Using Basic Atom Pro with Sharp GP2D12 IR Sensor

Here is a listing of code used in the Midnight Prowlerbot for handling the Sharp GP2D12 infrared sensor readings.

'Infrared module - GP2D12 IR Sensor available from Lynxmotion
IR_LDat con P16 'AX2 (analog)
IR_RDat con P17 'AX3 (analog)

'Infrared reading conversion - this module is not linear and this compensates for it
IRconverttable bytetable 80,80,80,80,80,80,80,80,80,78,76,74,72,70,68,66,64,62,60, 59,58,57,55,53,52,51,50,49,48,47,45,43,42,41,40,39,38,37,35,33,
32,31,30,30,29,29,28,28,27,27,26,26,26,25,25,25,24,24,24,23,
23,22,22,21,21,20,20,20,19,19,18,18,18,17,17,16,16,16,15,15,
15,14,14,13,13,13,12,12,11,11,11,10,10,10,10,10,10,10,10,10

GetIRDistance

adin IR_RDat, IR_RRaw
IR_RFcms = tofloat(IR_RRaw) / 5.12
IR_Rcms = IRconverttable(toint IR_RFcms)
if IR_RRaw > 512 then
IR_Rcms = 99
endif

adin IR_LDat, IR_LRaw
IR_LFcms = tofloat(IR_LRaw) / 5.12
IR_Lcms = IRconverttable(toint IR_LFcms)
if IR_LRaw > 512 then
IR_Lcms = 99
endif

return

Notice that IR_RDat and IR_LDat do not use analog in pins that might be expected - they are using P16 and P17, not AX2 and AX3 as would be used on a Basic Atom. When I used AX2 and AX3, or even just 2 and 3 as in the manual, I couldn't get the sensors to work at all. Little did I realize that the adin command prefers a 'P' identified pin to work.

Since I rarely look for information on a device before using it, other than the manual or device sheet, I had no idea that the adin command had a quirk. It was after hours of frustration that I found a post on the Lynxmotion forums at http://www.lynxmotion.net/viewtopic.php?t=570&highlight=gp2d12 that described the pin identification problem.

Incidentally, the pin identifiers are mentioned in the Basic Atom Pro manual under the adin description, but what isn't mentioned is that if an 'AX#' identifier is used instead of a 'P#' identifier that the adin command will not work; however, the 'AX#' identifier works fine with the adin command on the Basic Atom non-Pro.

Oddly, I've had identifier issues with other commands also. It appears that using an assigned constant to identify a pin, such as using IR_RDat to identify P17, does not always work. For instance, serin does not seem to work with assigned constant identifiers, but works fine with 'P#' identifiers. Unfortunately, there is no indication that things aren't working as the code compiles and programs just fine.

I've even had a similar issue come up with 'if' statements only to find that not using an assigned constant identifier fixed the non-working code. This type of thing has happened on several occassions and failing to be aware of it caused frustration nearly to the point of forcible hair removal and uncontrollable mumbling. By the way, the identifier bug was on version 8.0.1.0 of the IDE. I'm not sure if it exists in the latest version.