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* This can be used for a brain-computer interface with biofeedback using a flex sensor or servo to detect fingure movements. | * This can be used for a brain-computer interface with biofeedback using a flex sensor or servo to detect fingure movements. | ||
* The [http://opencircuits.com/LT1168 LT1168 Programmable-Gain Precision Instrumentation Amplifier] is used to amplify the weak electric signals coming from the brain through electrodes attached to the scalp, and has internal protection circuitry for the user. | * The [http://opencircuits.com/LT1168 LT1168 Programmable-Gain Precision Instrumentation Amplifier] is used to amplify the weak electric signals coming from the brain through electrodes attached to the scalp, and has internal protection circuitry for the user. | ||
+ | * Several matched [http://opencircuits.com/LT1114 LT1114 Low Power Precision OP-Amps] are used for amplification and filtering of the signals. | ||
* ESD Protection in [http://opencircuits.com/LT1168 LT1168 Programmable-Gain Precision Instrumentation Amplifier] Chips have been chosen that fallow the human body model of esd protection this can be seen in the 1168 datasheet. | * ESD Protection in [http://opencircuits.com/LT1168 LT1168 Programmable-Gain Precision Instrumentation Amplifier] Chips have been chosen that fallow the human body model of esd protection this can be seen in the 1168 datasheet. | ||
* To reduce noise in the readout of the analog part of this circuit, a common-mode feedback is passed back into the body by the driver right leg circuit, for example, 60Hz noise from nearby A/C power wiring. | * To reduce noise in the readout of the analog part of this circuit, a common-mode feedback is passed back into the body by the driver right leg circuit, for example, 60Hz noise from nearby A/C power wiring. | ||
− | * The | + | * The analog signal prossesing board will digitize the signal and pass the data to the control board. The control board is based on the AVR Mega168 which will, further process the signals, and provide an interface to a computer. |
− | *we are using the AVR Mega 168. | + | *we are using the AVR Mega 168 or Mega8. |
− | * | + | *AVR C and the AVR Mega 168 allows for a complete open source system... |
== News == | == News == | ||
− | The | + | The design is switching from LT switcher CAD (aka [http://www.nuhorizons.com/xpresstrack/ltcswitcher/ LTspice SwitcherCAD]) to EAGLE CAD, because the auto-router is excellent for open-source productivity. It will allow the design to evolve faster and with less work with a wider selection of [[PCB Manufacturers]]. |
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− | It will allow the design to evolve faster and with less work with a wider selection of [[PCB Manufacturers]] | ||
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The robot arm interface by [http://www.answers.com/topic/miguel-nicolelis Miguel Nicolelis]is very inspiring. He used implanted electrodes to monitor and allow monkeys to control a robot arm as if it was their own. Could the PCEEG do the same with its electrodes on the scalp. Only the future will show. | The robot arm interface by [http://www.answers.com/topic/miguel-nicolelis Miguel Nicolelis]is very inspiring. He used implanted electrodes to monitor and allow monkeys to control a robot arm as if it was their own. Could the PCEEG do the same with its electrodes on the scalp. Only the future will show. | ||
== Status == | == Status == | ||
− | * | + | *Editing the code of the Open EEG and Monolith EEG to be more portable and utilize avr-libc libraries more. |
*Using the open Boarduno design to prototype the design. | *Using the open Boarduno design to prototype the design. | ||
== Hardware Overview == | == Hardware Overview == | ||
− | + | Here is a diagram of how the analog signal processing boards and the microprocessor board will come together. | |
+ | [[Image:Pceeg.jpg]] | ||
+ | Here is how the analog signal prossesing board will come together. | ||
+ | [[Image:newpceeghddesign.png]] | ||
== Description of How it Works == | == Description of How it Works == | ||
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Insulated wires attached to the electrodes bring the signals to the signal processing daughter board. | Insulated wires attached to the electrodes bring the signals to the signal processing daughter board. | ||
− | The signal | + | The signal processing daughter board is responsible for filtering and digitizing the signals from the body. |
