Black Spot Hardware
The Black Spot is a small camera module containing a processing unit, an image sensor, and a lens assembly. photograph of this module is shown in Figure 5.1. In the pho- tograph, the lens assembly is the white cylindrical mount and the large black chip is the processing unit (Blackfin DSP). This unit runs the software described in Chapter 4. Mod- ules can be connected together using a shared bus and transmit data to the hub (Figure 5.2).
This chapter describes the hardware and the decisions that were made during design and development. Initially a number of different designs were considered and an overview of these are given in Section 5.1. The devices chosen for the design are discussed in Section 5.2 followed by design considerations (Section 5.3), a design overview (Section 5.4), and finally the production of these modules (Section 5.5).
number of designs were initially investigated before choosing a design based around a Blackfin DSP and a CMOS image sensor. The base design is shown in Figure 5.3. This shows an image sensor attached to a device marked X. This device provides the clock signal to the image sensor, sends and receives configuration data, and receives image data. Field Programmable Gate rrays (FPG ), general purpose microprocessors, and DSPs were con- sidered for this device. The advantages and disadvantages of each device are described in the following subsections.
Image sensor and FPG
with RISC soft core
One approach for the camera module would have been to combine a CMOS image sensor and a FPG with a soft core processor. FPG s contain many programmable logic elements
that can implement
ND, OR, and NOT gates . These logic elements can be combined