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15. Re: ADC problem
userc_38487 Nov 24, 2012 9:27 AM (in response to userc_42486)1 of 1 people found this helpfulHave you tried with ADC Continuous mode of operation ?
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16. Re: ADC problem
helic_263931 Nov 24, 2012 3:30 PM (in response to userc_42486)1 of 1 people found this helpfulI think the TextLCD is not asynchronous. All write commands wait until the LCD is ready. This means that it will slow down the loop to accomodate the LCD speed. But writing so fast means you cannot really ready anything on it...
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17. Re: ADC problem
DaKn_263916 Nov 24, 2012 4:10 PM (in response to userc_42486)1 of 1 people found this helpfulI should have been more explicit on what is asynch and what is not.
The 44780 Controller has a busy flag which is the basis of handshake for writes/reads of commands or data. Hence that is a synch interface.
What is asynch is the relationship of what is written and when it gets to actual LCD segments, due to an internal controller that is not synced to MPU clock in any fashion. It is possible to write at a rate where one or more internal ram buffer characters does not always get displayed one for one. That is the display self refreshes at its own frame rate, not knowledgeable about how often the data in any given ram location has changed. In other words the controller is dumb, it has no knowledge of what, when, data has changed in the frame buffer. It just simply regurgitates it mindlessly to the segment lines, this then is asynch behavior to the output.
Regards, Dana.
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18. Re: ADC problem
userc_42486 Nov 25, 2012 3:03 AM (in response to userc_42486)here i am uploading complete work , in which the final output is display of voltage which corresponds to particular glucose level.
test strip interface to psoc:
1) pin 1 refers to working electrode
2) pin 4 refers to reference electrode
3) pin 3 refers to central electrode
here the default output i am getting is 3.17v but after applying blood to the test strip output voltage going to 0.18v which should not happen.
where i am going wrong , how to correct it can anybody help me in this regard.
thanks
prp
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19. Re: ADC problem
DaKn_263916 Feb 10, 2014 3:24 AM (in response to userc_42486)1 of 1 people found this helpfulIf no test strip is attachedPin_1 floating, you should have
1) 400 mV at output of TIA
2) 3.2 V at output of PGA
This should also be true if you attach test stip with no solution ? I am not an expert
on test strip parameterics.
If test strip goes to .18 V Then TIA out should be 22.5 mV, Vout = 22.5 mV = Vref - 40 x Intia,
so Intia (uA) = ( 400 mV - 22.5 ) / 40 =~ 9.4 uA
Is this the current you think you should have ?
This shows for 100 mV ref time response of current, does this jive with your time response scaled
by your ref voltage ?
http://electrochem.cwru.edu/encycl/art-g01-glucose.htm
Regards, Dana.
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20. Re: ADC problem
DaKn_263916 Nov 25, 2012 8:15 AM (in response to userc_42486)Some reference material -
Regards, Dana.
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Blood Glucose.zip 24.5 MB
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21. Re: ADC problem
userc_40557 Nov 25, 2012 8:49 AM (in response to userc_42486)1 of 1 people found this helpful -
22. Re: ADC problem
DaKn_263916 Nov 25, 2012 9:28 AM (in response to userc_42486)1 of 1 people found this helpfulI do not see in your code the drop trigger so that you can generate
the v(t) response as shown ?
Regards, Dana.
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23. Re: ADC problem
userc_42486 Nov 25, 2012 9:14 PM (in response to userc_42486)i didnt understand what is drop trigger?
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24. Re: ADC problem
DaKn_263916 Feb 10, 2014 3:25 AM (in response to userc_42486)1 of 1 people found this helpfulIf you look at the reference material you see a time response
of the drop coming into contact with the sensor, as shown in
this graph. Then an exponential decay as the chemistry of the
reaction proceeds. This reference discusses timing of when to
take your measurement. So you have to time your A/D measure-
ment after you detect the contact of the drop. Discussed in the
various ref material I have sent you.
http://electrochem.cwru.edu/encycl/art-g01-glucose.htm
Regards, Dana.
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25. Re: ADC problem
DaKn_263916 Nov 26, 2012 6:25 AM (in response to userc_42486)1 of 1 people found this helpfulYou can always consider a peak detector to capture the max
value of the response, then digitizing its output, then resetting
it for the next use.
Regards, Dana.
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26. Re: ADC problem
userc_42486 Nov 26, 2012 8:41 AM (in response to userc_42486)here if using peak detector, voltage levels are scaling down i.e if the input to peak detector is 0 to 4 to 0 . the output should be 4v but the output of peak detector is scaling down to millivolts which is not true.how to over this problem?
Thanks
PRP
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27. Re: ADC problem
userc_42486 Nov 26, 2012 8:41 AM (in response to userc_42486)here using peak detector, voltage levels are scaling down i.e if the input to peak detector is 0 to 4 to 0 . the output should be 4v but the output of peak detector is scaling down to millivolts which is not true.how to over this problem?
Thanks
PRP
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28. Re: ADC problem
DaKn_263916 Nov 26, 2012 2:38 PM (in response to userc_42486)1 of 1 people found this helpfulIf you look at response time to peak all peaks oocur ~ 1 sec, your A/D is running
much faster than that, so easiest method is running the A/D continuously and do the
peak detection in software.
If you use an analog peak detection method thats basically stored charge on
a capacitor subject to discharge via leakage currents. You can calculate droop
on a capacitor Q = C x V, I = C dV/dT, dV = ( I x dT ) / C
www.cypress.com/?docID=38360
Regards, Dana.