OpenCircuits - User contributions [en]

ARMUS Embedded Linux Board

2007-12-01T18:39:33Z

158.39.243.114: Revert to 13:46, 12 November 2007

==Presentation==
ARMUS, an ARM robotic processing system designed by a team of fourth-year undergraduate students in electrical engineering and computer engineering. This project intends to replace the Handy Board, the current microcontroller system used by first-year undergraduate students in our curricula with a more powerful, versatile and up- to- date technology, while preserving ease of use. Our ARMUS processing system offers high processing and memory capabilities at low energy consumption, for a price of around 300$CAD.

Here is a paper describing the whole project:
[[Media:ArmusPaper.pdf|Article on Armus]]

==Specs==
The board is made to run Linux. We have sucessfully built and tested the first prototype. It ran Linux 2.4 with no big issues. Since then, we have designed the second version (proto2), but never built it because we graduated.
Here are the specs:
* AT91RM9200 CPU (ARM920T core)
* On board 32MB SDRAM and 8 MB Flash.
* CompactFLash
* SD/MMC trough SPI
* 2 RS232 ports
* JTAG/ICE port
* LCD port on the memory bus, we used a graphical LCD of 64x128
* 10baseT Ethernet
* USB Host and Device
* CAN port
* Audio (TLC320AIC23B: stereo out, stereo in, microphone in, 44.1kHz 16 bits)
* 48 IOs and 10 ADCs on a PIC18F8310
* 4x dsPIC30f3010 for motor control (4 DC, 4 servo, 4 capture/compare, 4 quad encoder, 8 more ADCs)

* Power supply is done with two switching power supplies (3.3V and 5V) to minimize power comsuption.

==Design Files==
Here are the whole hardware design tree. These [[Media:ArmusHardware.zip|Project files]] were made using Altium designer 2004 SP4. They include the schematics and the PCB files. I would gladly post a PDF version, but somehow pins number and names get affected by the operations.

There is a free "Altium Viewer" license availlable at www.altium.com, one should be able to view the whole project with it.

Here are the [[Media:ArmusGerber.zip|Gerber files for Armus]], All optimized for Sierra Proto Express, wich did a fantastic job on the first proto run at very low cost with their "no-touch 4-layer" service. To use any other fab house remember that trace/space is 6 mils, and minimum hole size is 15mils.

==Software Drivers and Kernels==
THIS PAGE IS UNDER CONSTRUCTION, COME BACK SOON!
I still need to get the software part together...

== other boards that run Linux ==

* [[Linuxstamp]]
* [http://balloonboard.org/ Balloon board]

[[Category:Projects]]

Motor driver

2007-12-01T18:37:28Z

158.39.243.114: Revert

There are many kinds of motor drivers:
* servo motor controller
* stepper motor controller
* DC motor controller ("brushed")
* AC motor controller ("brushless")
* ... (todo: fill in the other kinds) ...

A DC motor controller that is 'reversible' generally uses an 'H bridge'. This 'H-bridge' uses four output drivers in a configuration that resembles an H where the load is the cross bar in the middle. The lines on either side of the load (the downward strokes in the H) represent a series connection of a pull-up driver and a pull-down driver. This allows each terminal of the load to be connected to either the positive supply rail, or the negative supply rail. This allows a positive, negative or zero voltage difference across the load. This load voltage is then utilized to provide the desired control required of the motor. The various combinations can give a 'forwards' torque on a DC motor, a 'backwards' torque on the same motor, can allow the motor to free-wheel (without any applied torque) or can provide a locking of the motor such that it resists any attempt to rotate it.

A single phase AC motor is generally driven in the same way as a DC motor, however instead of operating the motor drive as a constant DC voltage (in either the 'forward' or 'reverse' direction) the AC motor is driven by an approximation to a sinewave. This approximation is created using the H bridge and driving it with a PWM input such that both the positive and negative voltage periods are the same. This is normally achieved either using a sawtooth waveform compared against a sine wave reference, or is done using a lookup table in a microcontroller.

