chip programming thru USB

[Matt]

I have desktop computer and some test program on PC.
Computer is connected with external device over USB.

How can i reprogram the chip thru applikation running on computer applikation. E.g. i want to add new values on in some test program on the chip ( like, instead 1 cycle, user can choose between 2-4 cycles ).

What steps do i have to follow to make this comunication / reprograming work ?

[Guest]

Sorry for typing error :

How can i reprogram the chip thru applikation running on computer. E.g. i want to add new values in some test program on the chip ( like, instead 1 cycle, user can choose between 2-4 cycles ) and then this MCU program should accept this new parameters and continue to work in this new mode...

[A different guest]

You could do this through USB. But I think you are misunderstanding the problem.

The application on the PC 'could' talk to the pic via a number of different protocols. SPI, I2C, RS232, USB, even Ethernet, but you need to make sure your pic can undersand the same protocol.

SPI, I2C and RS232 are easy because they are natively used by the pic.

But the PC doesn't have a dedicated post for SPI or I2C. You can work around that by 'fooling' the parallel port to do this work. But I'd recommend RS232 since the PC is set up for it.

USB and Ethernet are difficult b/c most pics do not 'speak' them natively. So what you can do is put a chip in the middle that converts the signals to RS232 or SPI for example. This is fine, but for most people is way easier, cheaper, and faster just to use RS232 (serial port) from the start.

You could try reading up on bootloaders or RS232-to-pic communication

[iso9001]

If you just want to program and debug then use an ICD. CCS makes one ya know.