The Kopi Luwak

From Quadshot Wiki
Revision as of 15:00, 21 August 2012 by Jkg (talk | contribs)

(diff) ← Older revision | Latest revision (diff) | Newer revision → (diff)
Jump to: navigation, search

The Kopi Luwak is an amazing platform for controls researcher and hardcore hackers. The Kopi Luwak is assembled and only needs to be bound to your radio transmitter to fly. The main difference between the Kopi Luwak and the other Quadshots is the brain - the Kopi Luwak comes with the Lisa/L and piggy-backed Gumstix Overo® AirSTORM computer-on-module, featuring an ARM Cortex-A8 processor running at up to 1GHz. The AirSTORM can run an embedded Linux OS with realtime kernel extensions, which opens up exciting possibilities for advanced estimation, path planning, and computer vision algorithms.

Important.png The Kopi Luwak requires additional components to fly.

What's in the Box

The Quadshot Kopi Luwak includes:

  • 1x Quadshot airframe (wing with four motor controllers, two servos, two Spektrum 2.4GHz DSM2 satellite receivers, xBee module on serial carrier, and Lisa/L board with Aspirin IMU mounted on flat carrier)
  • 1x Gumstix Overo AirSTORM COM and accessories
  • 2x Winglets
  • 4x Pylon assemblies (pylon, motor, motor clip, propeller saver, 2x M3 propeller saver screws)
  • 3x 8045 normal-rotation propellers
  • 3x 8045R reverse-rotation propellers
  • 1x Lithium-polymer flight battery
  • 1x Battery bay lid
  • 1x Spare receiver receiver bay cover
  • 1x Parts bag containing:
    • 1x xBee module
    • 1x USB xBee carrier board
    • 1x Kopi Luwak receiver bind plug
    • 4x Propeller saver rubber bands
    • 1x cyanoacrylate glue

Quadshot Kopi Luwak showing electronics enclosure - flight battery at top; Lisa/L with Aspirin IMU mounted on flat carrier and LED driver board at lower left; xBee module mounted on serial carrier at lower right.


The Lisa/L is the most powerful autopilot in the Lisa range. It adds a differential pressure sensor to be used with a Pitot tube as well as Overo Gumstix piggyback capability for heavy airborne processing.

Lisa/L is based on the 64-pin STM32F103RE processor featuring 64k of RAM and 512k of FLASH. All the pins are exposed, providing access to the complete set of the STM32 peripherals.

  • Width: 50mm
  • Weight: 30g
  • Length: 90mm

Power supply

The design features a pair of two amp switching power supply modules, one on 5V for external peripherals (like modems, servos, USB webcams or wifi sticks) and one on 3.3V for the rest of the avionics. A third linear supply is available for providing clean power to inertial sensors.


In brief, the STM32 features 3 USARTS, 2 SPI, 2 I2C, 1 CAN, a plethora of timers, ADCs and a generic DMA able to serve all of them. On the board, a number of the communication interfaces are level shifted with user selectable voltage to allow interfacing with all kind of peripherals.

Pressure sensors

The board is equipped with a pair of pressure sensors, one absolute to measure altitude and one differential to measure airspeed. The sensors are amplified and low passed before being sampled by a pair of 16-bit ADCs.

The absolute pressure sensor is the freescale MPXx6115 and the differential one is the MPXv5004DP.


This chip is central to communication with the board during software development. It provides JTAG on the STM32 and SERIAL/USB conversion for the Overo® console. It is powered by the USB bus and hence unpowered while in flight.

Gumstix Overo®

The Gumstix Overo® is a single board computer module piggybacked onto Lisa/L. It communicates with the STM32 through SPI, offering throughput up to 48Mbps and served by DMA on both sides. Exposed peripherals comprise two level shifted UARTs and two USB controllers (one Host and one OTG).

The Kopi Luwak ships with the Sitara AM3703-based AirSTORM COM, but is compatible with the full range of Gumstix Overo® modules.

AirSTORM COM Specifications

  • Architecture: ARM Cortex-A8
  • Temperature: Built with components rated 0C < T <85C
  • Processor: Texas Instruments Sitara AM3703 processor, ARM® Cortex™-A8 Core
  • Processor Speed: Built to operate at 1 GHz
    • Gumstix currently recommends 800MHz for reliable performance
  • RAM: 512 MB
  • NAND: 512 MB
  • Bluetooth
  • 802.11 b/g
  • 1x 27-pin Hirose camera connector
  • 1x microSD card slot
  • Weight: GS3703A @ 5.6g
  • Length: 58 mm
  • Width: 17 mm


We designed the Quadshot’s airframe to be lightweight, yet durable. It consists of a one-meter (39 inch) wing, four pylons with motors and propellers, an enclosure for the electronics, and a standard threaded mount suitable for a small camera. The wing is made out of EPP foam, with a carbon-fiber spar for strength. The pylons are plastic-reinforced foam, and act as landing gear, motor mounts, and tailfins. They are set farther apart on the bottom of the wing to give your camera a clear view.

Additional Necessary Components

To fly, the Kopi Luwak requires a radio transmitter compatible with the included Spektrum® DSM2 "satellite" receivers (SPM9545 or similar). Note that a main receiver (e.g., with servo outputs) is not necessary, as the remote receivers plug directly into Lisa, which decodes their output.

Other radio systems may be compatible with Lisa but may require modification, software configuration, and/or additional components to function.