2. Two 16F873A microcontrollers are to be connected together with a synchronous serial link, operating in SPI (Serial Peripheral Interface) mode. One is to act as Master, the other as Slave. No other nodes are required. Data needs to be sent in both directions. A serial bit rate of 2MHz is required. Each microcontroller is running with an 8 MHz crystal oscillator. (a) (i) Draw a simple block diagram, showing the two microcontrollers and indicating how the serial connection is made. Clearly label the pins being used. Show on your diagram which is Master and which Slave. You need show only the connections necessary for the serial link; no other connections need be shown. (ii) For each microcontroller, indicate how SSPCON1 should be configured. Con- sider only bits 0 to 5, and use X to show dont care for bits which have no impact on this particular requirement. (iii) Briefly explain each selection made. (b) Explain briefly the disadvantages of a simple serial protocol like this, for example in situations where multiple nodes and high reliability are required.