Coverting ASCII code to value

[sbscott]

I am using a MaxSonar module to determine distances with a 28x2. I capture the code but not sure how convert it to a value I can do something with. The plan is to use this to determine a "clear path" for the object-avoiding bot.

The output is an ASCII capital “R”, followed by three ASCII character digits representing the range in inches up to a maximum of 255, followed by a carriage return (ASCII 13). The baud rate is 9600, 8 bits, no parity, with one stop bit.

After reading some threads, I am still not clear on this. I tried new code

h:
debug
serin a.3,n9600,("R"), b0,b1,b2
w0 = b2 * 10 + b1 * 10 + b0 - 5328
pause 400
goto h

If w0 is the decimal value, it does not make sense. Where am I going astray here?

 

[BeanieBots]

b0 and b1 are the two bytes which make up w0. So your calculation is mucking up your original values.
Try replacing w0 with a word variable that does not include the bytes you are using. eg w2.

 

[sbscott]

I changed w0 with w4 but I still don't see useful values yet...

 

[Andrew Cowan]

If you want to input ascii, you'll need to use:

serin a.3,n9600,("R"), #b0,#b1,#b2

 

[eclectic]

Where did the equation

= b2 * 10 + b1 * 10 + b0 - 5328


come from??

e

 

[sbscott]

got it from:
http://www.picaxeforum.co.uk/showthread.php?t=5018&highlight=converting+ascii+decimal

 

[westaust55]

Also had a look at one of the MAXSonar module datasheets (would be nice if folks gave a link to the exact unit being used) and there was no indication as to which digit units or hundreds as sent first.
The sheet I looked at just states:
“The output is an ASCII capital “R”, followed by three ASCII character digits representing the range in inches up to a maximum of 255, followed by a carriage return (ASCII 13).”

If this was intended by the manufacturer to go straight to a display I would have thought the first ASCII character was the hundreds digit.

So you might also try:

h:
debug
serin a.3,n9600,("R"), #b0, #b1, #b2
w4 = b0 * 10 + b1 * 10 + b2
pause 400
goto h

 

[hippy]

The output is an ASCII capital “R”, followed by three ASCII character digits representing the range in inches up to a maximum of 255, followed by a carriage return (ASCII 13).

I'm not sure why ...

SERIN A.3, N9600,("R"), #b0

wouldn't work, and I could have sworn that's what you originally had in post #1 but I really can't remember now !

 

[sbscott]

I am happy to report that westaust55's suggestion worked! I now have the ability to do some ranging with my bot. Now to figure out how it integrate it into the overall operation.

I will start a new post once I get the critter running.

Thanks as always!

 

[westaust55]

Great to see/read that you have it working.
Don't forget to provide a link to your external hardware in future for ease of others helping you.