MSP 430 - Getting started guide ... Configuring Clocks on MSP430. ... //This small set of code takes care of an inconsistency between g2553 and g2231. It should be ... To enable SPI we need to make the pins for MISO, MOSI and CLK in peripheral mode so USCI will control them. We then configure a custom pin such as P1.5 above, to be the SS or CSn. Looking at the port schematics in the G2553 datasheet we can see that to make the pins work with USCI we need to set Both P1SEL and P1SEL2 to ‘1’. Your Energia coding is right. but you need to add some additional at commands to send sms using gsm module.below i provide the modified code. and call the sendsms() function in setup() function for send sms only once when you push reset button. if it is in loop() function without any condition then the gsm module send sms continously. The G2553 chip has two Timers and thus two sets of registers to use them. As far as the CPU is concerned, one set (Timer0_A3) can be accessed at 0x012E, 0x0160-0x0166, and 0x0170-0x0176. The other set (Timer1_A3) can be accessed at 0x011E, 0x0180-0x0186, and 0x0190-0x0196.