You are required to design and document  the hardware design  for a 68HC12D60 based Lift Control Unit (LCU). This design includes  the Input/Output hardware for interfacing with  lift equipment, display, external memory and bus circuitry as described in questions below.

1.  Block Diagram

Draw a block diagram showing all the hardware components of the lift and the proposed lift control unit (including the I/O ports of the HC12), clearly showing the connection of signals between them.

2.  Microprocessor support

Draw a circuit diagram showing the minimum components needed to correctly operate the HC12  D60 microprocessor in normal expanded narrow mode.  (That is  -  for  external memory using an 8 bit data bus) You should ensure that:

(a)  power is provided to the HC12 (assume a regulated 5V supply is available)

(b)  interrupts are in their inactive condition

(c)  the microprocessor E clock operates at 8MHz

(d)  a reset circuit is provided.

(e)  data and address buffers/latches are used as required.

You must specify part numbers and suggest values for any components used.

3.  Memory Decoding

You must determine the amount of RAM required to meet the data storage requirements of the system for a 6 month operation of the lift. (Report your calculations for this as part of this question) Draw a circuit diagram  for  the  address decoding  hardware  required  to decode external memory  attached to  the HC12D60 microcontroller,  to match  the memory map  of figure 1. You must show how the E clock signal from a HC12 is used in the circuit to enable the decoders at the correct time in the microprocessor cycle. Clearly identify all ICs used, label all pins on all parts and label the signals coming to and from the parts.