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Newby question


Hi all,

I am struggling with a little problem and I am sure that it is because I am new to this…

I have built a board with a USBizi 100 chip and it works fine when set to be a


but as soon as I change it to a


it has a paddy…

Now I have looked high and low to change the debug interface and all the docs point me to the Mode and BL pins. But looking through the docs on this when I jumper the BL to Gnd then it doesn’t run my app it just goes to the bootloader. When I jumper the Mode Pin to Gnd it turns off the USB and routes everything to the COM port.

How do I get the StartCDC to work on a USBizi system???

Thanks in advance,



To use CDC, you need to have debugging switch to serial, using MODE pin. Note that the serial RX pin can’t be left floating when you debug over serial.

Please note that StartCDC_WithDebugging is no longer supported but you are more than welcome to use it if it fits your needs.

Welcome to the community.