’ve done some experiments to illustrate that the MCP23017 chips and LM386 amplifiers work, but I’ll need to learn how to solder before I can test the alphanumeric LCD and the AY-3-8910 sound chip will require some time to understand before I can get it tested.

Anyway, here’s a basic schematic using the LM386 amplifier:

LM386 Amplifier_bb

Pin 5 on the LM386 IC is connected to a voltage source between 4V and 12V, while pin 4 is connected to ground. Pins 2 and 3 of the LM386 are hooked up to the ground and the positive line of the input from the audio jack respectively. Pins 1 and 8 can be hooked up to a capacitor with a maximum value of 10kΩ to increase the gain, but I decided to go without and use the internal gain of 20 just to test that the IC worked. Then, pin 6 is connected to the positive terminal of a piezoelectric speaker, which produces sound, although the datasheet recommends using various capacitors in order to smooth out the sound and reduce noise. Pin 7 of the LM386 provides a bypass for sound without amplification, but this goes unused in this circuit.

A new Raspberry Pi and plenty of toys for it

The Raspberry Pi Zero, since its launch, has been one of the most desirable and difficult to find models of the single-board computer. I’ve been interested in having one for the novelty of such a small, yet capable computer, but the propensity for it to be sold out has put me off. However, the Raspberry Pi Foundation recently announced the Pi Zero W, a variant of the Pi Zero with on-board Wi-Fi and Bluetooth in the same form factor, although with a price of $10 rather than $5. Since adding Wi-Fi and Bluetooth capacity to a standard Pi Zero would generally increase the cost more than the extra $5 equivalent premium that the Pi Zero W has over the Pi Zero on its own and require awkward USB extenders, this appealed to me and I decided to pick one up along with the official case.

Along with the new Pi Zero, I’ve also picked up the standard and NoIR camera modules, a Sense HAT and a Gertduino add-on board to provide the capacity of an Arduino Uno to my Raspberry Pis, especially the older Model B boards that I rarely use any more. As with the electronic components, I’ve only tested these enough to verify that they work, but I’m looking forward to using them when I find the time.

With respect to the Raspberry Pis that I already have, I’ve recently installed RetroPie on a spare microSD card for my Pi 3 Model B. I’ve been impressed by the performance of the Pi when it comes to emulation; even PlayStation games have been smooth on the system, while older systems like the SNES and Mega Drive have worked excellently. I took the system for a spin with some of my friends in a retro gaming night; let’s just say that my Tekken skills could do with a bit of an improvement! Installation of RetroPie is very simple and very accessible as well; after copying the OS image onto the microSD card, everything else on the system is straightforward and it’s possible to copy ROMs and disk/disc images on with a USB drive without any particular effort.