Category Archives: Coding Guides

Z-Wave Summit 2017 at Jasco in Oklahoma City

“IoT Device Testing Best Practices” by Eric Ryherd

Summit1Click HERE to see the entire presentation including my notes. If you are a Z-Wave Alliance member a video of the presentation is usually posted on the members only section of their web site. The main takeaways from my presentation are:

  • Have a written test plan
  • Use the Compliance Test Tool (CTT) as the START of your test plan
  • Vary the environmental conditions during testing
  • Test using real world applications
  • Test using complex Z-Wave networks with routing and marginal RF links
  • Test with other hubs and devices
  • Automate testing using tools like the ZWP500
  • Code firmware with failure in mind
  • Utilize the WatchDog timer built into the Z-Wave chip

ZWaveSummit2017aThe presentation goes into detail on each of these topics so I won’t duplicate the information here. I also go thru several failures of devices I’ve been working with. You learn more from failures than you do when everything just works. Feel free to comment and let me know what topic you’d like to see for next years summit.

Z-Wave Summit Notes

One of the main purposes of the summit is to learn what’s new in Z-Wave and what Sigma is planning for the future. The most important news at this year’s summit is SmartStart. The goal for SmartStart is to simplify the user experience of installing a new device on a Z-Wave network. The concept is that a customer will open the package for a device, plug it in, the hub is already waiting for the device to be joined and the device just shows up on their phone without having to press a button or enter the 5 digit pin code. This is a “game changer” as Sigma pointed out many times during the summit. Typically a user has to put their hub into inclusion mode, read the product manual to determine the proper button press sequence to put the device into inclusion mode, wait for the inclusion to go thru, write down the NodeID number, with an S2 device they have to read the teeny-tiny 5 digit PIN code printed on the product (or scan the QR code) and then MAYBE the device is properly included. Or more often, they have to exclude and retry the process all over again a couple of times. SmartStart as you can see will make the user experience much easier to get started with Z-Wave.

SmartStart enables “pre-kitting” where a customer buys a hub and several devices as a kit. The hub and the devices in the kit are all scanned at the distribution warehouse and are all white listed on the hub web site. When the customer plugs all the devices in, they automatically join and all just magically show up ready to be used without the frustration of trying to get all the devices connected together. Unfortunately there are no devices that support SmartStart and there are no hubs that support it either – yet. We’ll get over that eventually but I suspect it’ll take a year before any significant numbers of SmartStart supported devices show up on Amazon.

SmartStart is enabled in the SDK release 6.81 which occurred during the summit. There are some other handy features in this release. The main new feature (after SmartStart) is the ability to send a multi-cast FLiR beam. One problem with FLiR devices is that they are all sleeping devices and briefly wake up once per second to see if someone wants to talk to them. Prior to 6.81 you had to wake up the devices one at a time and each one would take more than one second to wake up. If you have battery powered window shades like I do, there is a noticeable delay as the shades start moving one at a time instead of all together. Both the shades and the remote (or hub) will need to be upgraded to 6.81 before we can use this new feature. That means it’ll be again probably another year before this feature is widely available, but it’ll get there eventually.

At CES in January Sigma will be announcing the newest generation of the Z-Wave transceiver chip, the 700 series. The long awaited upgrade from an 8-bit 8051 CPU to a more capable 32-bit ARM CPU will make it much easier for developers like Express Controls to hire engineers who can code firmware and thus we’ll be able to bring more Z-Wave products to market in less time. The chip won’t be available until mid-2018 so we have to stick with our little 8-bit CPU for now.

A new web site, Z-WavePublic.com, has been populated with the Z-Wave documentation as well as images for the Beagle Bone Black and Raspberry Pi loaded with Sigmas Z/IP and Z-Ware. With one of these boards and a USB Z-Stick anyone can start developing with Z-Wave without having to sign a license agreement. Nice way to get started with Z-Wave for you DIY nerds out there. There were many other presentations on Security S2, Certification, The CIT, Z/IP, HomeKit and many other topics on the technical track of the summit. The marketing track had a different set of presentations so I recommend sending both a technical person and a marketing person to the summit.

Summit isn’t all work, work, work

IMG_20170927_090355The Summit isn’t all work all day though the days are long and tiring. Tuesday evening was a reception at Coles Garden which is a beautiful event venue. Unfortunately it was raining so we couldn’t wander thru the gardens much but Mitch, the Alliance Chairman, kept us entertained.

Wednesday evening was the Members Night at the Cowboy museum. Oil profits made a lot of wealthy Oklahomans who were able to make sizable donations to this huge museum. There is a lot more to see than we had time to explore so I’d recommend spending more time here if anyone is visiting Oklahoma City. Lots of food and drink made for an ideal networking environment with your fellow Z-Wave developers.

 

10 Questions when Reviewing Embedded Code

Design News posted a great article “10 Questions to Consider When Reviewing Code” and I’m just posting the list here. Follow the link for the full article with the details behind each question.

  1. Does the Program build without warnings?
  2. Are there any blocking functions?
  3. Are there any potential infinite loops?
  4. Should this function parameter be a const?
  5. Is the code’s cyclomatic complexity less than 10?
  6. Has extern been limited with a liberal use of static?
  7. Do all if…else if… conditionals end with an else? And all switch statements have a default?
  8. Are assertions and/or input/output checks present?
  9. Are header guards present?
  10. Is floating point mathematics being used?

My personal pet peeve is #3 – I am constantly reviewing that uses WHILE loops waiting for a hardware bit to change state. But what if the hardware bit is broken? Then the device is DEAD. Always have some sort of timeout and use a FOR loop instead of a WHILE loop. At least the code will move on and won’t be dead. Maybe it won’t work properly because of the broken hardware but at least the device can limp along.