UART-SPI-BRIDGE-VHDL

• COMMAND BYTE SEND 8 BIT DATA "MAALLLL":

     where M is Mode              : 0 for Write Mode, 1 for Read Mode
  
     AA  is Address         : 00 -> Slave 0, 01 -> Slave 1, 10 -> Slave 2, 11 -> Slave 3
     
     LLLL is Length of Data : 01000 for 8 bit and 10000 for 16 bit transfer
  

• DATA BYTE

Write Mode :

if 8 bit send the data byte  CLKS_PER_BIT*12 time after command byte is sent

if 16 bit send the data byte CLKS_PER_BIT*12 time after command byte is sent and next byte (CLKS_PER_BIT*12) time after 1st byte

Read Mode :

if 8 bit  wait after   sending command byte

if 16 bit send command byte again after recieving 1st byte from SPI to get 2nd byte

Eg:

to write 8 bit data to slave 0

command byte will be :- 00001000

and then the data byte

to write 16 bit data to slave 1

command byte will be :- 00110000

and then the data bytes 

to read 8 bit data to slave 2

command byte will be :- 11001000

to read 16 bit data to slave 3

command byte will be :- 11110000

• SIMULATION RESULTS