Written by  on January 2, 2015

NETGEAR has been selling a line of cute little Internet camera systems called VueZone for a couple of years now. Actually, NETGEAR is known for WiFi access points and small Ethernet switches and routers, and they acquired a San Diego firm Avaak to get the camera product line.

The way the setup works is that several tiny battery-operated cameras talk wirelessly to the central base station plugged into the home Internet gateway, like a cable modem. VueZone uses same 2.4GHz ISM (Industrial, Scientific and Medical) band  as does WiFi, Bluetooth, and some cordless phones. A proprietary signaling scheme is likely used, to optimize power consumption of sending video frames to the base station.

AssemblyThe electronics come in a tight package, with a camera assembly connected via a flex cable to the PCB, as does the small motion detection circuit. The central processor is Texas Instruments MSP430F5524, a low power 25MHz 16-bit processor with 64K Flash and 6K SRAM, $5.50.

PCBWireless connectivity is provided via Nordic Semiconductor nRF24L01, a low power 2.4GHz RF transceiver, $2.20. There is also Cypress CY62138CV30LL 2Mbit SRAM, $3, and Xilinx XC2C32A, $1.60. Component selection of the camera assembly and the motion detection circuit warrant a second look.

BatteriesThe mechanical design is neat, though it looks like a puzzle when one tries to put the thing back together.  In the end, the pieces did fit, and were all accounted for. The sliding power switch and the battery door lock are somewhat of a kludge, though they do mostly work. The magnetic mounting semi-sphere is brilliant and gimmicky. Pretty cool, in the end.

One design choice was to use two 3V “Lithium” batteries, in parallel, whether because of discharge characteristics or physical dimensions, Shorter but fatter than AA, these batteries are known as 123 and built with the LiMnO2 chemistry. Rated at 1500mAh, they are used in cameras and medical equipment, but despite the word lithium in the title, they are not rechargeable. And 123 batteries are not cheap, with the Energizer EL123 at least $1.50 in bulk. A comparable quality alkaline AA Energizer E91 is $0.50 each in bulk.

BasestationThe base station has several lights and a button used to put the unit in the state to ‘pair’ with the camera. Not surprisingly, the base station runs off a wallwart and connects to the main Internet router via Ethernet. I would like to see what processor was picked for the job of encapsulating the video stream, before sending it to the server. But, I could not pop the case open and punted in the end. If anyone cares, let me know and I’ll take a saw to it.

Netgear recently revamped their VueZone offering, eliminating the four camera setup and raising prices on other configurations. This is perhaps in preparation for switching over to a brand new and incompatible system, an HD camera set named Arlo and priced at $350 for a two camera configuration. Fortunately, there is a brisk trade in VueZone combos and individual pieces, used or nearly new, on eBay. I picked-up the two camera setup for $75, in brand new condition. A bargain one can enjoy with a cup of gourmet coffee.

SkyBell Video Doorbell

Written by  on January 1, 2015

V-2 RocketLooking through a camera at what’s happening outside was first done by Nazis in 1942, to keep an eye on the immense V-2 rockets. Now, you too can look outside, and using your smartphone. Something that Nazis could not do.

And your camera will be inside the doorbell, so you can see people at the door, particularly their index finger. Video doorbells, the WiFi ones, have been attempted for several years now. DoorBot raised $1 million from VCs over two years ago, and is finally shipping, having been re-branded as Ring. And there’s been crowdfunded Chui, i-Bell, Smartbell, etc.  They look different but somehow they all cost $199 and work with an iPhone.

A big reason for placing an outdoor surveillance camera in the space of a regular doorbell is that the two wires coming out of the wall carry 16-24V AC, from a transformer rated at 10-30VA. Just think of the doorbell buttons that glow yellow. While WiFi provides wireless data connectivity, getting power outside does take an effort. Bringing power from inside requires drilling the wall. An outdoor outlet with a wallwart and a long cable would at best be unsightly and potentially hazardous. Batteries would run out eventually or get destroyed in particularly hot or cold weather, and the unit would have to be removed to install new batteries.

One camera doorbell is actually shipping and was well  received – SkyBell. On Indiegogo they raised a hefty $600 thousand two years ago. So, let’s look at what’s inside.

The plastic cover comes off after removing one tiny Allen screw. Not surprisingly, the PCB is round and has a camera setup hanging off it. The main processor is ST Microelectronics STM32F407 in LQFP 100 pin package.  This little embedded monster sport a 32-bit ARM Cortex-M4, running up to 168MHz, with 1MB of Flash. Some of the peripheral options include USB and Ethernet MAC, in addition to the usual UART, SPI, I2C.

STMF407The STM32F407VGT6 part is around $10.* They could have used a lower end part, with an ARM M3 processor, at 120MHz and no FPU, like STM32F217VG. But in the same package and memory size, the price quote is about the same between the two devices. As to power consumption, SkyBell is running wired. But if power consumption were a concern, these parts are not particularly low power. Full on, at 168MHz the ‘407 takes 93mA and ‘217 at 120MHz takes 61mA. A low power ARM processor Stop mode, that retains SRAM but has peripherals off, can get below 0.5 mA nominal.

Despite having all kinds of power from the doorbell transformer, SkyBell includes a 300mAh Lithium Ion battery (about $1 on Alibaba in quantity). If the idea behind the backup battery was for the device to stay up through a short power outage, the WiFi AP and the router would likely be down during an outage anyway and SkyBell has no local storage.

AntennaIncluded is a Linear Technology LT3990 power regulator, over $3. WiFi is implemented via a leadless QFN package with no clear manufacturer markings.  A U.Fl cable connects it to Taoglas FXP74 external antenna, $6.

Video is implemented via OmniVision OV7740 1/5″ CMOS VGA image sensor, which is $5-10 with a lens on Alibaba. Plus Conexant CX93510-11Z VGA JPEG encoder with 128K frame buffer, $6. A flex cable connecting the two says 650nm. The lens is marked ZXZ001.

BackThe PCB is unevenly smeared with some goop, which would offer no protection against the elements. The back plate attaches to the (stucco) wall with two screws. This $199 device is conveniently located within easy reach, to be pried off with a screwdriver and ripped out in two seconds flat. The plastic case with loosely connected lens assembly and the button will not withstand a good punch. The rain can get in from several places in the back, as there is no provision for even a simple moisture seal. I suppose, a good amount of silicon caulking inside and around the rim of the unit could offer some protection.


* Prices are planning estimates, according to Octopart, quantity 10K.