#define REG_RUN 0x00 /* Read capture status, write start capture. */
#define REG_PWM_EN 0x02 /* User PWM channels on/off. */
#define REG_CAPT_MODE 0x03 /* Write 0x00 capture to SDRAM, 0x01 streaming. */
+#define REG_PIN_STATE 0x04 /* Read current pin state (real time display). */
#define REG_BULK 0x08 /* Write start addr, byte count to download samples. */
#define REG_SAMPLING 0x10 /* Write capture config, read capture SDRAM location. */
#define REG_TRIGGER 0x20 /* Write level and edge trigger config. */