USB development

[johogee]

I am looking for resources for beginners to understand USB development using NXP products.  I've worked with serial data before but not at such a complex rate as USB.  Most of my serial data experience is with aircraft serial data and RS-232 development. 

I have been using the NXP FRDM-K22F development board USB examples to understand USB development.  I have been using the step into function on the MCUXpress debug section to analyze each line of code.  This is a slow and tedious task.

Right now I am using the NXP FRDM-K22F development board to buffer serial data from a UR5 Universal Robot at a baud rate of 125 to a RS-232 baud rate of 115,200.  The baud rate of 115,200 is required by the NCD.io WIRELESS RS-232 MODEM.  Since the RS-232 baud rate is so slow I have been able to use GPIO's to development my own protocols.  

I'm exploring the USB interface to be modified to tap into the Universal Robot data stream.

Thanks for any help.

[xiangjun_rong]

Hi,

I suppose that it is okay for K22 to generate 250 baud rate.

The K22 uart receiving clock frequency will 250*16=4KHz, if you use 250 baud rate. For K22, the uart0/uart1 use system clock as it's driving clock, the uart2,uart3... use bus clock.

let's compute the maximum system clock frequency, which the uart0 is used to communicate with 250 baud rate, based on the following baud rate formula.

the maximum system clock is 8191*16*250=32.764MHz.

You can use uart to communicate with UR5 Universal Robot with 250 baud rate and RS232, the RS232 just uses transceiver to get high logic voltage to reduce the error rate.

You can use USB with CDC class to get virtual COM to communicate with PC or the usb host.

Hope it can help you

BR

XiangJun Rong