In SX Microcontrollers, SX/B Compiler and SX-Key Tool, jmokie wrote:

First time SX user, not familiar with machine code, former STAMP user and a electronics hacker needs help.  

I'm trying to use the a/d method in the sample code for the SXB on an SX28AC to read the output of a line sensor output to do PID control on the motors of my robot.  I'm using the Vishay TCRT5000 reflex detector.  The code is straight out of the example

 

I am trying to scale the output in a usable range.  The ckt is attached.

Right now with the resistors shown, the transistor collector reads: 
0.181 vdc with white resulting in .48 ma

3.08 with black resulting in .192 ma

Which sounds like a good range. But the a/d, monitored with the Watch/Poll command in the Debug mode, starts counting at 0 or 1 @ 0.3vdc on the collector and reaches 240 @2.67 vdc, which is really dark grey.  

I would like to have 0 counts = white and 255 = black

My sensor has the emitter tied to gnd on the ckt board, so putting another resisor in the emitter ckt means more cut-n-kludge.  Hoping for some advice that will give a better range in counts.

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