Texas Instruments MSP430 Student Guide

Lab 7c – CDC ‘Simple Send’ Example
24. Once you are done watch time go by: disconnect the Terminal; Terminate the
debugger (if you didn’t do it in the last step).
25. (Optional) Review the code in this example. Here’s a bit of the code from main.c:
VOID main(VOID)
{
WDT_A_hold(WDT_A_BASE); //Stop watchdog timer
// Minimum Vcore required for the USB API is PMM_CORE_LEVEL_2
PMM_setVCore(PMM_BASE, PMM_CORE_LEVEL_2);
initPorts(); // Config GPIOS for low-power (output low)
initClocks(8000000); // MCLK=SMCLK=FLL=8MHz; ACLK=REFO=32kHz
USB_setup(TRUE,TRUE); // Init USB; if a host is present, connect
initRTC(); // Start the real-time clock
__enable_interrupt(); // Enable interrupts globally
while (1)
{
// Enter LPM0, which keeps the DCO/FLL active but shuts off the
// CPU. For USB, you can't go below LPM0!
__bis_SR_register(LPM0_bits + GIE);
// If USB is present, send time to host. Flag set every sec.
if (bSendTimeToHost)
{
bSendTimeToHost = FALSE;
convertTimeBinToASCII(timeStr);
// This function begins the USB send operation, and immediately
// returns, while the sending happens in the background.
// Send timeStr, 9 bytes, to intf #0 (which is enumerated as a
// COM port). 1000 retries. (Retries will be attempted if the
// previous send hasn't completed yet). If the bus isn't present,
// it simply returns and does nothing.
if (cdcSendDataInBackground(timeStr, 9, CDC0_INTFNUM, 1000))
{
_NOP(); // If it fails, it'll end up here. Could happen if
// the cable was detached after the connectionState()
} // check, or if somehow the retries failed
}
} //while(1)
} //main()
// Convert the binary globals hour/min/sec into a string, of format "hr:mn:sc"
// Assumes str is an nine-byte string.
VOID convertTimeBinToASCII(BYTE* str)
{
BYTE hourStr[2], minStr[2], secStr[2];
convertTwoDigBinToASCII(hour, hourStr);
convertTwoDigBinToASCII(min, minStr);
convertTwoDigBinToASCII(sec, secStr);
str[0] = hourStr[0];
str[1] = hourStr[1];
str[2] = ':';
str[3] = minStr[0];
str[4] = minStr[1];
str[5] = ':';
str[6] = secStr[0];
str[7] = secStr[1];
str[8] = '\n';
}
7 - 40 MSP430 Workshop - USB Devices

Texas Instruments MSP430 Specifications

General

Brand	Texas Instruments
Model	MSP430
Category	Microcontrollers
Language	English