Hi. I’m using the Arduino USB board as a hardware platform for teaching embedded systems. I’m working with straight C code, not the
Arduino environment or the bootloader. I’d like to be able to use the serial port stand-alone. Is there a way to disable the USB chip? Preferably in software, altho I’ll take any other suggestions. Thanks.
Hi There,
If your not using the development environment, and especially the bootloader should you really be using the arduino board?
It is extremely easy to build an AVR development board, all it really requires is an oscillator (if the timing of the onboard is not sutiable for application), a cap across vcc and gnd nets and an icsp header (which can be connected to an RS-232 with a couple of diodes and resistors (or just program from an icsp programmer).
Just my thoughts,
TalkingJazz
I’ve hacked together quickie processor boards pretty often (in fact, I have a project in the works using the 328P), but I’m using the board as a teaching tool. A friend of mine uses the Arduino boards for work pretty regularly as simple AVR boards after getting rid of the boot loader, etc. If I’d realized the USB was tied to the serial port I probably would hve gone for a board without the USB. but at the moment, I still have the problem of disabling the USB interface so I can use the serial port.
I’m not following where the problem lies. The USB is parallel to the serial ports, you can use them and just ignore the USB, unless I’m missing something entirely. The same data goes to the RX and TX pins as to the FTDI USB interface.
(You also realize, of course, that it’s TTL serial, right?)
–A
Yes, I realized the Tx and Rx pins were brought out. I was concerned that the USB chip might load down the Tx lines if it was active and I tried to just use the Tx line. If that’s not the case, then I’ve just driven myself nuts for no reason. It wouldn’t be the first time. 
So all I’d need to do is throw an RS232 driver on the Tx and Rx pins in that case.
Lee
Yes, indeed. Shouldn’t be a problem at all. BTW, the same applies to the Arduino BT and its WT11 BT module.