By using a RP2350 to directly interface with the ADC found on the sensor assembly it allows for high quality data capture and direct control over exposure. To store the data a SD card is used which allows for high speed data storage using the 4-bit SDIO protocol.
The camera can be used un-tethered unlike other scanning camera's where a computer is used to control the scanner and store the data. As the RP Pico 2 used in this project has a limited amount of pins the camera is controlled using a web interface hosted on the camera itself.
So it is not completely independent but that might change in the future.
Using the web based control panel the scan angle and exposure time can be set. It also allows for the user to preview the photo by streaming a binned and compressed version of the photo to the users browser. Instead of repeatedly previewing and focusing the camera the user can select a line in the preview where the user wants to focus on. The camera then moves to that location and captures that line continuously. It then determines the sharpness by calculating the contrast comparable to a contrast auto-focus. This sharpness metric is then send to the user where it can be used to quickly move to lens to the optimal focus.
After composing and focusing the user can decide to capture the photo which then will be saved to an SD card as a linear uncompressed 16-bit per
color tiff file. Currently it is not possible to save a full size image as a JPEG due to ram constrains. This tiff file is like an raw image and still needs to be processed by shifting lines, dark count subtraction and gamma correction.
The panorama mechanism uses a 3d printed base that mounts to a tripod. It houses a geared stepper motor and a rotating platform connected to the base by two large diameter deep groove bearings. On top of the platform a camara body is mounted which houses the sensor with the electronics and a lens mount. The rotating platform is driven by a belt connected to the geared stepper motor. The lens m42 lens mount allows for a large of range of lenses. Note with a different focal length the scan angle per line has to be different.
To capture the data from the linear sensor it is first digitized using an ADC/Timing generator also called an AFE. This device also is in charge of sending the timing signals to the CCD to move the charges and shift them towards the output. The AFE found on the V10/V100/V350 is an AK8419 from AKM. It has a publicly available datasheet which makes it easy to interface with.
To get the data of the AFE it uses a 8 bit parallel DDR data bus. For configuration it uses a serial interface. As the CCD has no public datasheet i captured the data being sent from the main board from the scanner to the sensor board.