One of the downside with current smart wearables is that most need to be recharged quite often, every day, week or month, and we’re still a long way of 10 year battery life offered by typical watches. I’m hopefully that eventually many devices won’t need to be recharged at all as we’ll have made improvements both in terms of power efficiency and energy harvesting using solar, body heat, vibrations and other techniques.
Takakuni Douseki, professor at the Department of Electronic and Computer Engineering of Ritsumeikan University, has been working on micro energy harvesting, and his latest “wireless involuntary urination sensor system” notifies the user when it’s time change the diapers without the need of any battery, instead using energy generated by urine and stored in a capacitor in order to transmit the data wirelessly.
The prototype is using a modified baby diaper with a 320x5mm activated carbon piece, and a 1.8mm aluminum electrode placed between the absorbent and a waterproof sheet. The amount of electricity generated increases with the amount of urine, with the current peaking at the time of “release” as shown in the chart below.
All that electricity is stored in a capacitor, and when the amount of urine reaches a threshold level (80 cm3), the system transmits an ID signal over a wireless connection up to 5 meters. The system may be commercialized later for example to care of patients suffering from incontinence. The research paper about urine energy harvesting and self-powered diaper can be found on IEEE website.
Last year Ambiq Micro unveiled their Apollo Cortex-M4F MCU with Cortex M0+ energy efficiency thanks to operation in sub-threshold voltage (< 0.5 V), and the MCU is said found in Matrix Powerwatch, a fitness tracker powered by body heat that you never need to charge. The company has recently announced a new version of the micro-controller with Apollo 2 MCU with better maximum performance thanks to a higher maximum clock speed (48 MHz vs 24 MHz), and higher efficiency (10 μA/MHz vs 30 μA/MHz @ 3.3V).
Apollo 2 MCU key features and specifications:
Ultra-low supply current
<10 μA/MHz executing from flash at 3.3 V
<10 μA/MHz executing from RAM at 3.3 V
ARM Cortex-M4 Processor up to 48 MHz with FPU, MMU, wake-up interrupt controller with 32 interrupts
Ultra-low power memory
Up to 1 MB of flash memory for code/data
Up to 256 KB of low leakage RAM for code/data
16kB 1 or 2-way Associative Cache
Ultra-low power interface for off-chip sensors
14 bit, 15-channel, up to 1.2 MS/s ADC
Temperature sensor with +/-2ºC accuracy
Serial peripherals – 6x I2C/SPI master,1x I2C/SPI slave,2x UART, PDM for mono and stereo audio microphone
32.768 kHz XTAL oscillator
Low frequency RC oscillator – 1.024 kHz
High frequency RC oscillator – 48 MHz
RTC based on Ambiq’s AM08X5/18X5 families
Wide operating range – 1.8-3.6 V, –40 to 85°C
Package – 2.5 x 2.5 mm 49-pin CSP with 34 GPIO; 4.5 x 4.5 mm 64-pin BGA with 50 GPIO
The MCU promises weeks, months, and years of battery life thanks to Ambiq Micro’s patented Subthreshold Power Optimized Technology (SPOT) Platform. Apollo 2 will be suitable for battery operated devices, or even batteryless devices leveraging energy harvesting such as wireless sensors, activity and fitness trackers, consumer medical devices, smart watches, and smart home/IoT devices.
Documentation and devkits are available but you’d need to contact the company to learn more. Ambiq Micro’s Apollo 2 is currently sampling to some partners, and will be sampling more broadly in the coming months. A few more details may be found on Ambiq Micro Apollo 2’s product page.
There are currently several issues with wearables that makes it sub-optimal devices, from displays that can’t be always-on, to unreliable sensors, and in my experience pretty poor reliability, as I’ve managed to go through 4 fitness trackers / smartwatches in a year. Another issue is that contrary to typical watches lasting 10 years with a coin cell battery, most wearables require to be charge every few days, weeks, with the very best devices being chargers every few months. MATRIX PowerWatch promises to solve latter, as you will never need to ever charge it since it charges itself by harvesting energy using your body heat.
