User`s guide

www.ti.com

Software

CDC and HID-Datapipe provide the developer a simple data exchange interface. As a brief example of

this interface, a simple application follows.

VOID main(VOID)

{

// Init clocks, power, ports

WDT_A_hold(WDT_A_BASE);

PMM_setVCore(PMM_BASE, PMM_CORE_LEVEL_2);

initPorts();

initClocks(8000000); // CPU frequency, in Hz

initTimer(); // Set up one-second intervals to wake from LPM0

USB_setup(TRUE,TRUE); // USB API call; initializes USB and connects to the host

__enable_interrupt();

while (1)

{

__bis_SR_register(LPM0_bits + GIE); // Enter LPM0 sleep

if (cdcSendDataInBackground(helloWorldStr, 12, CDC0_INTFNUM, 1000))

{

handleFailedSend(); // Might fail if cable is disconnected, bus is

// busy, or host has become unresponsive

}

This application wakes up once per second (using a timer interrupt, not shown) and sends a string over

USB to a virtual COM port on the host.

To send data over a CDC interface (to a virtual COM port), you can simply build the interface with the

Descriptor Tool, prepare your data, and call the API construct function cdcSendDataInBackground(), which

accepts these parameters:

• Data buffer

• The buffer's size

• Which CDC interface

• The number of retries before the attempt is considered a failure.

This is only one simple example; much more is possible with the USB API. See the MSP430 USB API

Programmer's Guide and examples in the MSP430 USB Developers Package for more information.

SLAA457A–September 2013–Revised May 2014 Starting a USB Design Using MSP430™ MCUs

Submit Documentation Feedback