Many development boards are powered over USB, usually via a micro USB ports, and if you have one board, you’d just use a 5V USB adapter with the right amperage, and it will work fine as long as you have a low resistance USB cable (AWG20 cables recommended for higher loads). But when you start to running multiple boards using power strips with USB adapter start to take space, so USB hubs are much more convenient. However, you need to find one that delivers enough power, is reliable, and possible allows per port power control. The guys at LAVA (Linaro Automated Validation Architecture) are using a lot of boards to validate software developed by Linaro and their members, with the boards having to run 24/7, and they had various misfortunes with USB hubs, but as Dave Pigott reports they’ve now found that USB hub of their dream with a 15-port USB hub from Cambrionix which should be their PowerPad 15S model.
- 15x USB port supporting charge and sync with up to 2.1A per port
- 1x USB host port
- Control Interface – Cambrionix API, Terminal Command Session, SSH, Minicom
- Charging Method – Cambrionix VIC “Very Intelligent Charging Protocol”
- Power Supply – 180W external power supply
- Certifications – CE, FCC, Underwriters Laboratory (UL), WEEE and RoHS
Each port of the USB Hub can be controlled individually (charging, syncing, or off modes), allows retrieval of VID/PID data, and records power consumption (amps, charging time, total power consumed). The hub can be monitored and controlled using LiveViewer App for Window or Mac OS, but if you want to automate the USB port, for example to power cycle a board that does not answer to ping request, you may want to use the Cambrionix API available for Linux x86/ARM, Windows, and Mac OS.
When Dave connect the HUB to his (Linux) laptop he noticed it was detected as a serial device only, and after configuring ser2net, he could login via telnet, and help listed a bunch of commands to control each port. As he connected a Hikey boar, he found a command to check all the ports status with their current draw, so he wrote a Python script to control the port as he wanted.
They also found EtherSync Hub from the same company with that’s running Linux, and can be controlled from the network over Ethernet. LAVA team has been running both types of hubs for a while and found them to be reliable, and will update the complete lab with them.
Cambrionix has other USB charging product with various number of ports, and form factor, including a USB charging 1U rack, or a 54-port data transfer USB hub. Check out their products page for details. Those are all nifty USB hubs, but as expected price is pretty high with PowerPad 15 sells for $660 on Amazon US (that’s $44 per USB port), and while there are some other cheaper Cambrionix models on Amazon UK, they probably lack advanced functions like power monitoring. [Update: I’ve been informed model PowerPad 15C (notice the extra C) is much cheaper, as it sells for £159 ex vat (~$200) on Multipad UK. The main difference is that it does not support sync mode compared to PowerPad 15S model].
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