Io-Warrior 40 does not respond

GGAVREL · Post by **GGAVREL** » Fri Jan 06, 2006 7:01 pm

After gettting familiar with the IO-24 kit ( successfully ) I switched to the I/O-40 ( needed more I/O) In the design of our product. I am in the process of debugging our prototype and I can't seem to commicate with the I/O 40.
The schematic used is equivalent to the Warrior I/O-40 kit. the layoput has been checked and rechecked and all the grounds and vvc lines are present in the right places( shows 4.78 volts same as at the end of the USB cable )tested with and without the buffers attached. Both the low output and high output were tested
My theory is that there is no clock . pin 21 shows 0 volts and pin 22 shows 4.8 volts and a scope indicates that there is no oscilation. The ceramic resonator used is a TDK (FCR6.0M5) . and the removal of the resonator shows the same voltage.
Another indication is that looking at system devices the IO-40 is identified as a "USB device "with a yellow exlamation mark across it whereas the I/O-24 is indicated as a "USB composite device" which implies to me that the win 2000 USB plug and play does not communicate with the device.

The I/O warrior sample program returns a device not found error.

I am presently at a loss for more ideas about troubl eshooting this device and I would apreciate getting some clues to where to check next.

Note the I/O-40 has been replaced and the ceramic resonator has been replaced , same results

Guido Körber · Post by **Guido Körber** » Sat Jan 07, 2006 12:46 am

The fact that it gets detected just means that the USB has noted that there is a pull up resistor on one of the USB data lines. Please make sure that the 7k5 pull up is really on the D- line.

If the USB host does not properly detect the IO-Warrior it will suspend the port to which it is connected. As a result the IO-Warrior will enter the sleep state, so that might be the explanation why you don't see oscillation.

That is the first thing that comes to my mind.

GGAVREL · Post by **GGAVREL** » Mon Jan 09, 2006 6:59 pm

Thank you Guido for your Reply.
I have verified that there is a 7.5 Kohm resistor between Vcc (pin 40) and USB port D- the rest of the circuitry is Idendical to the schematic for the I/O-Warrior 40 kit with 100 k pull up on pin 3 (p3.7) and 100 K pull up on pin 23 (p0.0) for high power mode.
I do not have the I/O kit only ,the I/O 24 kit. and I was thinking that maybe I should order a I/O 40 kit have this working and compare with our design.

Guido Körber · Post by **Guido Körber** » Mon Jan 09, 2006 7:23 pm

The resonator is a two pin version, the 100nF cap is right next to pins 40 & 39, and Pin 20 has a straight direct connection to pin 39?

GGAVREL · Post by **GGAVREL** » Thu Jan 12, 2006 12:29 am

After getting an I/O warrior 40 kit to compare with the non responding chip we finally found the problem Like for most electronic problems the cause was simple but the diagnostic took a long time. The problem ended up being the reversal of the d- and d+ on our layout ( the spec on the dsub connector must have been mis-interpreted).

The part that made it confusing was that looking at all the voltages both on the kit and our board they were identical voltages , the only difference was one was oscilating and the other was not. because of the same voltage readings it was not evident what was the problem especially that the assumption was that the voltages seen on the D- D+ were coming from the computer, we finally realised that the 3 volts must be generated by the I/O warrior chip because this 3 volts was always on pin 2 wether the D- D+ were inverted or not .
This was another good lesson of not assuming too much.

Guido Körber · Post by **Guido Körber** » Thu Jan 12, 2006 12:11 pm

USB Ports do have 15K pull down resistors internally. Combined with the pull up in the device this results in 3V on one of the data lines which tells the port what speed grade (low or full) device is connected.