Question concerning FPU-co

Yojimbo

I was just reading over some of the documentation on the FPU math co-proc and I was wondering, when used with a Javelin, do I need to construct some UART objects to handle the data or is it taken care of by com.micromegacorp.math.v2_spi.*? Just trying to puzzle out why I can't get it (FPU) to recieve a reset command. Thanks!

Peter Verkaik

Have you checked the uM-Fpu javelin support here:

http://www.micromegacorp.com/javelin.html

version 1.1 Fpu shows:

* V1.1 - September 21, 2005

* - corrected bus assignment in reset method



regards peter




Post Edited (Peter Verkaik) : 12/21/2005 12:12:32 AM GMT

Yojimbo

Well, I updated, but it seemed to have no effect. I uploaded the Graph.java program to the Javelin but all I get is:

Graph
uM-FPU not responding.

I'm fairly certain I have it hooked up properly though (though I do not have a DS1620 thermometer, it should still be able to reset the FPU).

Using the SPI hookup, I have FPU.pin1(CS) wired to pin4 (VSS) and then to ground (Vss). Pin2 has a 1k resistor to pin5 with a wire between them(pin 5 and the 1k resistor that is) going to P14(Javelin). Pin3 goes straight to P15 (Javelin). Pin6 leads no where. Pin7 grounds (Vss) and Pin8 has 5v @ Vdd.

The only other thing hooked up to the BoE are two servos, which I don't even enable while trying to run Graph.java.

Any ideas would be really appreciated. Thanks!!

-Sean

Peter Verkaik

You have the javelin GND and Fpu GND connected, as they must?

Please post your code.

regards peter

Yojimbo

I think it's grounded properly, I have it wired just as the diagram describes for SPI in the javelin FPU-co PDF linked here (page 2). The code I am using is stock, and attached. Though I am not what you meanwhen you refer to the Javelin being grounded, it is resting in it's socket.

Peter Verkaik

Ok, the Fpu reset starts with toggling javelin pins 14 and 15.
Have you checked if both these pins actually become low outputs?

Try·this:

static void main() {
· CPU.writePin(CPU.pin14,false);
· CPU.writePin(CPU.pin15,false);
· while (true) ;
}

If you run this test program you·can check the pin voltages.
Between each pin and +5V·you must measure 5V. These pins also
must be able to light a LED via 1k resistor to 5V.

If either pin is not low, then you must use other pins for Fpu.

regards peter

Yojimbo

Thank you thank you thank you thank you thank you!!!
I didn't actually get your code to compile, it said Syntax: Unexpected input discarded, however, I went ahead and changed the pins in FPU.java in the v2_SPI folder and physically changed it as well and poof! It works! Thank you!!! Now I can finally do sigmoid functions that my neural net will need (as soon as I puzzle that out! heh). Thank you!!

-Sean

Peter Verkaik

Great that it works.
You should find out at some time if your javelin pins 14 and/or 15 are damaged.
Because you changed pins and did not check 14 and 15 (did you?) it could
also have been·a faulty wire connection.

regards peter