feature article
Subscribe Now

A Bluetooth/ZigBee Mashup

Freescale’s Kinetis MCUs Offer a Choice of Interface; or No Choice At All

Itching to invent your own electronic door locks? Freescale has the chip for you. Or your new LED lighting project. Or that home-automation system you’ve been meaning to create. If it’s small, cheap, and needs low-energy wireless communications – a trifecta that covers just about everything these days – you may want to look at the new Kinetis.

What’s that? Don’t know about the new Kinetis? You’re forgiven, because Freescale (soon to become part of NXP) has an awful lot of Kinetis chips already, and it’s not easy to keep them all straight. The ones you want to remember this week are called KW20, KW30, and KW40.

Like other Kinetis microcontrollers, these ones are ARM-based chips with a bit of on-chip RAM and ROM, making them standalone devices – if you’re lucky. What makes the new chips different from their Kinetis brethren is their wireless interfaces. The KW20 comes with an IEEE 802.15.4 interface; the KW30 has a Bluetooth Low Energy (BLE) interface, and the KW40 has both.

All three chips have the same ARM Cortex-M0+ CPU running at 48 MHz, so they ain’t fast, but that’s not the point. All three also come with crypto accelerators, an ADC and a DAC, timers, various serial interfaces, a random-number generator, and, surprisingly, a capacitive touchscreen interface. That smorgasbord of goodies is pretty typical among Kinetis chips (indeed, among microcontrollers in general), apart from the wireless interfaces. The 802.15.4 and Bluetooth interfaces make these a bit special. In fact, the KW40 is Freescale’s first Bluetooth Low Energy interface ever.

If you’ve ever implemented a Bluetooth interface, you know that it’s an insanely complicated standard. For all of their apparent simplicity, Bluetooth and BLE are remarkably complex under the hood. That’s why you want a dedicated MCU handling the protocol stack for you, and Freescale obliges by supplying all the software/firmware you’ll need to make the KW30 or KW40 jump through the appropriate hoops.

Conversely, 802.15.4 is… not like Bluetooth. Like a lot of IEEE standards, 802.15.4 is a “half standard.” That is, it defines the physical layers of the interface (even though “physical” seems oddly out of place with a wireless standard), but not the logical layers above it. That’s why it’s been incorporated as part of several other standards, most notably ZigBee. At any rate, 802.15.4 is a handy starting point for any low-power, short-distance, low-data-rate wireless communications protocol. You could even invent your own. That’s what the KW20 or KW40 are for.

Why would you want both wireless interfaces on the same chip? Isn’t that just hedging your RF bets? No, Freescale believes there is a category of gadgets that really do need both at the same time. An electronic door lock, for example, may use BLE to talk to the customer’s smartphone acting as a remote key fob. But said lock might also be part of a home-automation network, alerting the lighting controller or the thermostat that The Master has returned home.

So why not go whole hog and make a KW50 chip with BLE, 802.15.4, and Wi-Fi? You could talk to almost anything in the world! Yes, but you’d also burn a bit too much energy for the current Kinetis (Kinetii?), and the wee little Cortex-M0+ just really isn’t up to the task. If you want Wi-Fi with your Bluetooth, you’re going to have to do it off-chip. Or just look for a different microcontroller.

The energy thing brings us back to another KW20/30/40 feature: their on-chip DC/DC converters. While most MCUs can operate at fairly low voltages, the new chips make a point of playing nice with coin cells and/or alkaline batteries. The chips include both buck and boost converters, the former tolerating 2.1 – 4.2V, and the latter supporting 0.9 – 1.8V operation. No word on the static-electricity input option.

Prices for these little guys are in the $2 range, and packages are commensurately small. Oddly, the KW30 comes in a smaller package than the other two – a 32-pin QFN instead of a 48-pin package – on the theory that BLE designers are likely creating some sort of wearable device and are therefore obsessive about size and weight. The tradeoff for the skinny package is fewer I/O options, but that’s the deal you make. If you want 802.15.4, you get the larger package and the expanded pinout.

Atmel, Microchip, STMicroelectronics, and even NXP – Freescale’s soon-to-be-parent – make competing MCUs with 802.15.4 interfaces. They’re not hard to find. There are also other BLE-enable devices out there. The new Kinetis triplets aren’t a first for the industry, just a first for Freescale. But that’s still significant because (a) choice is a good thing, and (b) Freescale has some very nice prototyping and support options. A lot of designers just prefer Freescale, and vendor loyalty runs surprisingly strong in this industry. Nothing wrong with that. Now there are no more excuses for putting off that automated LED lock project. 

8 thoughts on “A Bluetooth/ZigBee Mashup”

  1. Pingback: GVK BIO
  2. Pingback: siap ppdb sulsel
  3. Pingback: zdporn
  4. Pingback: DMPK
  5. Pingback: ADME
  6. Pingback: Boliden
  7. Pingback: Diyala Engineering

Leave a Reply

featured blogs
Apr 9, 2021
You probably already know what ISO 26262 is. If you don't, then you can find out in several previous posts: "The Safest Train Is One that Never Leaves the Station" History of ISO 26262... [[ Click on the title to access the full blog on the Cadence Community s...
Apr 8, 2021
We all know the widespread havoc that Covid-19 wreaked in 2020. While the electronics industry in general, and connectors in particular, took an initial hit, the industry rebounded in the second half of 2020 and is rolling into 2021. Travel came to an almost stand-still in 20...
Apr 7, 2021
We explore how EDA tools enable hyper-convergent IC designs, supporting the PPA and yield targets required by advanced 3DICs and SoCs used in AI and HPC. The post Why Hyper-Convergent Chip Designs Call for a New Approach to Circuit Simulation appeared first on From Silicon T...
Apr 5, 2021
Back in November 2019, just a few short months before we all began an enforced… The post Collaboration and innovation thrive on diversity appeared first on Design with Calibre....

featured video

Meeting Cloud Data Bandwidth Requirements with HPC IP

Sponsored by Synopsys

As people continue to work remotely, demands on cloud data centers have never been higher. Chip designers for high-performance computing (HPC) SoCs are looking to new and innovative IP to meet their bandwidth, capacity, and security needs.

Click here for more information

featured paper

Understanding the Foundations of Quiescent Current in Linear Power Systems

Sponsored by Texas Instruments

Minimizing power consumption is an important design consideration, especially in battery-powered systems that utilize linear regulators or low-dropout regulators (LDOs). Read this new whitepaper to learn the fundamentals of IQ in linear-power systems, how to predict behavior in dropout conditions, and maintain minimal disturbance during the load transient response.

Click here to download the whitepaper

Featured Chalk Talk

Mom, I Have a Digital Twin? Now You Tell Me?

Sponsored by Cadence Design Systems

Today, one engineer’s “system” is another engineer’s “component.” The complexity of system-level design has skyrocketed with the new wave of intelligent systems. In this world, optimizing electronic system designs requires digital twins, shifting left, virtual platforms, and emulation to sort everything out. In this episode of Chalk Talk, Amelia Dalton chats with Frank Schirrmeister of Cadence Design Systems about system-level optimization.

Click here for more information