Hardkernel ODROID XU4 Shifter Shield Review
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Software Compatibility
The ODROID-XU4 runs Linux – and thus supports the sysfs interface to GPIO.
Initially I had problems using sysfs for I/O, as I normally just use a sudo in front of the cat command for the export – however the XU4 requires using a root shell, invoked either with “su -s” or “sudo su”, before you can export GPIO’s.
Once odroid & mrdjr got me past that hurdle, I was happily blinking LED’s and reading inputs.
A few days later, a port of wiringPi was released, making the rest of my GPIO testing easier.
To install wiringPi for the XU4, execute the following from a terminal:
sudo apt-get update
sudo apt-get upgrade
sudo apt-get dist-upgrade
sudo reboot
then
git clone https://github.com/hardkernel/wiringPi
cd wiringPi/
./build
You can then use the ‘gpio readall’ command to see the current I/O settings and values.
Hardware Compatibility
The ODROID XU4 Shifter Shield has a 40 pin GPIO connector, designed to be compatible with the 40 pin GPIO connector on the ODROID-C1.
The first 26 pins are also electrically fully compatible with 26 pin Raspberry Pi expansion boards.
This means that it is also mostly compatible with the Raspberry Pi A+/B+2 40 pin GPIO header, so I thought it would be interesting to see how Adafruit’s popular 40 pin Raspberry Pi “HAT” would fit on the XU4 Shifter Shield.
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As you can see above, the Adafruit HAT would fit fairly well, assuming that I’d already soldered the female header into it 🙂
Out of the four mounting holes, one does line up – the others could be used with shorter standoffs that would just sit on the Shifter Shield below.
Ok, now that we see how a 40 pin hat would mount, what should we look at next I wonder?
Blinking Lights… everyone needs (and loves) blinking lights!
As soon as I saw the clear GPIO labels silk screened on to the XU4 Shifter Shield, I realized that (shameless plug) my SchoolBoard ][ development board would work great with an XU4 + Shifter Shield.
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In case you are wondering why I put LED’s on the breadboard when there are LED’s on SchoolBoard ][ the answer is simple.
Hardkernel states that the GPIO is only rated to source/sink 4ma, and the SchoolBoard ][ was current limiting the LED’s to 5mA using 470 ohm surface mount resistors.
(I need to order some 1K SMD resistors, then I can offer SchoolBoard ][‘s with super bright LED’s that will draw less than 2mA)
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I was itching to try RoboPi on the XU4, as the XU4 is the fastest ARM single board computer I’ve tested to date, making it a great choice for robots that need more brain power.
RoboPi works great on an XU4 🙂
The serial port is on /dev/ttySAC0, and GPIO#174, once exported, can be used to reset RoboPi. My RoboPi C and Python libraries both worked immediately.