The company promotes it as a smartwatch, but it’s closer to an activity tracker, since you can’t keep the Bluetooth LE connection all the time in order to receive notifications to your smartphone. It’s basically used to show time, track your activity and sleep patterns, and you can synchronize the data with your iOS or Android phone when you need it. It does not have to be done often, as the watch can keep up to one year of data. The watch is water-resistant up to 50 meters, and controlled by two buttons (no touchscreen). One extra advantage of the heat body charging mechanism is that it will also allow the watch to accurately track the amount of calories burned, while all other wearables are just making informed guesses. If you don’t wear the watch, a backup battery takes care of power, the watch goes to sleep keeping track of time.
So how does it convert body heat into energy? The company explains:
Our thermoelectric technology converts heat to electric power. It is based on the Seebeck effect discovered in 1821. In the absence of an applied voltage gradient V, electric current, J, can still be generated if there is a temperature gradient, T: . A thermoelectric material must have a low thermal conductivity and high electrical conductivity to function efficiently. NASA has used this technology to power the Voyager spacecraft and Curiosity, the mars rover.
A thermoelectric module is composed of many tiny semiconductor “legs” that when added together create a large voltage.
Some obvious concerns about the technology is whether it will work as advertised in all conditions. It relies on temperature delta, so what happens when the ambient temperature is close to body temperature, would the watch just go into sleep mode in that case, relying on the backup battery? The comments are also interesting, where we learn the display is apparently a black & white LCD display, and not a low power e-Paper display, and some people are starting to ask features like a color display, GPS support, and BT notifications which may not be a realistic goal… But other aspects of the project also inspire more confidence, as they have allegedly tested 1,000 working prototypes, and Arrow Electronics is involved in the manufacturing of the project.
The watch was launched on Indiegogo yesterday, and the project has already surpassed its $100,000 crowdfunding campaign. If you’ll like to get involved you can still go with an super early bird pledge of $119 for the PowerWatch with a nylon strap. Other rewards are just for various quantities up to 100. Shipping is free to the US, adds $15 to the rest of the world, and delivery is scheduled for July or September 2017 depending on the rewards.
Cypress Semiconductor has recently unveiled PSoC 4 L-Series micro-controller family based on ARM Cortex M0 core with more programmable analog and digital blocks, expanded memory, new peripherals and higher number of I/Os, as well as the corresponding Arduino compatible CY8CKIT-046 PSoC 4 L-Series Pioneer Kit to evaluate their latest solution.
PSoC 4200L Block Diagram (Click to Enlarge)
Key features of PSoC 4 L-Series MCU
ARM Cortex-M0 CPU @ 48-MHz with DMA controller, up to 256KB flash, up to 32KB SRAM and up to 98 GPIOs
The quickest way to get started or/and evaluation the new MCU is to get CY8CKIT-046 PSoC 4 L-Series Pioneer Kit with PSoC 4 L-Series pioneer board, a USB standard-A to Mini-B cable, 4 jumper wires, 2 proximity sensor wires, a stereo audio earphone with microphone, and a Quick Start Guide.
Pioneer board specifications:
MCU – PSoC 4200L (CY8C4248BZI-L489) Cortex M0 @ 48 MHz with 256KB flash and 32KB RAM
Storage – 1 Mbit Cypress F-RAM (FM24V10G) + footprint for micro SD slot or serial NOR flash
Wireless Connectivity – Bluetooth 4.1 LE via footprint for EZ-BLE PRoC module (CYBLE-022001-00)
USB – 1x micro USB connector, 1x KitProg USB connector
Audio – 3.5mm audio jack
PSoC 5LP programmer and debugger chip
PSoC 5LP I/O header (2x 8-pin)
PSoC 4200L program and debug header
Arduino compatible headers on main board (left)
Arduino compatible headers on shield board (right)
Digilent Pmod compatible I/O header
Character LCD header
2x CapSense proximity headers
EZ-BLE I/O header
Misc – Current measurement jumper, reset and user buttons, RGB LED, status LEDs, CapSense Gesture pad
5V via micro USB port
Footprint for Cypress Energy Harvesting PMIC (S6AE101A)
After I wrote about SimpleLink Batteryless power switch and receiver, the company decided to sent me a kit to try out by myself. So in this review, I’ll checkout the kit, install a demo to show how it works, and finally have a look at the internals.