A similar method is used to drive multiphase (3-phase) AC motors, however instead of just using an H bridge, only a half H bridge is used per phase (3 half-bridges). Each phases half bridge is then driven in the same manner as for the single phase motor, with a phase difference between the phases as appropriate.

Most stepper motor controllers uses 2 independent H bridges (4 half-bridges) for the 2 independent coils of a stepper motor.
Each possible state (one bridge driving current one way, the other way, or free-floating) of both bridges gives 4 "full steps", 4 "half-steps" between the full steps.
The "microstepping" motor controllers use PWM to gradually change in a sine-wave-like manner from adjacent full-steps and half-steps.

((fill in more details here...))

== noise control ==

Many motors make sparks when the brushes make or break contact.
This causes causes lots of electrical noise ("brush noise").
Your TV-watching neighbors won't be happy if you allow this noise to leak out.

"Sparks emit RF energy from DC to daylight as I was once told by an EMC expert."
--
HydraRaptor: [http://hydraraptor.blogspot.com/2007/09/dc-to-daylight.html "DC to daylight"]. More details:
HydraRaptor: [http://hydraraptor.blogspot.com/2007/10/gm3-motor-suppressor.html "GM3 motor suppressor"]

== current sense ==

Often people want to measure the current going through the motor.

There are 3(?) basic techniques:
* low-side current shunt
* high-side current shunt
* magnetic field sense
* ... ''(any others I missed?)'' Yes, [http://www.4qdtec.com/mircl.html pseudo 'mirror' current sensing a MOSFET] -- sampling the voltage across a MOSFET while it is turned on. That voltage is linear with current but varies with temperature. If the purpose of measuring current is to turn off the MOSFET before it overheats, the variation with temperature doesn't matter. (''A true [http://en.wikipedia.org/wiki/Current_mirror current mirror] isn't useful for motors, right?'')
* the "non-dissipative overcurrent protection", a kind of current mirror used in the L6208N ...
* ... ''(any others I missed?)''

Low-side is (electrically) the simplest.

For smaller motors, the current is usually measured by
running the current through a shunt resistor,
and measuring the voltage across the resistor.

In situations where low-side sensing is difficult ( automobile electronics bonded to the "GND" car frame; other systems where it is inconvenient to put a resistor on the "lo" power wire), we turn to high-side sensing.

[http://www.newark.com/jsp/search/browse.jsp;Ntt=high+side+current+sense Newark: high side current sense]; [http://www.digikey.com/scripts/DkSearch/dksus.dll?KeywordSearch&site=US&keywords=high+side+current+sense Digikey: high side current sense]; [http://www.linear.com/ad/current_sense.jsp Linear: current sense circuit collection] (why doesn't this include the Linear LTC6103 ?); [http://focus.ti.com/analog/docs/gencontent.tsp?familyId=57&genContentId=28020 Texas Instruments: "Current Sensor"].

For large motors, the current is measured by running the power wires through a magnetic field sensor -- either
* directly measuring the magnetic field (often with a Hall effect sensor, for example, the Allegro ACS712), which can measure DC and AC current, or
* indirectly measuring the magnetic field with a "one-loop current transformer" (which can only measure AC current).

Because magnetic field sensing is inherently non-contact, it works just as well high-side as low-side.
( [http://focus.ti.com/docs/prod/folders/print/drv401.html "Closed-Loop Magnetic Current Sensor"]. )

== tolerance against software bugs ==

Some motor controller circuits are such that, if the software accidentally sets the "wrong" pins hi or lo, you get a short circuit through the output drivers. This will generally cause a high current to flow, due to the low on state resistance of the output drivers, which may destroy other electronic components before finally blowing the supply fuse.

Other motor controller circuits are such that, if the software accidentally sets the "wrong" pins hi or lo, the worst that could happen is the motor spins the wrong way.
These circuits are designed so that, no matter what the inputs, it is impossible to get a short circuit through the output drivers.
Between "one branch on" and "the other branch on", there is a minimum "blanking time" which has "both branches off". This guarantees that we never have "both branches on" (short circuit).

Guess which type of design I prefer?

