Changes between Initial Version and Version 1 of BioSensorProto2Implementation

Timestamp:

Nov 8, 2013, 10:17:54 AM (10 years ago)

Author:

Eric Hazen

Comment:

--

BioSensorProto2Implementation

@@ +1 @@
+Back to main [[BioCompoundSensor]]
+
+This page provides implementation details for Prototype II for the designers.
+
+A sine wave with 16-bit precision will be pre-loaded in a 512-word block RAM on the FPGA.
+A programmable ''''phase increment''' register controls the stimulus frequency.
+At the maximum 100Hz frequency, the waveform DAC will be updated from the RAM
+at 51.2kHz.  An ADC will measure the current from the reference and active devices
+alternately at 51.2kHz, providing a new measurement of each at 25.6kHz.
+This will be accomplished by operating the AD7682 ADC in a mode where it takes
+samples alternately on two inputs.
+
+As each sample is acquired, it will be multiplied by both the in-phase (sin)
+and quadrature (cos) values retrieved from the RAM, and the results added to a 24-bit
+accumulator.  Four accumulators are required (reference sin, reference cos, active sin,
+active cos).  Once per stimulus cycle (maximum 100Hz) the four accumulators are zeroed
+and the four 32-bit values transferred to the microcontroller.
+
+In addition, the raw samples are stored in an additional block ram which may be read
+by the microcontroller for diagnostic purposes.
+
+= PCB Documentation =
+* [http://ohm.bu.edu/~pbohn/Bio_Compound_Sensor/Documentation/ Design Documentation]
+* [http://ohm.bu.edu/~pbohn/Bio_Compound_Sensor/Design_Files/Gerber/ Gerber Files]
+* Schematic: [http://ohm.bu.edu/~hazen/BioSensor/Proto2/bill_sch.pdf bill_sch.pdf]
+• [http://ohm.bu.edu/~hazen/BioSensor/Proto2/schematic.txt Notes] • [[SchematicRevisions]]
+
+= Firmware =
+
+== Documentation ==
+
+* Interface Protocol Specification: [http://ohm.bu.edu/~hazen/BioSensor/Proto2/PicoBlazeRequirements_App_6Feb.pdf PicoBlazeRequirements_App_6Feb.pdf]
+* List of signals: [http://ohm.bu.edu/~hazen/BioSensor/FPGA_signals.txt FPGA_signals.txt]
+* BioSensor How to Guide: [http://ohm.bu.edu/~pbohn/Bio_Compound_Sensor/Documentation/bio_howto_2009-04-01.pdf bio_howto_2009-04-01.pdf]
+* List of registers: [http://ohm.bu.edu/~pbohn/Bio_Compound_Sensor/Documentation/bio_regs_Apr08.pdf bio_regs_Apr08.pdf]
+
+== Source Code ==
+
+=== Working Code ===
+
+* [http://ohm.bu.edu/~hazen/BioSensor/SourceCode/PicoBlaze_2009-05-01.zip PicoBlaze_2009-05-01.zip]
+Working version with one significant known bug in "AC" command (repeats measurements)
+
+=== Test Versions ===
+
+* ** [http://ohm.bu.edu/~pbohn/Bio_Compound_Sensor/Design_Files/backup_xilinix/ BioSensor Firmware]
+* Firmware for testing the PicoBlaze software
+* BioSensor_pcbv1 [http://ohm.bu.edu/~hazen/BioSensor/SourceCode/BioSensor_pcbv1.psm .psm] [http://ohm.bu.edu/~hazen/BioSensor/SourceCode/BioSensor_pcbv1.vhd .vhd]
+* [http://ohm.bu.edu/~hazen/BioSensor/SourceCode/SoftwareTest_2009-03-11.tar.gz SoftwareTest_2009-03-11.tar.gz]
+* [http://ohm.bu.edu/~hazen/BioSensor/SourceCode/SoftwareTest_2009-02-11.zip SoftwareTest_2009-02-11.zip]
+* [http://ohm.bu.edu/~hazen/BioSensor/SourceCode/SoftwareTest_2009-02-11.tar.gz SoftwareTest_2009-02-11.tar.gz]
+
+The FPGA logic (designed by Bill) will provide the following:
+
+* Interface to 4-output DC bias DAC
+* Interface to 2-output offset cancel DAC (may be combined with above)
+* Waveform BRAM to hold 256-sample 16-bit sinusoidal waveform
+* Logic to drive an AC DAC from above at a programmable rate (1-100Hz waveform rate,
+  256Hz-25.6kHz sample rate)
+* Logic to read out at the same sample rate one multiplexed ADC reading
+  the AC current waveform(s) measured on the samples.  The ADC will provide
+  one or two 16-bit samples (reference and active separately, or the difference).
+  The ADC outputs will go to two destinations:
+ * 1. Multiply/accumulate logic which will multiply the samples by the sin and cos
+  outputs from the waveform generator and accumulate a 24-bit sum.  There will
+  be a total of 4 such sums (Active sin, active cos, reference sin, reference cos)
+  produced once per cycle and made available to the PicoBlaze
+ * 2. A block ram which can hold one complete waveform (256 samples) of 2x16 bits each.
+* A control register with bits for gain select, multiplexer settings and mode selects
+* A status register of some sort
+
+The PicoBlaze interface will be bus-oriented, as described here: [[BioDelayGenerator]]
+except that the address will be expanded to 7 bits.
+
+= PCB Components =
+
+* [http://focus.ti.com/lit/ds/symlink/dac7564.pdf DAC7564]
+* [http://focus.ti.com/lit/ds/symlink/dac7551.pdf DAC7551]
+* [http://focus.ti.com/lit/ds/symlink/tlv5638.pdf TLV5638]
+* [http://ohm.bu.edu/~hazen/DataSheets/AD/AD7682_7689.pdf AD7682]
+* 8 current-sensitive amplifiers with switchable 10x gain (wired to 4 inputs each on the ADCs)
+* 8 100x gain voltage amplifiers with offset cancel input from DAC
+* A Spartan-3AN FPGA (probably an XC3S50AN-TQ144).
+* An RS-232 interface
+* A crystal oscillator (50MHz?)
+* Voltage regulators to power everything from +4.5, -4.5V from batteries or external power
+* LEDs / buttons
+* Connectors:
+ * Carrier PCB (two 12-pin headers)
+ * DB-9 for RS-232
+ * 2mm round coax jack (or similar) for external power
+ * 4-pin Molex for battery power
+ * Auxiliary connector (for i.e. LCD character display)
+
+= LCD Display =
+
+An LCD display may be added.  We have a Digilent PMOD-CLP [http://www.digilentinc.com/Data/Products/PMOD-CLP/PmodCLP_rm_RevA.pdf (data sheet)].  This uses the KS0066 controller from Samsung [http://ohm.bu.edu/~hazen/DataSheets/Samsung/KS0066_datasheet.pdf (data sheet)]
+operating in 4-bit mode is available
+[http://www.aut.bme.hu/VillamosSzakiranyBSc/files/EUKs0066.pdf here]
+
+