2-CH Swept Voltage Analyser

Michael 2727

Senior Member
Just a thought at the moment -

<code><pre><font size=2 face='Courier'>Main:
' debug
readadc10 1, w0
readadc10 4, w1
inc w3
if w3 = 1000 then Ramp
pwmout 2, 249, w3
goto Main:
' debug
readadc10 1, w0
readadc10 4, w1
dec w3
pwmout 2, 249, w3
if w3 = 0 then Main
goto Ramp </font></pre></code>

You will need an RC network to smooth out
the voltage.

All it needs now is for some clever person
to work out how to export the w1,w2 and w3
points to Excel etc.
Or just remove the READADC10s and watch the
LED fade up and down ~ ;o)

Michael 2727

Senior Member
In case anyone was interested -
<A href='http://porepunkahps.vic.edu.au/home/jef01/files/display/2_Ch_Swept_Voltage_Analyser_Logger.htm' Target=_Blank>External Web Link</a>

I just need to sort out the best RC values
to use.


New Member
There was a posting just a few days ago titled &quot;New Excel data import software &quot; that has a link to a freeware excel addin that will allow your picaxe program to send data values to a worksheet vis a serial link. Pretty simple utility that does the job.


Michael 2727

Senior Member
Very good Lefty,
That was going to be my next post question ~:eek:)

I have never used Serout, Sertxd etc, before.
And the Terminal App, so this is all new to me.

I have also just updated the .htm page to
include some notes on the RC network.
And to clarify a couple of other things.


Senior Member
Mike, the following example may help you get started with SelmaDAQ.


setfreq m8 '8Mhz operation gives 9.6Kbaud sertxd
pause 1000
sertxd (&quot;CLEARDATA&quot;,CR)
pause 1000
sertxd (&quot;LABEL,&quot;,&quot;,X,Y,Z&quot;,CR) 'Note extra &quot;,&quot; to skip time column
pause 1000
sertxd (&quot;MSG,SelmaDAQ Ramp Test.&quot;,CR)

for b0 = 0 to 128
b1 = b0/2
b2 = b0*2
sertxd (&quot;DATA,&quot;,&quot;,&quot;,#b1,&quot;,&quot;,#b0,&quot;,&quot;,#b2,CR)'Note extra &quot;,&quot; to start data in column B


Michael 2727

Senior Member
Thanks Xstamp,
I only got errors when trying out SelmaDAQ,
along the lines of, Error: &lt; ASCII = 10 &gt; or
ASCII = 200.

As I said I have never played with this side
of Picaxe before, still learning ~ :eek:)
I will fumble around with it later.

By the way, what is the buffer size in the
Treminal App ?. I can only seem to capture
around 140 lines before it overflows.
And it does seem to vary a little ?



Senior Member
I have not seen any buffer overflow errors at 9.6kbuad but sometimes have to use multiple CR commands (and pauses) when sending setup information. However, once SelmaDAQ has accept the setup information data export is rock solid every time.

I am sure you have already done it, but take a look at the very good documantation.



Senior Member
The display buffer is probably 2K cut in half back to 1K when it's full, or something like that.

In my own programs I often use 4K with cut-back to 3K for Terminal display. They're not designed for mass data capture, and having a big buffer ( holding things most will never want to go back and look at ) is quite wasteful, and also limits the responsiveness at faster baud rates leading to problems.