kikic -3 Light Poster

I have to write for the program. If someone could help me to understand the problem?? The example of the MAC message would be very useful for me

program the PIC to work as a Super Router, and reading the serial port frame, forwards them to the standard, or rejected. The next message format:`enter code here'
---First Destination MAC, 6 bytes fixed - variable value for each frame
---Second TTL, 1 byte fixed - variable value for each frame
---Third Length, 1 byte fixed - variable value for each frame
---4th Data, [1, 16] bytes - variable value, variable length for each frame
---5th Error Code, 1 byte fixed - sum of all units in the field 1-4

And process the PIC as follows:
First Checking the MAC address. - If it is rejected and the LCD display reads in two lines - "Received message is not for me ". - If it is addressed, go to step 2 Second Checking the Error Code. - If the frame is error, rejecting the LCD screen and write in two rows - "Received frame is wrong". - If the frame is not an error, go to step 3 Third Check the TTL. - If the TTL = 0, the frame is discarded and the LCD display reads in two rows - "Receive frame with TTL = 0". - If TTL> 0, go to step 4. 4th Creating a framework for sending. - In the Dest. MAC value is entered as DestMac own arbitrary will create it as a variable - TTL field is reduced by 1 from the received frame - Length field remains the same - Data remains the same field - Calculate new value for the Error Code field After creating the frame, it sends the serial port, and write the first row of the LCD - "Send frame:", second row area Data After sending, wait for a new framework. Assume that in the meantime not to arrive new framework.