SimpleLink Self-powered Power Swtich Kit (Click to Enlarge)
The kit include a power cord with a US plug and a holder and corresponding light bulb that you need to connect to the corresponding red and blue wire of the receiver (white cylinder), and you can control with the green power battery-less switch. Two 3M double face stickers are also included for the receiver and switch, as well as a strap for the switch, a screw set for either the light holder or receiver, and a user’s manual shown below.
Click to Enlarge
Installation is pretty self-explanatory, and you just need to connect the blue and red cables to the input (mains) and output (light) as indicated on the receiver.
Then you just need to connect it the mains (100 to 240V AC), and press the switch to turn the light on and off. You can watch a full unboxing, as well as a two short demos: one close to the receiver, one at around 5 meters starting at 3:11 in the video below.
This works using RF (433MHz) connectivity and in theory line of sight range is 100 meters, and indoors 30 meters, but I found the switch to because unreliable at around 20 meters with line of sight, and if I’m placed at the other side of my house, around 8 meters away, it’s also unreliable through multiple walls at this distance. So it works pretty well, but not exactly as far as in the specs.
I’ve started the teardown by opening the switch.
Click to Enlarge
We can see a thin wire instead the enclosure that is used as the RF antenna. It starts to be a little more difficult to open after, and I broke a few clips.
Click to Enlarge
But the second step shows a rubber pad to cover the board, and a tiny button with a spring. After some more efforts I can finally take the board out.
Lifting the coil revealed ST Micro STM8S103F3P6 8-bit micro controller, and Texas Instruments CC115L sub-GHz RF transmitter. The board name is SimpleLink-V05 MFB20151129.
Finally, I could reassemble everything together, with the switch still working! Yeah! But time to care of the receiver that is much easier to disassemble…
Click to Enlarge
The solder looks thick and clean on the high voltage tracks, so I guess it’s reassuring. The board is called SimpleLinkV4 M&D151129, so both the receiver and switch boards are pretty recent, about one month old. I simply had to pull the board out to check out the other side of the board.
Click to Enlarge
The relay is WRG RJ-SS-112DM1 operating at 12V DC, and supporting up to 10A @ 250V according to the specs. While the board itself is not UL or TUV certified, the relay is said to have some “SSA approval ratings” for “CQC”, cUL, and TUV.
Click to Enlarge
A short wire is again used as the RF antenna.
Click to Enlarge
The long push button and LED are also interesting. The button is used to pair the receiver and the switch in case of issue, but I did not have to use it. The LED turn blue when the light bulb is turned on, and turned off with the light.
Click to Enlarge
The RF board is soldered, and I did not remove it, but I can see two IC, which should be another STM8S MCU coupled with Texas Instruments CC113L smart RF receiver.
I’ll probably use the system with one of my outdoor fluorescent lamp. SimpleLink used to sell the kit on Aliexpress for $48, but they’ve since removed all product from their store. I found the price to be on the high side, and in a world of $3 WiFi modules, I’d expect a receiver + switch kit to be closer to $20 than $50. You can still check out SimpleLink wireless and batteryless switches on the company website.
SimpleLink may be the name used by Texas Instruments for their wireless MCU family, but there’s also a Chinese company called SimpleLink Technology that develops wireless smart home solutions including battery-less power switches that communicate over sub GHz band to receivers using energy harvested from pressing the button(s) on the switch.
They have different models with 1 to 4 buttons, and round and square shapes. Let’s have a look at SIM1010-K1 specifications:
Switch Type – Push-Button; operating force: 7N; typical total travel: 4mm
Number of Keys – 1 gang
Power Mode: Self-Powered
Control Distance – Up to 30 meters indoor (works though walls), 100+ meters outdoor
Frequency Bands – 433/315/868/915MHz
Lifetime – >200,000 times
Connectivity – SimpleLink (most probably entirely unrelated to TI SimpleLink); +10dBm Tx power
Operating Temperature: -25~70℃
Operating Humidity: 0~95%RH
Dimensions – Ф 70 x 15.5 mm
Weight – 44g
That self-powered wireless switch will prevent the need to install cables between the switch and the electrical appliance or light, and communicate with SIM1010-R receiver featuring the following:
Because different country require different certification.
