Hi, I am a newbie.I want to implement spi in between my arm board arm7 ( mcb2140)and another chip called pn544. I have read the user manual www.nxp.com/.../UM10139_1.pdf. ----------------------------------- SPI Clock Counter Register (S0SPCCR - 0xE002 000C) This register controls the frequency of a master’s SCK. The register indicates the number of PCLK cycles that make up an SPI clock. The value of this register must always be an even number. As a result, bit 0 must always be 0. The value of the register must also always be greater than or equal to 8. Violations of this can result in unpredictable behavior. The SPI0 rate may be calculated as: PCLK / SPCCR0 value. The PCLK rate is CCLK /VPB divider rate as determined by the VPBDIV register contents. ------------------------------------- But one thing that is not clear to me is how do we calculate SPI Clock Counter Register? What is the value of CCLK,VPBDIV and how do we detemine SPI0 rate for microcontoller lpc2148.Please explain me is simple way . Thanks