Last year I took an electronic device that was connected to a computer via a Dongle that sent information from the board via Serial TTL to a USBdongle. The dongle contained the VID/PID id and converted the device Serial TTL output to USB via a Maxim chip. We cut the cable carrying the serial data and via a radio sent the information to a 2nd radio and then connected the Serial TTL side of the dongle . The dongle was plugged in and like http://
the device wireless. Works well and can be updated without taking the computer to the device.
NOW I have another electronics board I want to do the same thing with except that it has a EZUSB chip on board the electronics device. This is my approach so far.
I have connected an FTDI USB to SERial TTL cable to the isolated the communications lines (TX and RX) of the microprocessor that go to the EZUSB chipo. I have set the FTDI USB cable to the correct VID/PID id (confirmed by checking device id) and tried to communicate with the device. When the cable is connected to the electronic device and the USB cable is inserted, using either XP or Vista, the computer recognizes the device and tries to load the correct driver (fails 50% of the time). Even when the driver loads I cannot connect to the device (software says "cannot wakeup device" (i have the usb wakeup enabled in the FTDI setup))
Finally, my questions:
1. Am i crazy for thinking I could get this to work?
2. What obvious things am I missing here?
( I have modified the ini files of the software that drives the device to include the drivers for the FTDI chip )
3. Could it be the connection speed of the micro-controller and the usb-serial are not correct? (i am running the connection speed of the FTDI cable at 119K but how do i determine the comm speed of a microprocessor (ie clock speed, based upon crystal used) I'm obviously not an hardware engineer)
Thanks for any help at all.