TITLE "UART Controller"; 


%//////////////////
// INCLUDE FILES //
//////////////////%

INCLUDE "lpm_dff.inc";
INCLUDE "lpm_mux.inc";
INCLUDE "lpm_bustri.inc";


%////////////////////////////
// USER-DEFINED PARAMETERS //
////////////////////////////%

PARAMETERS
(
 FCLK,			-- Master Clock Frequency
CONFIG,			-- configration register content
BAUDRATE		-- Baudrate register content
);


%/////////////////////////
// CONSTANT DEFINITIONS //
/////////////////////////%

% DIVISOR VALUES %

CONSTANT DIV1200   = (FCLK+1200)   DIV (2*1200)   - 1;		-- 1200 Baud
CONSTANT DIV2400   = (FCLK+2400)   DIV (2*2400)   - 1;		-- 2400 Baud
CONSTANT DIV4800   = (FCLK+4800)   DIV (2*4800)   - 1;		-- 4800 Baud
CONSTANT DIV9600   = (FCLK+9600)   DIV (2*9600)   - 1;		-- 9600 Baud
CONSTANT DIV14400  = (FCLK+14400)  DIV (2*14400)  - 1;		-- 14400 Baud
CONSTANT DIV19200  = (FCLK+19200)  DIV (2*19200)  - 1;		-- 19200 Baud
CONSTANT DIV28800  = (FCLK+28800)  DIV (2*28800)  - 1;		-- 28800 Baud
CONSTANT DIV38400  = (FCLK+38400)  DIV (2*38400)  - 1;		-- 38400 Baud
CONSTANT DIV57600  = (FCLK+57600)  DIV (2*57600)  - 1;		-- 57600 Baud
CONSTANT DIV115200 = (FCLK+115200) DIV (2*115200) - 1;		-- 115200 Baud

%/////////////////////
// INPUTS & OUTPUTS //
/////////////////////%

SUBDESIGN UARTCTRL
(
 Di[7..0]										: INPUT;	-- Input Data Bus
 Do[7..0]										: OUTPUT;	-- Multiplexed Output Data Bus

 CLK, RESET, RD, WR, CS, A[1..0]				: INPUT;	-- CPU Interface
 INT, RCVD, SENT								: OUTPUT;
-- D[7..0]										: BIDIR;

 TxDIVISOR[16..0], TxCfgReg[6..0], TxReg[7..0]	: OUTPUT;	-- Tx Interface
 TxSTATUS, TxEnd 								: INPUT;	-- CTSf, DSRf					: INPUT;	
 TxStart, TxReset, TxCLK						: OUTPUT;

 RxSTATUS[4..0], RxReg[7..0]					: INPUT;	-- Rx Interface
 RxDIVISOR[16..0], RxCfgReg[6..0]				: OUTPUT;
 RxEnd 											: INPUT;	-- /RxRTS, /RxDTR							: INPUT;
 RxStart, RxReset, RxCLK						: OUTPUT;	-- , /RTS, /DTR			: OUTPUT;
)


%//////////////////////////
// VARIABLE DECLARATIONS //
//////////////////////////%

VARIABLE

% INTERNAL VARIABLES %
 --CfgReg[6..0]			: NODE;		-- UART Configuration Register
 --BaudReg[7..0]		: NODE;		-- UART Baud Rate Register (Write Only)
 DIVISOR[16..0]			: NODE;		-- Baud-Rate Clock Divisor
 DOMUX[7..0]			: NODE;		-- Output Data Bus Multiplexer
 DMXDo[3..0][7..0]		: NODE;		-- Demultiplexed Output Data Bus
 DIVd[16..0]			: NODE;		-- D-inputs to Divisor Register
 HANDSHAKE				: NODE;		-- Handshaking Type
BaudReg[7..0]			: NODE;
CfgReg[7..0]			: NODE;