== external links ==

A random collection of semi-related links (please prune out the irrelevant ones):

* [http://www.bobblick.com/techref/projects/hbridge/hbridge.html H-Bridge by Bob Blick]
* [http://groups.yahoo.com/group/osmc/ the Open Source Motor Controller Project]
* [http://massmind.org/techref/io/stepper/linistep/ LiniStepper] $30 each; Open Source! Circuit Diagram, PCB (Board) Layout, and PIC Software all available. Nice photos of the LiniStepper at http://www.piclist.com/techref/io/stepper/linistep/lini_bld.htm .
* [http://massmind.org/techref/io/stepper/hipwrbp-gm.htm "Design of a High Current Bipolar Stepper Motor Driver"]
* [http://roko.ca/articles/hbridge.php H-Bridge Fundamentals] An in-depth article on the design of Mosfet H-Bridges
* [http://PMinMO.com PMinMO.com] Open Source circuits and information on stepper motor controllers]
* [http://www.epanorama.net/links/motorcontrol.html ePanorama] ePanorama Motor Control page
* [http://www.isl.ee.boun.edu.tr/projects/motordriver/ "Electronic Design of DC Motor Drives"] has detailed schematics and PCB layout for a system that has a PC send commands through the serial port to a Microchip PICmicro, which does PWM control of 2 H bridges. Each half-bridge uses a IRF9530N (100V 14A pfet plus flyback diode) and a IRF530 (IRF530NPBF: 100V 17A nfet plus flyback diode), driven by a small transistor inverter based on a BD135 npn, for a total of 12 discrete transistors.
* [http://openservo.com/ OpenServo wiki] -- developing a digital servo motor that accepts "Go to position X" commands and also more complex curves, and returns actual servo position, speed, voltage and power consumption.
* [http://homepages.which.net/~paul.hills/SpeedControl/Mosfets.html MOSFETs and MOSFET drivers]
* L297 stepper motor controller + L298 dual full-bridge driver: for driving one (4-wire) bipolar stepper motor (2 A); direction and step inputs; half-stepping; on-chip PWM chopper limits current. external diodes are required (preferably Shottky). (Both chips come in through-hole and SMT versions)
* L298 dual full-bridge driver can also be used to drive 2 independent DC motors (2 A each); external diodes are required (preferably Shottky). L293D is similar, but only rated up to 1 A, 36 V.
* [http://www.sparkfun.com/commerce/product_info.php?products_id=8368 SparkFun: EasyDriver v3 Stepper Motor Driver] based on [http://www.sparkfun.com/datasheets/Robotics/A3967.pdf A3967 microstepping driver] chip; up to 750mA, 30 V.
* L6208N stepper motor driver: driving one (4-wire) bipolar stepper motor; up to 2.8 A, 52 V. direction and step inputs. PWM current control; includes internal diodes. over-current and thermal protection. half-stepping. MC3479 stepper motor drive is similar, but only rated up to 350 mA, 16 V.
* [http://www.nanotec.de/page_product__smc11__en.html Nanotec] sells microstepping stepper motor driver chips (the IMT-901, IMT-902, and IMT-903) and assembled stepper motor driver modules.
* [http://forums.reprap.org/read.php?13,5128 Reprap: Arduino] has a long side-thread on various motor driver chips.
* lots of [http://octopart.com/search?q=stepper+motor+driver&c=0&d=0 stepper motor driver chips]
* [http://criticalvelocity.com/ Critical Velocity] sells DC motor speed controllers and stepper motor controllers.
* [http://geckodrive.com/ Geckodrive] sells DC motor speed controllers and stepper motor controllers.

