EPC635 datasheet(55/97 Pages) EPC

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7.3. 3D TOF distance measurement flow

A final 3D TOF distance image will be done with different process steps according to Figure 51. Both interfaces of the epc635 are used:

The I2C for configuration, mode selection and temperature reading (blue marked in the following figures) and the high-speed TCMI for

reading the frame data (red marked in the following figures).

The sequence starts with the initialization of the epc635 registers with the necessary and correct configuration parameters. Next, the TOF

measurement with the expected mode (sine 4x DCS, or 2x DCS) will be performed. Depending of the application and the ambient condi-

tions (ambient-light, changing temperature conditions), the TOF measurement needs some compensation. For the purpose of more accu -

rate ambient-light compensation, a grayscale measurement without illumination captures the background light level. Reading of the on-chip

temperature sensor (from time to time) helps to compensate thermal influences caused by e.g. the LEDs, the optical filters and the epc660

chip. After the rearrangement of the grayscale image to the correct pixel orientation, the final 3D TOF distance image can be calculated

with all for the application necessary compensations.

Perform TOF measurement

Perform black & white measurement

CPU on I2C: Initialization epc635

START TOF measurement

CPU: Calculate TOF distance image

CPU: Arrange greyscale image

Next TOF measurement

Stop

END TOF measurement

CPU on I2C: Read Temperature

Figure 51: Generic 3D TOF distance measurement flow

The process flows for distance measurements and for grayscale images are similar, see Figure 52. The main differences are the mode se-

lection, see Table 32 and depending thereof the number of frames, which need to be read out during a process cycle. After mode setting,

the cycle will be started by applying the SHUTTER signal. Once the SHUTTER is stimulated, the epc635 executes the measurement until

the end of the sequence automatically. The application CPU has to follow accordingly by reading out the collected data until the end of se -

quence.

Characteristics subject to change without notice

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Datasheet_epc635-V1.02

EPC635 データシート(PDF) 55 Page - Espros Photonics corp