This is part of one of an in-progress series on the SensorTile.box — a nifty development and evaluation tool from STMicroelectronics. This article provides a quick overview of just how much ST has managed to fit into a diminutive box, and takes a look at the sensors shoehorned into the device.
There's always more than one way of doing something.
Having said that, there's not always more than one smart way of doing things.
When it comes to sensing, there are a myriad approaches to inferring your data from the world of inputs available to you.
If you're looking at detecting physical motion, do you want an accelerometer or a gyroscope?
Perhaps you want to detect sound — but what frequency range are you after? For lower frequency response, sometimes a pressure sensor can give better response than a MEMS microphone!
Temperature and humidity are hot topic metrics right now, often associated with comfort levels and air quality — but they are usually plagued with poor integration within enclosures, etc.
Wouldn't it be nice if there was a Swiss Army knife of sensors, a toolbox of tricorder elements that you could just throw at your sensing problem to see what sticks, and what device gives you the data you so sorely desire?
STMicroelectronics seems to have had a similar thought, leading to the development of the SensorTile.box (aka STEVAL-MKSBOX1V1) — a ready-to-use box of tricks, packed full of tried and tested sensor offerings from the company.
Delivered as a discrete, diminutive blue box, there's a huge amount more to this development kit than first meets the eye!
If you've ever browsed Reddit, you'll know that one does not simply post a picture of the box, without following up — not unless you want to keep your karma in check, that is. Unlike Reddit — and the typical empty boxes found there that tease and tantalize us — there's quite a lot in this box, so we'd best take the time to have a bit of a look around inside to ensure we don't miss anything!
If we take a screwdriver to the two fixing screws of the enclosure, we are soon rewarded with the sight of the PCB assembly inside, and oh boy, is there a lot going on here! Technically, this isn't the first thing we see, with this side of the PCB orientated into the lid of the box, but we're starting here because, well, just look at it! There's just so much to talk about..
Crammed onto the front side of this PCBA are a bevy of sensors for you to play with; there's something for everyone — and every measurement — on this board; you're very likely to find what you're looking for, even if you haven't quite worked out the sensor solution that your are seeking!
It's no overstatement to say that ST has really sought to showcase as much of the product range as is reasonably possible to squeeze into such a small space.
- Digital temperature sensor (STTS751)
- 6-axis inertial measurement unit (LSM6DSOX)
- 2 x 3-axis accelerometers (LIS2DW12 and LIS3DHH)
- 3-axis magnetometer (LIS2MDL)
- Altimeter / pressure sensor (LPS22HH)
- Microphone / audio sensor (MP23ABS1)
- Humidity sensor (HTS221)
With such a slew of sensors sitting in standby, waiting for your signal processing, you'd hope that there is a suitably slick MCU on this board, ready to make sense of your sensor data stream — and you'd be in luck! ST has chosen to include an ultra-low-power MCU, which doesn't skimp on the spec sheet!
The on-board ST STM32L4R9 is a beefy Cortex-M4 MCU, complete with the DSP and FPU hardware that the M4 range is commonly favored for, while also keeping tabs on the power consumption.
Core to the operation of the SensorTile.box is Bluetooth Smart connectivity (v4.2), provided by the one of ST's wireless module offerings, the SPBTLE-1S BLE module!
The back of the board is a comparatively sparse affair, with little more than a selection of tactile switch buttons, the requisite programming and debug headers for lower-level application development, and an all-important uSD card slot for logging data to your heart's content — and then some!
The only bit of hardware that we haven't touched on so far is still sitting (just about) in plain sight — those red and black wires trailing to the edge of both photos lead to a 500mAh LiPo cell, which is enough to keep this device running for a few days (without any power optimization at the application level). Charging the cell is accomplished via the micro USB connection, meaning that you don't have to worry about disassembling the box each time your charge gauge reads "empty."
Housed within in a robust blue plastic enclosure, the PCBA is protected from potential dents and dings it might otherwise encounter in the course of your experimentation and evaluations — while not compromising measurement ability — the status LEDs are made available through fitted light pipes, and there's a port to allow not only pressure waves to reach the MEMS mic, but to also facilitate gas exchange to the environmental sensors.
ST has actually given a bit of thought as to the use cases for... the case... and thought to include two enclosure backing plates — that level of detail is going above and beyond the mark for a development board — they want this to work for your application!
The standard "tabbed" enclosure plate expands the box profile slightly, to offer two mounting tabs, with holes pre-drilled. If you want to securely mount the SensorTile.box to something, say for effective mechanical coupling — in the case of vibration analysis using the accelerometer devices — this is the way to go about doing so!
The other backing plate forgoes fixing tabs, and instead keeps the box a bit easier to pick up and pocket — ideal for taking it on a walk, if you've wondered about the potential your pedometer application.
If you're like me, and can't resist further modifying things, you might find ways to sacrifice one of the backing plates to more selectively suit your application. I was able to find some small, cylindrical Neodymium magnets in my toolbox — perfect for fitting into some small holes I drilled into one of the plates. Now my box can sit on the fridge door, and serve to alert me when I forget to close it — he built in beeper is long malfunctioned. I have likely severelyoffset my magnetometer data, but as I'm not measuring that for any of my proposed applications, I'm not too bothered by that!
As far as the introduction to the hardware goes, that's awrap! In the next article, we'll take a look at the insane amount of effort ST has put into the software and firmware ecosystem that supports the SensorTile.box.
There's a lot to cover, which is why we're going to do so over the course of a couple posts. In the meantime, be sure to enter for a chance to win a free kit from Avnet.