The MC68332 Embedded Controller provides a new level of control and processing capability by providing a distributed processing environment on a single silicon device. The MC68332 is more than a bigger CPU with more complex peripherals tied to its internal busses. The MC68332 is actually three separate computer systems integrated into a single unit.
The CPU32, of course, is the heart of the computing power. It is based on the widely used MC68020 microprocessor and is object code compatible with the MC68020. The second element of the MC68332 is the Time Processing Unit (TPU). It encompasses an internal ALU with its own microcode. The TPU performs functions at the direction of the CPU32. The CPU32 cannot directly operate the timer channels. It must do so indirectly by passing control words and parameters through a shared set of registers and RAM. The Queued Serial Module (QSM) operates in much the same manner as the TPU.
The QSM consists of a Serial Communications Interface which functions as a basic Universal Asynchronous Receiver-transmitter (UART) and a Serial Peripheral Interface (SPI) which communicates synchronously with other devices. The QSM has its own microengine and microcode and processes jobs at the direction of the CPU32. Once again. the CPU32 cannot directly control the actual serial port hardware. This must be done by passing commands and parameters through shared registers and RAM. The MC68332 performs one other very important function. A significant amount of the interface logic used to connect to external memory and peripherals is included within the chip. For instance. up to 11 chip select signals can be generated. Data Strobe Acknowledge and Address Strobe Acknowledge circuits as well as programmable memory wait state generators are also incorporated. The entire philosophy of the MC68332 includes the ideas of integrating as much of the overall system electronics onto one chip as possible.