Вам подойдут режимы 0 или 3 -
Код
spcr_val [spispeedindex][SPIC_MODE0] = (0U << CPOL) | (0U << CPHA) | spcr;
spcr_val [spispeedindex][SPIC_MODE1] = (0U << CPOL) | (1U << CPHA) | spcr;
spcr_val [spispeedindex][SPIC_MODE2] = (1U << CPOL) | (0U << CPHA) | spcr;
spcr_val [spispeedindex][SPIC_MODE3] = (1U << CPOL) | (1U << CPHA) | spcr;