ads7846_sync
static uint32_t ads7846_sync(int, int, uint32_t);
(void)ads7846_sync(0, 1, cmd);
(void)ads7846_sync(1, 1, cmd);
pos->y = ads7846_sync(1, 1, cmd);
pos->x = ads7846_sync(1, 1, cmd);
z0 = ads7846_sync(1, 1, cmd);
z1 = ads7846_sync(1, 0, cmd);