Thanks. Millisecond is good for me. Every signal (1 and 0) sent is triggered by a user program. The period the signal lasts is not so important either. Yuyang -----Original Message----- From: Xiaofan Chen [mailto:xiaofanc@xxxxxxxxx] Sent: Thursday, January 24, 2013 10:54 AM To: Du, Yuyang Cc: linux-usb@xxxxxxxxxxxxxxx Subject: Re: USB host port acts like a signal generator On Thu, Jan 24, 2013 at 10:44 AM, Du, Yuyang <yuyang.du@xxxxxxxxx> wrote: > My intent is really special, I don't know whether I missed something, > but all the articles about writing a USB driver do not address my > need. > > I want to use the USB port on the host as a signal generator to drive > a USB cable (the two data lines) connected to another device's USB > connector. The generator just needs to output 1 or 0 (high or low > signal) as controlled by a user space program. > > What should I do? Could you please help me? I am not so sure if it is really possible to do what you want to do. Even if we assume yes that there is a way, how good the timing accuracy you want on the signal? Remember the typical Linux OS is not an RTOS, so you will not be able to get very good timing. Even if you use a RTOS extension, I am not so sure if you can get us accuracy. So in reality, a cheap USB MCU can do way better than the host and you should do that using a USB MCU. -- Xiaofan -- To unsubscribe from this list: send the line "unsubscribe linux-usb" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
