118 lines
6.5 KiB
Markdown
118 lines
6.5 KiB
Markdown
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title = "2020 review of Raspberry Pi alternatives"
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date = 2020-10-06
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tags = ["admin"]
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toc = true
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The Raspberry Pi is a cardboard-computer that lets you run your own operating
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system. Or put it the other way around, an open computer the size of a
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cigarettes pack (depending on what kind of cigarettes you refer to). But it's
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quite a barebone system, mostly lacking proper ADC and DAC, and battery
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management. Extensions allow to stack those features, but they're overall quite
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expensive. It might be time to consider alternatives to the rPi Zero in the same
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... hem league ?
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## rPi Zero features
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The smallest form factor is the Raspberry Pi Zero at 60x32mm. The RPi Zero w is
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a wifi+bluetooth model for a 40% increase in price, topping at ... €11.
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The rPi Zero roughly shares its processor with the initial rPi, that is a
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Broadcom BCM2835 SoC, with an ARMv6 core. Those were the first ARMs to support
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floating point calculations.
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The various available models all lack an ADC and a proper DAC, although most do
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have an audio output that can do CD-like audio quality using PWM modulation -
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that is, pulsing alternative 0s and 1s so quickly it feels like an analog output
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on an average (see [this rPi post][rpi-audio] on rPi audio quality).
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Power management is also quite barebone : you power them through a micro-USB
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port and they can't control a battery's charging state. You can plug a battery
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rescue pack to feed it, but then you will have to charge it separately, and if
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you ever want to craft a case too put it in, this will hardly fit into the same
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proportions.
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Various constructors provide extensions called pHats that stack on the rPi using
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its GPIO pins. If you need a self-contained system with a battery and power
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control, you will need a pHat specialized in power management, like
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[pibat][pibat] that bills $26 for 1600mAh, or [pisugar2][pisugar2], very neat
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but $40 worth for 900mAh. Another interesting extension is the [UPS power
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expansion board][ups], hosting 1Ah for $20. The PiHut also sells a [LiPo
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shim][shim] to keep the functionality packed.
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## Banana Pi M2
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Banana Pi obviously tries to challenge the features of the Raspberry Pi. The
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firm developed the [bPi M2][bpi-m2-wiki] that's a revamped version of the rPi
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Zero, featuring a ARMv7 quad-core processor, and a soft power-on button. It's
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$18 worth at [Aliexpress][bpi-m2].
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## Arietta
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Acme Systems propose the [Arietta][acme-arietta]. This board sports the
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Microchip AT91SAM9G25 processor, based on the ARM926 core, which belongs to the
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ARMv5 series. Acme assures customers that it is guaranteed to run the latest
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linux kernel for quite long. It is supported by the ArchARM distribution. Acme's
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site offers a €25 basic model.
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## NanoPi
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The [NanoPi NEO][nanopi] features an Allwinner H3 processor, with a quad-core
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cortex-A7 ARM core. It's 40x40mm large, and has an ethernet and a USB-A socket.
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It seems able to do basic power management, according to notes in
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[nanopi.io][nanopi.io]. [friendlyARM's wiki][nanopi-wiki] states that the nanopi
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has a builtin audio codec and that it should output sound on the lineout pins.
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Its price is reported between $10 and $50.
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There also is a NanoPi AIR with wifi instead of ethernet and USB sockets,
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available for $20 at [friendlyARM][nanopi-air]. Specs are otherwise similar,
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it's just slimmer.
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## Banana Pi D1
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But then there is the [bPi D1][bpi-d1-wiki]. This challenger is 38x38mm big, and
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ships with an HD camera, analog audio in and out pins, power control management
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and a 3.7V li-ion battery socket, a power switch and a user-definable soft
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button, RTC (basically, a clock that remembers time between boots), a
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microphone, and a CMOS image sensor (I don't even know what this means). I saw
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it at $20 at [Aliexpress][bpi-d1].
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This is really a huge feature pack for such a small package. The question that
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rises is : what will we be able to run on this platform ? The processor is an
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Anyka AK3918, with an ARM chipset the generation just before rPi Zero, and a
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bunch of peripherals as stated in the [specs][ak3918] pdf description. Looking
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into it, I found out it uses the same ARM core (ARM926EJ is an ARM9, which is
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part of ARMv5) as the [Olinuxino][olinuxino] board from Olimex, and the same
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amount of RAM (64MB). The latter is supported in [ArchARM][olinuxino-archarm],
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with a caveat due to the limited RAM : localegen would need swap, so there's no
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UTF-8 support. I wonder if distcc would help here. Mainline Arch linux does
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provide a cross-platform distcc installation : `distccd-alarm-armv5`. But this
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doesn't prove Arch will run on Anyka's chip. ArchARM install instructions for
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various ARMv5 boards imply installing uboot in the boot sector. This should
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work, as it relies on pretty standard settings.
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I don't know what to expect from the audio hardware capabilities either, since
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they're embedded into Anyka's chip, and probably differ from Olinuxino's i.MX233
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chip audio hardware. I'll keep this article up with any information I might get
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on this subject.
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## Conclusion
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The bPi D1 seems to be the most fitted product, but there is no guarantee it
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will run your preferate OS. The NanoPi seems to be the next interesting choice,
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but then you will have to deal with power management. In the end, the rPi Zero
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is still a favorable choice, years and years after its design.
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[rpi-audio]: https://www.raspberrypi.org/forums/viewtopic.php?t=195178
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[pibat]: https://www.ebay.fr/itm/PiBat-Raspberry-Pi-Zero-W-1600mAh-LiPo-Battery-Shield-5-6-Hours-of-autonomy/283842482176
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[pisugar2]: https://www.tindie.com/products/pisugar/pisugar2-battery-for-raspberry-pi-zero/
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[ups]: https://www.alibaba.com/product-detail/Raspberry-Pi-Zero-UPS-Power-Expansion_62093794216.html
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[shim]: https://thepihut.com/products/lipo-shim?ref=isp_rel_prd&isp_ref_pos=2
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[nanopi]: https://www.alibaba.com/product-detail/Open-Source-H3-Quad-core-Cortex_62093676606.html
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[nanopi.io]: http://nanopi.io/nanopi-neo-air.html
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[nanopi-air]: https://www.friendlyarm.com/index.php?route=product/product&path=69&product_id=151
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[nanopi-wiki]: http://wiki.friendlyarm.com/wiki/index.php/NanoPi_NEO_Air#Custom_welcome_message
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[bpi-m2-wiki]: http://wiki.banana-pi.org/Getting_Started_with_M2_Zero
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[bpi-m2]: https://www.aliexpress.com/item/32839074880.html
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[bpi-d1-wiki]: http://wiki.banana-pi.org/Banana_PI_D1
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[bpi-d1]: https://www.aliexpress.com/item/32240699956.html
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[ak3918]: https://drive.google.com/file/d/0B4PAo2nW2KfnbGJpa19FWWpwWDQ/view
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[olinuxino]: https://www.olimex.com/wiki/IMX233
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[olinuxino-archarm]: https://archlinuxarm.org/platforms/armv5/olinuxino
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[acme-arietta]: https://www.acmesystems.it/arietta
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