− | Then the signals are passed to the | + | Then the signals are passed to the control board that is the motherboard. |
The motherboard then can pass the signal to a larger computer. | The motherboard then can pass the signal to a larger computer. | ||
− | On the | + | On the signal processing daughter board is an anti-aliasing filter, an amplifier, and a [[Integrated_Circuits#ADC_analog_to_digital_converter | analog to digital converter]]. |
The instrumentation amplifier amplifies the differential analog signal on the input wires. | The instrumentation amplifier amplifies the differential analog signal on the input wires. | ||
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Then the signal is digitized by a a/d converter. | Then the signal is digitized by a a/d converter. | ||
The a/d converter has approximately 20 bits accuracy so the signal does not have to be conditioned or filtered as much. | The a/d converter has approximately 20 bits accuracy so the signal does not have to be conditioned or filtered as much. | ||
− | The "right leg driver" circuit on the | + | The "right leg driver" circuit on the daughter board is intended to decrease common mode signal. |
That circuit inverts the common mode signal from the instrumentation amp, sums the result from each instrumentation amp, and sends the total back to the body. | That circuit inverts the common mode signal from the instrumentation amp, sums the result from each instrumentation amp, and sends the total back to the body. | ||
− | The ADCs | + | The ADCs simultaneously digitize all the analog signals ''(really?)''. |
The ADCs send bits of information (representing the original analog electrical signals) to the controller motherboard. | The ADCs send bits of information (representing the original analog electrical signals) to the controller motherboard. | ||
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The controller board can be programmed using AVR GCC. | The controller board can be programmed using AVR GCC. | ||
− | + | [[image:UCschematicardunonmonolith.png]] | |
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− | + | Working on some other improvements... C123 with 1uF is much too small. Use 1000uF or so instead. | |
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− | + | [[image:adschematicad1256devbrdnmonolith.png]] | |
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== Parts used in the PCEEG: == | == Parts used in the PCEEG: == | ||
* [http://opencircuits.com/LT1168 LT1168 Resistor-Programmable-Gain Precision Instrumentation Amplifier] is used to amplify the weak electric signals coming from the brain through electrodes attached to the scalp, etc. | * [http://opencircuits.com/LT1168 LT1168 Resistor-Programmable-Gain Precision Instrumentation Amplifier] is used to amplify the weak electric signals coming from the brain through electrodes attached to the scalp, etc. | ||
− | * and | + | * Several [http://opencircuits.com/LT1114 LT1114 Low Power Precision OP-Amps] are used for amplification and filtering of the signal |
==ESD Protection in 1168== | ==ESD Protection in 1168== | ||
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* Maxima a computer algebra system s used for graphing and math displays. | * Maxima a computer algebra system s used for graphing and math displays. | ||
*SPI interface code for a/d converters from TI for developers | *SPI interface code for a/d converters from TI for developers | ||
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=== How You Can Help === | === How You Can Help === | ||
#. get the tools | #. get the tools | ||
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== Open Source Circuit Design == | == Open Source Circuit Design == | ||
* [http://opencircuits.com/Programmable_Chip_EEG Open Source Circuit Design ] | * [http://opencircuits.com/Programmable_Chip_EEG Open Source Circuit Design ] | ||
− | * [http:// | + | * [http://pceegbci.blog.com/ The Programmable Chip EEG Open Source Circuit Design BLog] ''(BrokenLink -- I hope this is only temporarily offline. --[[User:DavidCary|DavidCary]] 10:12, 8 October 2007 (PDT) )'' |
== ideas for future work == | == ideas for future work == | ||
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Please contribute and make the PCEEG a great tool for researching brain computer interfaces. | Please contribute and make the PCEEG a great tool for researching brain computer interfaces. | ||
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== See also: == | == See also: == | ||
