EEVblog Electronics Community Forum
Electronics => Beginners => Topic started by: amangg on April 20, 2017, 12:12:02 pm
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Hey everyone,
I have been working on a project on quantifying the changes in the properties of fruits/vegetables to measure the shelf life. I had recently bought an ethylene gas sensor from china but am facing certain issues with it (being new to the field sensors and board designs). The sensor is as follows :-
http://www.winsen-sensor.com/products/4-series-electrochemical-toxic-gas-sensor/me3-c2h4.html (http://www.winsen-sensor.com/products/4-series-electrochemical-toxic-gas-sensor/me3-c2h4.html)
As per the datasheet, the concentration of ethylene is reflected by changes in the current produced so to measure the current produced I am using ACS712 chip on the board and the output shall be routed to ADC chip which will be connected to the raspberry pi (along with other sensors).
I am finding trouble with the ACS712 chip as it has rounded input :-
(http://embedded-lab.com/blog/wp-content/uploads/2012/01/PinDiagrams.jpg)
Could you help me out with the working of the ACS712 chip ? If I have a single output from the ethylene sensor that how to connect it to the ACS712 ?
thanks in advance.
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Since your ethylene chip is single ended output ground the
IP- pins and feed your output to the IP+ pins. Note the sens-
itivity of the 712 is 66 - 185 mV/A. So what is the current
range out of the ethylene sensor ?
Also note the absolute accuracy of the 712 OK, but if
you need more absolute accuracy you would mux a known current
reference into the 712 so that you could remove offset and G
error in the 712. A PSOC would be a good possibility for this.
See next post.
Regards, Dana.
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Example use of PSOC onchip reference and current source -
(https://images.duckduckgo.com/iu/?u=http%3A%2F%2Fwww.eevblog.com%2Fforum%2Fmicrocontrollers%2Fpsoc-examples%2F%3Faction%3Ddlattach%3Battach%3D108202&f=1)
Mux example - https://duckduckgo.com/?q=psco+creator+images+current&atb=v58-5_a&iar=images&iax=1&ia=images&iai=http%3A%2F%2Fwww.cypress.com%2Fsites%2Fdefault%2Ffiles%2Finline%2FfckImages%2Fmyresources%2FKBA85474.jpg (https://duckduckgo.com/?q=psco+creator+images+current&atb=v58-5_a&iar=images&iax=1&ia=images&iai=http%3A%2F%2Fwww.cypress.com%2Fsites%2Fdefault%2Ffiles%2Finline%2FfckImages%2Fmyresources%2FKBA85474.jpg)
For me what stands out is -
1) Routability
2) Fast 12 bit SAR A/D and slow 20 bit DelSig
3) DFB (Digital Filter Block) that is dual channel, handle FIR or IIR filters, or DFB
can be used as a GP fast processor block, similar to RISC block
4) MSI logic elements GUI based and/or the UDB Verilog capability. Eg. the FPGA
like capability
5) Onboard Vref
6) IDAC, VDAC, OpAmps (up to 4), comparator, mixer, switch cap, analog mux....
7) LCD, COM, UART, I2C, I2S, One Wire, SPI, Parallel, LIN, CAN, BLE, USB
9) Custom components capability, create with schematic capture or Verilog
10) DMA to offload processes like filters, COM, Display
11) ARM M0 (PSOC 4) or M3 (PSOC 5LP) or 8051 core(PSOC 3)
12) Extensive clock generation capabilities
13) All components supported by extensive prewritten APIs
https://www.element14.com/community/thread/23736/l/100-projects-in-100-days?displayFullThread=true (https://www.element14.com/community/thread/23736/l/100-projects-in-100-days?displayFullThread=true)
http://www.cypress.com/documentation/code-examples/psoc-345-code-examples (http://www.cypress.com/documentation/code-examples/psoc-345-code-examples)
Great video library
Attached component list. A component is an on chip HW resource.
Free GUI design tool with schematic capture, "Creator". Components have rich API library attached
to each component. Compilers free as well.
PSOC 4 is low end of family, consider 5LP parts as well. PSOC 4 also has arduino footprint boards (pioneer) as well
https://www.elektormagazine.com/labs/robot-build-with-cypress-psoc (https://www.elektormagazine.com/labs/robot-build-with-cypress-psoc)
http://www.cypress.com/products/32-bit-arm-cortex-m-psoc (http://www.cypress.com/products/32-bit-arm-cortex-m-psoc)
Regards, Dana.