The last LeMaker product I reviewed was the Banana Pro back in July 2015, and if you thought the Chinese-based electronics company had finished drawing inspiration from the Raspberry Pi Foundation when it dropped the ‘Banana Pi’ branding, the Guitar will soon disabuse you of that notion. Based in no small part on the Raspberry Pi Compute Module, the Guitar serves to fill a gap in the market, being an affordable computer-on-module (COM) in a 204-pin SODIMM form factor.
So far, so Compute Module. However, while the Raspberry Pi Foundation has been slow to replace the Compute Module’s aging single-core ARMv6 BCM2835 system-on-chip processor, the Guitar boasts a quad-core ARMv7 chip running at up to 1.3GHz, sitting alongside a PowerVR SGX544 graphics processor. There’s also 1GB of DDR3 memory included on the SODIMM module itself, along with a combined audio and power management unit and 8GB of on-board flash storage. That’s a lot of hardware, and the footprint suffers for it.
While the Compute Module is roughly the same size as a standard DDR3 memory SODIMM, the Guitar is a fair bit longer, measuring 68 x 44 x 5mm. The Compute Module’s benchmark results are around ten times slower than those of the Guitar, though, completing a SysBench run in around 500 seconds, compared to just 51.6 seconds for the Guitar, and the Compute Module has no on-board storage at all.
So, the Guitar is faster but bigger. It also boasts a more impressive baseboard than the one provided with the Compute Module: as well as micro-SD support for storage expansion, it includes HDMI 1.4a video and audio, analogue video and audio, two USB 2 ports, one USB 3 OTG port, an infrared receiver, a camera and even an on-board microphone. There’s also a 10/100Mb/sec Ethernet port and a 2.4GHz 802.11a/b/g Wi-Fi and Bluetooth radio module, both of which are provided by the baseboard and are absent from the module itself. Their performance is poor though – the small chip antenna used for wireless communication struggles with weaker signals, while the theoretically 100Mb/sec-capable Ethernet port maxed out during testing at a less than impressive 32.11Mb/sec.
The processor, though, is a different story. The Actions S500 SoC makes a change from the usual AllWinner parts found on Chinese Pi-alikes, and its four 32-bit Cortex-A9 processing cores easily beat the cores found on the Raspberry Pi 2; while the Guitar completed a SysBench run in 51.6 seconds, the Pi 2 took a more leisurely 74.5 seconds. Sadly, the GPU is a different story. As with other PowerVR products, driver support outside the Android ecosystem is poor. If you’re running LeMaker’s Android 5 build for the Guitar, you’re laughing; any other Linux distribution, though, requires you to manually install accelerated drivers that were built using Imagination’s driver development system – a process which I spectacularly failed to complete, despite following LeMaker’s detailed instructions on the official company wiki site, leaving the Guitar failing to display an image from its HDMI port.
This problem isn’t unique to the Guitar, though, and there are still legitimate reasons to pick up LeMaker’s latest design over the many alternatives on the market now. Anyone whose projects are CPU-limited will enjoy a noticeable speed boost over a Raspberry Pi 2 at roughly the same overall cost, and with the familiar 40-pin GPIO header with 28 pins user-accessible for general-purpose programming. Meanwhile, anyone who has been working to develop their own Compute Modulebased design should theoretically find it easy to switch over to the larger but more powerful Guitar.
The traditional reason for opting for a third-party board has been broader compatibility. When the Raspberry Pi family was stuck on the outdated ARMv6 architecture, operating system compatibility was limited; the ARMv7 Raspberry Pi 2 changed that situation, introducing the ability to run platforms as diverse as Ubuntu and Windows 10. The biggest advantage of the Guitar in this respect is a functional Android 5.0 image, which the Pi still lacks. There are also modified Debian Jessie images in the form of Lemuntu and LeMedia, with the latter booting into the Kodi media player and the former into an LXDE desktop with applications including the IDLE Python environment and AbiWord word processor pre-installed. There are Arch, and Ubuntu MATE images available too, but it’s only the Android image that really sets the Guitar apart from the competition.
However, the biggest factor in the Guitar’s favour is its price. Despite the Compute Module’s poor performance, its target market has always been professional engineers looking to prototype commercial implementations, and the pricing reflects that aim. The Compute Module and baseboard bundle will set you back an eye-watering £80 inc VAT. The more powerful Guitar, by contrast, is available from its official stockist, www.lenovator.com, for $44.90 (around £30) – a considerable saving for switching away from the comfortable and familiar Raspberry-themed ecosystem.