Have you tried with ADC Continuous mode of operation ?

I 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...

I 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.
 

If 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.

Some reference material -

Regards, Dana.

this might help you out in designing of blood glucose meter

http://www.cypress.com/?rid=43661

I do not see in your code the drop trigger so that you can generate

the v(t) response as shown ?

file:///C:/Users/Dana/Documents/1%20Cypress/Ap%20Notes/Blood%20Glucose/Electrochemistry%20Encyclopedia%20--%20Electrochemical%20blood%20glucose%20test.htm

Regards, Dana.

If 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.

You 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.

If 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.