[[astronomy]] telescopes use motor drivers:
* [http://u.webring.com/hub?ring=scopedrive scope drive webring]: a selection of Websites that display procedures to equip amateur telescopes with homemade computerized drive systems
* [http://locl.net/homes/scopedrive/ "scopedrive" for automating telescopes]

Robots use motor drivers.
* [http://glendale.edu/robotics_club/ Glendale robotics club] (Glendale CA)
* [http://www.robotroom.com/HBridge.html "H bridges" by David Cook at the ROBOT ROOM(TM)]
* [http://mcmanis.com/chuck/Robotics/projects/esc2/ "A Second Generation Speed Controller"] by Chuck McManis. Can handle 200 amps continuously. Uses two PIC16F628 chips driving sixteen IRF1010E FETs: "(I like to call it a "two way SMP microkernel with serial cluster interconnect" as that sounds better than "a couple of PICs with their serial ports wired together" :-)"

[[Category:Projects]]

WikiNode

2007-12-01T18:36:13Z

158.39.243.114: Seriously. Restrict editing access for non-registered users, get some moderators, and write-protect main page and possibly some others.

Welcome to Open Circuits.
Open Circuits is a wiki for sharing electronics knowledge, schematics, board layouts, and parts libraries.

== key points of interest ==

* [[Main Page]]
* [[Open_Circuits:Community_Portal]]
* [[Projects]]
** open hardware cell phone projects: [[Open Mobile Gadgets]], [[Cellular Rotary Phone]]
* [[Components]]
* [[Techniques]]

== wiki-nodes of neighboring wiki ==

open hardware cell phone wiki:

* [http://opencellphone.org/ TuxPhone wiki at http://opencellphone.org/]
* [http://hbmobile.org/wiki/ Homebrew Mobile Phone Club wiki at http://hbmobile.org/wiki/]
* [http://widgetry.org/dokuwiki/ OpenCell wiki at http://widgetry.org/dokuwiki/]
* [http://wiki.openmoko.org/ OpenMoko wiki at http://wiki.openmoko.org/] discusses open hardware cell phone you can buy now.
* [http://iphone.fiveforty.net/wiki/ wiki for open-source software for a popular (but proprietary hardware) phone]

other open wireless communications wiki:

* [http://wsn.oversigma.com/ WSN, the Wireless Sensor Network wiki] discusses wireless sensor networks. (wired sensor network discussion is also tolerated :-).
* [http://wiki.twibright.com/ a wiki for RONJA] (Reasonable Optical Near Joint Access) Free Space Optics device[http://en.wikipedia.org/wiki/RONJA]. ("free technology" is the same as "open hardware", right?)
* [http://wiki.openwrt.org/ OpenWRT wiki]: "OpenWrt is an open source project to create a free embedded operating system for network devices."

other related wiki:

:For open source software (or open source in general) visit the [http://opensource.wikia.com/wiki/Main_Page Open Source Wikia].

* [http://adciv.org/ the advanced civilization wiki] discusses "Open collaborative design", which seems to include the sort of [[open hardware]] designs we share at Open Circuits.
* [http://openservo.com/ OpenServo wiki] -- developing a digital servo motor that accepts "Go to position X" commands and also more complex curves, and returns actual servo position, speed, voltage and power consumption.
* [http://electronicschat.org/ the Electronics Chat wiki]
* [http://hcvl.hci.iastate.edu/cgi-bin/openEyeswiki/index.cgi the openEyes wiki] discusses an open-source open-hardware toolkit for low-cost real-time eye tracking.
* [http://wiki.asiaquake.org/openeeg/published/WikiNode the OpenEEG wiki] discusses building an OpenEEG, safe ways to attach it to your head, and software for it.
* [http://communitywiki.org/odd/ComputerComponent/WikiNode Computer Component wiki] "for computer and electronics enthusiasts to learn and contribute to an online database of computer hardware and electronics with an emphasis on how-to guides."

