5.2.1 Low-Level Initialization

For the low level initialization the MCU is initialized in MCU_init() by setting the MSP430F5529 main clock frequency to 25 MHz. The TRF7970A hardware connections and the MSP430F5529 SPI module (SPI clock running at 4 MHz; minimum recommended is 2 MHz) is initialized in TRF79x0_init(). The variables in Example 6 are needed for the COM port transmit and receive and the card emulation stack initialization. The Buttons_init function set the GPIO direction to inputs and the Buttons_interruptEnable() function enables the interrupt for buttons S1 and S2.