GP2
bus_space_write_1(bst, bsh, GP2, MDC_LOW);
bus_space_write_1(bst, bsh, GP2, MDC_HIGH);
bus_space_write_1(bst, bsh, GP2, bit | MDC_LOW);
bus_space_write_1(bst, bsh, GP2, bit | MDC_HIGH);
bus_space_write_1(bst, bsh, GP2, MDC_LOW);
x = bus_space_read_1(bst, bsh, GP2);
bus_space_write_1(bst, bsh, GP2, MDC_HIGH);