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AD speeds

Posted: Mon Feb 11, 2013 2:07 am
by YahooArchive
Got the A/D function working. I'm finding that the fastest I can make the Pro
Plus do a convert and report it is about 3 milliseconds. That seems slow, but I
don't see a spec to check. Here is my test program:

for i=1 to 100
print AD(2)
next i

It takes about 315 milliseconds to do 100 reads, no matter what baud rate I run
at. I have it smoking along at 921.6 Kilobaud, leading me to suspect the biggest
delay is A/D conversion.

Is 3 milliseconds about right or can it be sped up any?

George

Re: AD speeds

Posted: Mon Feb 11, 2013 2:07 am
by YahooArchive
The product info page for the Pro Plus says the A/D speed is 200 KHz. That's 5
microseconds. I'm getting 3 milliseconds, not microseconds. Could the holdup be
in the host PC, not acknowledging the reads fast enough?
George

Re: AD speeds

Posted: Mon Feb 11, 2013 2:08 am
by YahooArchive
I deleted the PRINT function and got A/D conversions in 14 microseconds. That's
fast. Here is the test program:

for i=1 to 1000
b=ad(2)
next i

So I make a read, do nothing with it, and make another read, up to 1000 of them.
Took 14 milliseconds to do 1000 reads. That's 14 microseconds for the read plus
the for/next looping. by adding the PRINT function, the 14 microseconds grew to
3 milliseconds, even at 921.6 kilobaud on the com port.

I'm hoping there is a way to speed up the printing. ??

George

Re: AD speeds

Posted: Mon Feb 11, 2013 2:09 am
by YahooArchive
AD conversion rates on the LPC2103 are about 10 micro-seconds, so that checks
out.

I did not see in your program where you changed the baud rate, with a call to
BAUD0 or writing directly to the registers.

Setting baud rate with the Windows Device Manager has NO affect on the baud rate
in BASICtools or TclTerm/MakeItC.