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Group-buy site launches 40Msps BeagleBone ADC cape

Jul 27, 2016 — by Eric Brown — 1,140 views

[Updated: July 28] — Crowdfunding and group-buying site GroupGets has launched a $79, open source “PRUDAQ” BeagleBone ADC cape with 40Msps analog input capabilities.

Launched in 2014 in Santa Barbara, Calif., GroupGets LLC is both an embedded device manufacturer and a crowdfunding group buying platform for buying existing hacker gear. The group buying platform part of the business specializes in offering products that are not available in under 1,000-unit quantities in smaller quantities including single units. Some products are available as such, but GroupGets can get discounted prices via group sales. GroupGets has already completed 94 campaigns, and has 11 active campaigns, including its latest: a digital acquisition BeagleBone cape called the PRUDAQ.

Two views of the PRUDAQ cape stacked on a BeagleBone Black
(click images to enlarge)

While most of GroupGets group buying offerings are from third parties, the company built the PRUDAQ itself under its GetLab label. The fully open source device was designed by Google Research, which recently posted full specs and schematics.

Single unit pricing is $79 for the PRUDAQ, and there’s also a kit that includes a BeagleBone Black SBC along with accessories. Each new GroupGet product has a minimum reservation requirement in order to “fund,” and a maximum quantity that will be made available if funding occurs. In this case, those numbers are 10 and 50, respectively, so with 7 units currently reserved the PRUDAQ is listed as 70 percent funded.

See farther below for more on GroupGets LLC’s business model, as well as other GroupGets offerings including a Flir Lepton thermal camera kit for the Raspberry Pi 3 and two Linux-driven drones from Dronesmith Technologies. We also cover some of GroupGets own GetLab labelled products.

PRUDAQ details

Designed by Google Research with a software collaboration from BeagleLogic cape creator Kumar Abhishek, the GetLab PRUDAQ is a data acquisition cape that works with the BeagleBone Black or BeagleBone Green. As the name suggests, the open source add-on supports sampling rates of 40Msps (million samples per second) The board runs on an Analog Devices AD9201 ADC, which can sample two inputs simultaneously at up to 20Msps per channel.

(click image to enlarge)

The name also gives a clue as to how this process is controlled on the BeagleBone. The firmware includes embedded code for the BeagleBone’s programmable real-time units (PRU), and pulls the data into the CPU for processing and storage.

According to the July 20 Google Research blog announcement, the PRUDAQ is designed as a middle alternative between expensive, large, and power-hungry DAQ boards (such as, for example, Data Translation’s Linux-driven, $1,195 DT7816) and an Arduino-based solution. Arduino-based DAQs are small and affordable, but are “slower and have enough RAM for only milliseconds worth of high speed sample data,” says Google Research.

BeagleLogic cape
(click to enlarge)

The Raspberry Pi was given consideration, but Google Research chose the BeagleBone on the strength of its PRUs, which can access all 512MB of the BeagleBone’s system RAM. “This lets us dedicate the PRUs to the time-sensitive and repetitive task of reading each sample out of an external ADC, while the main CPU lets us use the data with the GNU/Linux tools we’re used to,” says Google Research.

Other code stored on a microSD card lets you integrate the device with the BeagleLogic 14-channel logic analyzer cape, which also taps the BeagleBone’s PRU. The Linux-driven BeagleLogic can be used to analyze in-situ over 30 digital protocols including, I2C, SPI and ARM ITM. Abhishek is offering the first round of customers a 10 percent discount on the next generation BeagleLogic model when it becomes available.

Specifications for the PRUDAQ include:

  • Dual-channel simultaneously-sampled 10-bit Analog Devices AD9201 ADC
  • Up to 20Msps per channel (40Msps total) theoretical
  • Powered via USB-powered BeagleBone headers, with 0-2V input voltage range (DC coupled)
  • 4:1 analog switches in front of each channel for a total of 8x single-ended analog inputs
  • SMA jacks for direct access to the 2x ADC channels
  • Flexible clock options:
    • External input via SMA jack
    • Internal onboard 10MHz oscillator
    • Programmable clock from BeagleBone GPIO pins
  • Samsung 64GB USB 3.0 drive (MUF-64BB/AM) for storage of samples
  • Fully exposed, top-mounted BeagleBone headers for connecting or stacking more electronics or another cape
  • Dimensions — 87 x 56mm
  • Weight — 29 grams

Other GroupGets products

Because all of the GroupGets products are already shipping — usually quite recently — there’s no fear of scam projects or of not receiving the product due to delays and other problems, says GroupGets. The site also appeals to environmentally-minded buyers who can afford the volume prices, but don’t want to have to try to resell unused devices or throw them away.

Members can suggest a desired product to GroupGets, which finds and recruits others online with the same purchasing interests. The company also promises to securely handle the campaign target’s fund collection, purchase, and distribution to all campaign backers no matter what their location. Companies offering up a device for sale can usually gain more income without having to hassle with single-unit orders, says the company. If user-initiated campaigns are not otherwise selling the products in single units, they receive a cash bonus of 1 percent.

In addition to the PRUDAQ, other active campaigns range from a $20 UV-LED gizmo and $116 ambient light kit all the way up to a $5,148 DJI Zenmuse XT thermal imaging system. There’s also a $194 MEMs u-spectrometer, a $289 PureThemal 1 set of FLIR Lepton accessories, a $3,600 Squink Multilayer PCB Printer, an $869 Verrado Electric Drift Trike, and an $89 Hide a Horse sawhorse.

Dronesmith Technologies QL25 quadcopter (left) and the Linux- and Edison-driven Luci flight controller inside
(click images to enlarge)

Dronesmith Technologies is offering two Linux-driven drones for sale: a hackable, $420 QL25 DIY quadcopter, and a $4,600 QKII research drone. Both devices incorporate Dronesmith’s Luci programmable flight controller which combines an STM32F427 Cortex M4-F flight management unit (FMU) with an Atom-based Intel Edison module based co-pilot running Linux.

In addition to the group-buy products, GroupGets also builds and sells a number of products in single units the old fashioned way. Unlike the PRUDAQ, most of these GetLab-labeled products are not available for group buys.

Like some of the group-buy products, most of the homegrown GetLab products are board-level accessories for the FLIR Lepton longwave infrared (LWIR) thermal imaging camera. For example, there’s a $109 PureThermal 1 Smart I/O Module, which is part of the aforementioned PureThermal 1 kit.

GroupGets GetLabs products include the PureThermal 1 Smart I/O Module (left) and the Raspberry Pi 3 FLIR Lepton Dev Kit
(click images to enlarge)

Like the PRUDAQ, the FLIR Lepton imager can be used with the BeagleBone Black or BeagleBone Green, among other platforms. GroupGet itself sells a $199 Raspberry Pi 3 FLIR Lepton Dev Kit under the GetLab label.

Further information

The PRUDAQ cape is available at GroupGets for $79 by itself, or $159 in a bundle that includes a BeagleBone Black and accessories. More information may be found at the GroupGets LLC’s PRUDAQ and PRUDAQ bundle product pages. For additional details visit the GitHub PRUDAQ wiki and the Google Research blog’s PRUDAQ announcement.

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