Inquiry About Fetching Event Data from GENX320 with OpenMV4-H7-Plus

kwagyeman · April 16, 2025, 5:04pm

Hi, you need to recompile the firmware with this disabled (e.g. set to 0):

boards/OPENMV4P/omv_boardconfig.h

master


      
          #define OMV_OV7725_PLL_CONFIG                 (0x41) // x4
          #define OMV_OV7725_BANDING                    (0x7F)
          
          #define OMV_OV9650_ENABLE                     (1)
          #define OMV_MT9M114_ENABLE                    (1)
          #define OMV_MT9V0XX_ENABLE                    (1)
          #define OMV_LEPTON_ENABLE                     (1)
          #define OMV_PAG7920_ENABLE                    (1)
          #define OMV_PAJ6100_ENABLE                    (1)
          #define OMV_FROGEYE2020_ENABLE                (1)
          #define OMV_GENX320_EHC_ENABLE                (1)
          
          // FIR drivers configuration.
          #define OMV_FIR_MLX90621_ENABLE               (1)
          #define OMV_FIR_MLX90640_ENABLE               (1)
          #define OMV_FIR_MLX90641_ENABLE               (1)
          #define OMV_FIR_AMG8833_ENABLE                (1)
          #define OMV_FIR_LEPTON_ENABLE                 (1)
          
          // UMM heap block size
          #define OMV_UMM_BLOCK_SIZE                    256

The camera driver will then receive events from the event camera and process them to create a frame here:

github.com/openmv/openmv

drivers/sensors/genx320.c

master


      
                  psee_write_ROI_Y(offset * sizeof(uint32_t), 0);
              }
          }
          #endif // (OMV_GENX320_CAL_ENABLE == 1)
          
          static void snapshot_post_process(image_t *image) {
              #if (OMV_GENX320_EHC_ENABLE == 1)
              for (uint32_t i = 0; i < ACTIVE_SENSOR_SIZE; i++) {
                  image->data[i] = __USAT((((int8_t *) image->data)[i] * contrast) + brightness, UINT8_T_BITS);
              }
              #else
              uint8_t *out = fb_alloc(ACTIVE_SENSOR_SIZE, FB_ALLOC_NO_HINT);
              memset(out, brightness, ACTIVE_SENSOR_SIZE);
          
              for (uint32_t i = 0; i < (ACTIVE_SENSOR_SIZE / sizeof(uint32_t)); i++) {
                  uint32_t val = ((uint32_t *) image->data)[i];
                  uint32_t x = __EVT20_X(val);
                  uint32_t y = __EVT20_Y(val);
                  switch (__EVT20_TYPE(val)) {
                      case TD_LOW: {
                          if ((x < ACTIVE_SENSOR_WIDTH) && (y < ACTIVE_SENSOR_HEIGHT)) {

You can find the struct fields for the event here:

github.com/openmv/openmv

drivers/genx320/include/evt_2_0.h

master


      
          * Unless required by applicable law or agreed to in writing, software distributed under the License is distributed
          * on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
          * See the License for the specific language governing permissions and limitations under the License.
          *
          ******************************************************************************
          */
          
          #ifndef INC_EVT_2_0_H_
          #define INC_EVT_2_0_H_
          
          #define __EVT20_TYPE(__VAL__) ((__VAL__ >> 28)& 0xFU)
          #define __EVT20_TS(__VAL__) ((__VAL__ >> 22) & 0xF3U)
          #define __EVT20_X(__VAL__) ((__VAL__ >> 11) & 0x7FFU)
          #define __EVT20_Y(__VAL__) ((__VAL__ ) & 0x7FFU)
          #define __EVT20_TIME_HIGH(__VAL__) ((__VAL__ ) & 0xFFFFFFFU)
          
          #define TD_LOW              0x0U  /*!< EVT2.0 TD Event, Decrease in illumination   */
          #define TD_HIGH             0x1U  /*!< EVT2.0 TD Event, Increase in illumination   */
          #define EV_TIME_HIGH        0x8U  /*!< Timer High bits                             */
          #define EXT_TRIGGER         0xAU  /*!< External triggers                           */
          #define OTHERS              0xEU  /*!< To be used in extension in the event types  */

See the TS value.
…

We do not recommend to do this though. It’s incredibly taxing on the CPU to generate an image from random access events.

If you are not interested in processing the event image as an image but processing events as they come in… you are welcome to modify the firmware as you like to do whatever you want. Note that the camera driver will buffer 25600 events before processing them. To change the buffer depth will require serious modifications of the frame capture DMA system which is completely non-trivial.

…

Instead, we recommend just setting the frame rate you want. Which defines the integration time as 1/fps, and then processing the full frames. The H7 Plus can run up to 375 Hz which should be more than enough to have very good temporal resolution.

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Inquiry About Fetching Event Data from GENX320 with OpenMV4-H7-Plus

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