We are applying CE and RoHs certification for basic use, other certification not have now.
We most do OEM order, use customers’ brand, they will do the certification themselves.
Also have some customers do not require certification. ( if not use in big project, to normal customers most do not concern certification )
So it looks like the product has not been independently tested for safety. It does not mean it’s not safe, it just means we don’t know.
Provided you are confident the product won’t be confiscated by the customs due to a potential SimpleLink trademark infringement, and a lack of safety certification, you can purchase a kit of comprised of a switch and receiver for $50 on Aliexpress, and they also have kits with one receiver and multiple switches. More versions can be found on SimpleLink website.
Cypress Semiconductors has recently launched a Solar powered IoT device kit, with the easy-to-remember codename S6SAE101A00SA1002, featuring the company’s CYBLE-022001-00 Bluetooth Smart module, and S6AE101A energy harvesting power management IC (PMIC) on the main board, as well as all accessories such as a small solar panel, a BLE-USB bridge, and all necessary components and cables. Target applications include battery-less wireless sensor node (WSN), IoT device that monitors various sensors, BLE Beacon, wearable device, building energy management system (BEMS), Home EMS, Factory EMSystem, wireless lighting control,wireless HVAC sensor and security system.
The main features of the Energy harvesting motherboard include:
Expansion – Sensor expansion connector with I2C/UART/SPI/GPIO signals
Misc – LEDs for USB power and status, DIP switch for future expansion
Power Supply / Energy harvesting:
Panasonic AM-1801 solar module to harvest light energy as low as 200 lx
Optional external diode bridge to harvest vibration energy (not included)
Optional battery for Hybrid power supply
Dimensions – 45 x 25 mm
Block Diagram (Click to Enlarge)
The firmware supports two modes: Bluetooth Low Energy (BLE) Beacon, transmitting data at 1.5 sec intervals with ambient light as low as 200 lx; and Wireless Sensor Node (WSN), transmitting data at 6 sec intervals with ambient light as low as 200 lx. You can also monitor Bluetooth communication with the BLE-USB bridge provided with the kit, and pre-programmed with custom firmware. This works with Windows 7/8/8.1/10 only.
Click to Enlarge
Documentation include the reference schematic, BOM list, and layout data, as well as a user’s manual, a quick starter guide, and release notes. You can also download the complete DVD (1.1 GB) with all the tools and documentation.
ARM CTO, Mike Muller, showcase imprinted electronics, that is an integrated circuit printed on a plastic film, at ARM TechCon 2015, and several products are featured flexible displays, so in future flexible electronics could bring innovation applications from truly wearables electronics to traceable bank notes, and so on. A company has launched an Indiegogo campaign for a new product, that’s both cool and relatively useless, with ShiftWear sneakers that integrate a flexbile e-Paper display, a battery that recharges by harvesting energy from your steps, and some connectivity (likely Bluetooth LE) to update the display from your iOS, Android or Windows device.
Three models are available: L1, M1 and H1 referring to low height, medium height and high height of the part around the ankle (heel tab?). But all three have basically the same features:
Always-on HD color e-paper flexible display
Up to 30 days of battery life
Waterproof up to 5 meters
Kevlar fiber coated oles
Walk to charge technology
You can display both static images and animation, but battery life will obviously be much better with static images. The shoes are using energy harvesting “walk-to-charge” technology, but it might not be enough to keep the battery charged all the time, so wireless charging is also an option. The Classic version of the shoes are only partially covered with the display. but there’s also a Limited Edition M1 with a display all around the shoe, and limited to 2,000 pieces. There will also be a community to exchange and potentially sell designs to upload to the shoes.
If you watch the video above, you may want to say “just take my money”, but it might be risky because 1. there’s no prototype, 2. launch is only planned for fall 2016, or about one year from now, 3. few technical details are provided, 4. some of the features like HD displays seem tied to a 1 million dollar stretch goal, walk-to-charge to 2 millions, etc.. With that in mind, you could pledge $150, $250, or $350 for respectively L1, M1 and H1 Classic, or splurge $1,000 for a M1 Limited edition. Shipping is not included and adds $25 to North America, and $50 to the rest of the world.