* [http://nslu2-linux.org/ the NSLU2-Linux development group] seems to do a lot of wiring and soldering. ''needs wiki-node''
* [http://wikidevices.org/ Wiki Devices] "a highly organized repository for objective information, as well as opinions on consumer electronics."
* [http://wikiindex.com/Build_Your_Own_Arcade the Build Your Own Arcade controls wiki]
* [http://www-robotics.usc.edu/~dshell/roboticswiki/ Robotics wiki] ''(offline as of 2007-07-07)''
* [http://geda.seul.org/wiki/ the gEDA wiki] discusses "the gEDA project" -- developing a full GPL‘d suite of Electronic Design Automation tools (electrical circuit design, schematic capture, simulation, prototyping, and printed circuit board (PCB) layout.
* microcontroller wiki:
** [http://gainer.cc/wiki/ the Gainer wiki] discusses the Cypress PSoC microcontroller
** [http://avrwiki.com/ the Atmel AVR wiki] discusses the Atmel AVR series of microcontrollers (see also the Arduino wiki)
** [http://techref.massmind.org/techref/piclist/ the PICList at the massmind] and [http://oase.uci.kun.nl/~mientki/wikifarm/stef/index.php PiciWiki] discusses the Microchip PIC series of microcontrollers
** [http://www.open-research.org.uk/ARMuC/ the ARM microcontroller wiki]
** [http://gnusim8085.sourceforge.net/ the GNUSim8085 wiki] for the Intel 8085 microprocessor
** [http://nioswiki.jot.com/ Nios community wiki] discusses the Nios II processor, and how to implement it on a FPGA
** [http://jopdesign.com/wiki/index.php the JOP wiki discusses the Java Optimized Processor, a simple and small Java processor optimized to execute Java bytecode, implemented in a low cost FPGA]
** [http://wiki.opensparc.net/ the OpenSPARC Wiki] discussing open-source versions of the SPARC processor architecture, including implementing it in a FPGA
* [http://en.wikibooks.org/wiki/Embedded_Systems the Embedded Systems wikibook]
* [http://sensorwiki.org/ the sensor wiki]
* [http://linuxtv.org/wiki/ the LinuxTV wiki] occasionally has some chip-level information, such as the [http://linuxtv.org/wiki/index.php/I2c_Protocol I2C protocol] and [http://linuxtv.org/wiki/index.php/BT878 sampling analog data at 16 bits and 448000 Samples per second with a BT878 chip]
* [http://howto.wikia.com/wiki/WikiNode WikiHowto] occasionally has electronic projects such as [http://howto.wikia.com/wiki/Howto_build_an_ultra_low_power_clock_with_a_large_period WikiHowto: Howto build an ultra low power clock with a large period]
* [http://wiki.duskglow.com/ The Open Graphics Project (OGP) is developing graphics cards with fully published specs and open source drivers.] Since the first version will be a FPGA, is also collecting information on FPGA programming and interfacing.
* [http://elinux.org/ the embedded Linux wiki] has information on running Linux on several small ARM-based embedded systems. Also TexasInstruments OMAP processors.
* [http://wikihost.org/wikis/openhardware/ the Open Hardware wiki] has electronics projects of various levels of complexity; the most complicated appears to be "KAD", a FPGA on a PCI card designed for reconfigurable computing.
* [http://pminmo.com/PMinMOwiki/index.php5 the PMinMO.com wiki] describes an open-source CNC machine -- software, electronics, motors, hardware, etc. -- and related information, such as [http://pminmo.com/PMinMOwiki/index.php5?title=CNC_PCB_Milling CNC PCB milling]. (was: [http://pminmo.com/wiki/] ) ''needs WikiNode''
* [http://linuxrobots.org/wiki/WikiNode Linux Robots] -- robots that run Linux
* [http://protel-users.org/ Protel users wiki], for people who design and draw schematics and circuit boards with Protel.
* [http://elinux.org/wiki/ embedded Linux wiki] ''needs wikinode''
* [http://vems.hu/wiki/ VEMS wiki] has some interesting electronics projects. In particular, the [http://www.vems.hu/wiki/index.php?page=GoBox GoBox project] to tune automobile engines to minimize the amount of fuel used. ''needs wikinode''
* various small CPU modules that have their own wiki (see also [[ARMUS Embedded Linux Board]] )
