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CFA635 Drivers


New member
I have a CFA-635 6-button module and was able to get it working great under XP with the software that was included. The ultimate goal for this module is to place it in a medical design where an FPGA will be controlling the module. I have just begun development for this and I am at the stage of getting the default factory "welcome screen" to show up when I plug the USB cable into my board. I was expecting the message to display as long as there was 5V on the VBUS line but that is not the case.

Is there some type of initialization packet that needs to be sent to the module to get it to execute the current Boot State? I noticed that the message doesn't appear when plugged into a PC that doesn't have the drivers installed either. Is there something in the drivers that is done when a connection of a 635 module is recognized on a USB port?
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CF Support2

The way that the USB hardware is designed is that it will not take power from the system until the system tells it that it okay to do so -- which is typically after the driver loads.

CF Tech

If you are going to use an FPGA, you might want to use a "logic level serial" version of the module. A UART would be a lot easier to implement than a USB host.

The serial version also side-steps any power issues.


New member
That makes sense. I figured that was the case. I was hoping to port the drivers over to the FPGA but using an RS-232 port works out even better. Our board has two dedicated ports and even our USB is a UART at the FPGA level and converted to USB in the transceiver.

Thanks for you help!