Got a strange problem here. When I power up, the platform PROM starts up the Spartan 3 OK and a Cypress FX2 (USB2). However when I shoot another program down through the JTAG cable, there is a slight dip in the FX2 reset pin, which I connected to a Spartan IO, from about 3.3V to 2.2V. This slight dip in voltage seems to hose the FX2 chip and its oscillator will not come back on. I thought that the IOs during the programming cycle of the Spartan 3s were high impedance and I shouldn't see such a dip.
In retrospect, I should have wired the Cypress FX2 Reset pin to an RC network like the data sheet says. But instead I wanted to be able to start the FX2 after things were stable with the Spartan 3. Another issue is why the FX2 won't recover, even if I cycle the reset pin, but that question I will direct to the Cypress folks.
Any help here would be appreciated.
Thanks in advance,
b r a d @ a i v i s i o n . c o m