** [http://balloonboard.org/balloonwiki/WikiNode Balloonboard Wiki] for the Balloon Project. They have developed a small single-board computer that can run Linux. Also discusses "The Balloon Open Hardware License (BOHL) ... The license is intended as a general purpose open hardware license".
** [http://docwiki.gumstix.org/ gumstix wiki] : "[http://docwiki.gumstix.org/Schematics Schematics and layouts for all gumstix expansion boards] are available under a Creative Commons license." ''needs wikinode''
** [http://virtualcogs.com/wiki/ Virtual Cogs wiki] describes a CPU board that uses a stacking connector system.
** [http://wiki.emqbit.com/free-ecb-at91 the emQbit wiki] discusses "The Free ECB_AT91 V1 is a Single Board Computer made by emQbit. You can download the specs and build your own." based on a 180 MHz ARM9 processor (Atmel AT91RM9200); runs Linux.
** [http://arduino.cc/playground/ Arduino playground] discusses the Arduino board based on the Atmel AVR ATmega168. (See also the Atmel AVR wiki).
* [http://openjtag.net/ the OpenJTAG wiki] ( http://openjtag.net/ )
* [http://reprap.org/bin/view/Main/WebHome the RepRap wiki] discusses the RepRap project to build a "Replicating Rapid-prototyper", a self-copying 3D printer. "Complete open-source instructions and plans are published on this website for zero cost and available to everyone so, if you want to make one yourself, you can."
* [http://analogwiki.com/ the Analog wiki] "The Wiki for Design & Verification Engineers by Design & Verification Engineers."
* [http://editthis.info/JMRI JMRI wiki ( http://editthis.info/JMRI )] The JMRI project is building tools for model railroad computer control.
* [http://dccwiki.com/ the DCC wiki ( http://dccwiki.com/ )] ("Digital Command Control") discusses computer-controlled model railroads.
* [http://hardwarebook.info/ the Hardware Book. Internet's largest free collection of connector pinouts and cable descriptions.] ''needs WikiNode''
* [https://isl.ncsa.uiuc.edu/twiki/bin/view/OpenFPGA the OpenFPGA wiki] ''needs WikiNode''
* [https://devel.goto10.org/packets/wiki/CATkit the CATkit wiki: CATkit is an open hardware project] designed as a standalone interactive Forth computer for audio sound artists. (Based on Microchip PIC 18F).
* [http://openbios.org/ the OpenBIOS project wiki] discusses several free and open source implementations of IEEE 1275-1994 (also called "Open Firmware"). Open Firmware allows expansion cards to provide a "boot ROM" that works all common platforms, like x86, AMD64, PowerPC, ARM and Mips.
* [http://obook.info/ the OpenBook wiki] discusses OpenBook, an open source hardware and software project designing a computer tablet ... Everyone can contribute and help to shape the OpenBook hardware and software specifications.
* [https://events.ccc.de/camp/2007/ Chaos Communication Camp wiki]
* [http://tubeopedia.com/ Tubeopedia.com] discusses vacuum tube technology and science, circuits, theory, people and equipment related to vacuum tubes.
* [http://opencircuitdesign.com/cgi-bin/wiki.pl OpenCircuitDesign.com , the other Open Circuit Wiki] discusses mostly free tools for designing integrated circuits.

----

Please add closely-related wiki. Keep the 7 or so of the most-closely-related wiki.
Move less-relevant wiki to WikiIndex.

''Are any of the wiki listed at http://www.communitywiki.org/odd/SoftwareBazaar/MicrocontrollerProgramming relevant enough to list here?''

Main Page

2007-12-01T18:31:12Z

158.39.243.114: Fixed spam. Might we get a fix for privileges?

Open Circuits is a wiki for sharing [[open source electronics]] knowledge, schematics, board layouts, ports and parts libraries. This include open hardware [[Music Player]]s, [[atomic microscope]]s, [[PC]], [[PDA]] and [[Open Mobile Gadgets|mobile phone]]s, and [[battery|batteries]]. Please help us to build this resource by submitting your component descriptions, projects, techniques, and PCB footprints.

== [[Projects]] ==
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== [[Components]] ==
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== [[Techniques]] ==
How to do things.

== [[PCB Footprints]] ==
Don't reinvent the wheel. Known working open PCB footprints for various components.

== help us make Open Circuits better ==

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