I don't want to design from scratch as this is a 1 off for one customer. I am looking for a device which performs the following.
USB connection to a Windows PC
Output resolution needs only to be 8-bit, any more is a waste.
The output is to be PWM of a few tens Hz to 1 or so kHz
Duty cycle does not need to go down to zero and needs to reach full resolution before 100% duty cycle.
This output will drive an opto for HV (800volt) isolation.
Application is basically DC output
PC software is a must, that looks at least a bit professional
External digital outputs may be useful in future but not necessary
Price should be below $100