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* [https://electrical.codidact.com/posts/288010 "What is a good PCB-layout? ... an ECG-amplifier circuit."] | * [https://electrical.codidact.com/posts/288010 "What is a good PCB-layout? ... an ECG-amplifier circuit."] | ||
* [http://www.nytimes.com/2008/01/15/science/15robo.html?ex=1359090000&en=69146e0fb3807a74&ei=5124&partner=permalink&exprod=permalink/ Monkey’s Thoughts Propel Robot, a Step That May Help Humans ] | * [http://www.nytimes.com/2008/01/15/science/15robo.html?ex=1359090000&en=69146e0fb3807a74&ei=5124&partner=permalink&exprod=permalink/ Monkey’s Thoughts Propel Robot, a Step That May Help Humans ] | ||
+ | * [http://wiki.asiaquake.org/openeeg/published/ The OpenEEG wiki] | ||
+ | * [http://pceegbci.blog.com/ The Open EEG Brain Computer Interface BLog] | ||
* [http://www.larryheadinstitute.com/eeg-training.html EEG Training Seminars] | * [http://www.larryheadinstitute.com/eeg-training.html EEG Training Seminars] | ||
+ | * [http://pceeg.wikia.com/wiki/Main_Page wiki cities on pceeg] | ||
* [http://pceeg.sourceforge.net pceeg.sourceforge.net] | * [http://pceeg.sourceforge.net pceeg.sourceforge.net] | ||
* [http://www.answers.com/topic/miguel-nicolelis miguel nicolelis] | * [http://www.answers.com/topic/miguel-nicolelis miguel nicolelis] | ||
* [http://maxima.sourceforge.net/ Maxima - a computer algebra system] | * [http://maxima.sourceforge.net/ Maxima - a computer algebra system] | ||
− | * [[PCB Manufacturers]] | + | * [http://www.scienceprog.com/ digital high pass filters and other circuits] |
− | + | * [http://hcvl.hci.iastate.edu/cgi-bin/openEyes.cgi human and computer vision lab] | |
+ | * [[PCB Manufacturers]] such as [http://www.batchpcb.com/index.php www.batchpcb.com] | ||
* [http://vulliard.dyndns.org/~vulliard/ eeg biofeedback "mind machine"] | * [http://vulliard.dyndns.org/~vulliard/ eeg biofeedback "mind machine"] | ||
* [http://freenet-homepage.de/moosec/projekte/simpleeeg/index-Dateien/Page431.htm monolith eeg] | * [http://freenet-homepage.de/moosec/projekte/simpleeeg/index-Dateien/Page431.htm monolith eeg] | ||
+ | * [http://mindhacks.com/blog/2007/01/meg_scanning_the_bra.html yet another pundit disrespects the EEG] | ||
+ | * [http://www.pololu.com/laser_cutting.html lazer cutting for box & solder paste stencil] | ||
+ | * [http://www.amazon.com/Build-Your-Printed-Circuit-Board/dp/007142783X?tag2=zottmann1-20 Build Your Own Printed Circuit Board] | ||
* [http://www.stencilsunlimited.com/solder_products.php solder paste for surface mount that can be stored at room temperature] | * [http://www.stencilsunlimited.com/solder_products.php solder paste for surface mount that can be stored at room temperature] | ||
* The thread [http://forum.microchip.com/tm.aspx?m=114626 "amplifying biomedical signals: 150 uA with 16 bit resolution?"] has several op-amp suggestions, and mentions that "a good, low-noise, low-cost, isolated EMG/EEG amplifier is one of the most demanding analog electronics designs." | * The thread [http://forum.microchip.com/tm.aspx?m=114626 "amplifying biomedical signals: 150 uA with 16 bit resolution?"] has several op-amp suggestions, and mentions that "a good, low-noise, low-cost, isolated EMG/EEG amplifier is one of the most demanding analog electronics designs." | ||
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* Is there a [http://www.electronicproducts.com/ShowPage1.asp?SECTION=&PRIMID=&FileName=medtelconf3%2Ejul2004%2Ehtml&ReturnLink=%2FSearch1%2Easp%3FManufacturer%3D%26Keyword%3Dimplantables%26Slot%3D0%26StartNum%3D1%26stype%3D%26year%3D10&MonthYear=Jul+2004 Medical Electronics Forum]? | * Is there a [http://www.electronicproducts.com/ShowPage1.asp?SECTION=&PRIMID=&FileName=medtelconf3%2Ejul2004%2Ehtml&ReturnLink=%2FSearch1%2Easp%3FManufacturer%3D%26Keyword%3Dimplantables%26Slot%3D0%26StartNum%3D1%26stype%3D%26year%3D10&MonthYear=Jul+2004 Medical Electronics Forum]? | ||
* [http://www.makezine.com/blog/archive/2006/01/homemade_electrocardiograph.html Make: Homemade Electrocardiograph] ([http://www.eng.utah.edu/~jnguyen/ecg/ecg_index.html] recommends skin lotion or shampoo as a low-cost electrode gel) | * [http://www.makezine.com/blog/archive/2006/01/homemade_electrocardiograph.html Make: Homemade Electrocardiograph] ([http://www.eng.utah.edu/~jnguyen/ecg/ecg_index.html] recommends skin lotion or shampoo as a low-cost electrode gel) | ||
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[[Category:Projects]] | [[Category:Projects]] |