% STATE MACHINES %
 RxRdss	: MACHINE WITH STATES (RxRd0, RxRd1, RxRd2);				-- Status Register Read
 TxWrss	: MACHINE WITH STATES (TxWr0, TxWr1, TxWr2);				-- Tx Register Write


%//////////////////
// LOGIC SECTION //
//////////////////%

BEGIN

% DEFAULT VALUES %
	CfgReg[7..0] = CONFIG;
	BaudReg[7..0] = BAUDRATE;

   IF    (BaudReg[] == 0) THEN DIVd[]=DIV1200;    --Ratess=Rate3;		-- Baud Rate = 1200
   ELSIF (BaudReg[] == 1) THEN DIVd[]=DIV2400;    --Ratess=Rate3;		-- Baud Rate = 2400
   ELSIF (BaudReg[] == 2) THEN DIVd[]=DIV4800;    --Ratess=Rate3;		-- Baud Rate = 4800
   ELSIF (BaudReg[] == 3) THEN DIVd[]=DIV9600;    --Ratess=Rate3;		-- Baud Rate = 9600
   ELSIF (BaudReg[] == 4) THEN DIVd[]=DIV14400;   --Ratess=Rate3;		-- Baud Rate = 14400
   ELSIF (BaudReg[] == 5) THEN DIVd[]=DIV19200;   --Ratess=Rate3;		-- Baud Rate = 19200
   ELSIF (BaudReg[] == 6) THEN DIVd[]=DIV28800;   --Ratess=Rate3;		-- Baud Rate = 28800
   ELSIF (BaudReg[] == 7) THEN DIVd[]=DIV38400;   --Ratess=Rate3;		-- Baud Rate = 38400
   ELSIF (BaudReg[] == 8) THEN DIVd[]=DIV57600;   --Ratess=Rate3;		-- Baud Rate = 57600
   ELSIF (BaudReg[] == 9) THEN DIVd[]=DIV115200;  --Ratess=Rate3;		-- Baud Rate = 115200
   ELSE DIVd[16..7]=0; DIVd[6..0]=BaudReg[6..0];  --Ratess=Rate3;		-- Baud Rate = FCLK/(2*BaudReg[6..0] + 2)
   END IF;

  TxREG[]	= LPM_DFF (Di[7..0], WR # CS # A1 # A0, VCC,,,,,, RESET,,)	-- Tx Data Register
              WITH (LPM_WIDTH=8)
              RETURNS (.q[]);
  DIVISOR[] = DIVd[];
 DOMUX[]	= LPM_MUX (.Data[][] = DMXDo[3..0][7..0], .Sel[] = A[1..0])						-- Output Data Bus Multiplexer
              WITH (LPM_WIDTH=8, LPM_SIZE=4, LPM_WIDTHS=2)
              RETURNS (.result[]);
 RCVD		= LPM_DFF (RxEND, CLK,,,,,,, RESET,,)							-- Rx Interrupt
              WITH (LPM_WIDTH=1)
              RETURNS (.q[]);
 SENT		= LPM_DFF (TxEND, CLK,,,,,,, RESET,,)							-- Tx Interrupt
              WITH (LPM_WIDTH=1)
              RETURNS (.q[]);
 INT		= LPM_DFF (RxEND # TxEND, CLK,,,,,,, RESET,,)					-- Rx/Tx Common Interrupt
              WITH (LPM_WIDTH=1)
              RETURNS (.q[]);

% COMBINATORIAL LOGIC %
 RxDIVISOR[]=DIVISOR[];		-- Common Rx/Tx Inputs
 TxDIVISOR[]=DIVISOR[];
 RxCfgReg[]=CfgReg[6..0];
 TxCfgReg[]=CfgReg[6..0];
 RxCLK=CLK;
 TxCLK=CLK;

 HANDSHAKE=CfgReg[6];

  

 Do[]=DOMUX[];				-- Multiplexed Output Data Bus
 DMXDo[0][]=RxREG[];		-- Demultiplexed Output Data Bus
 DMXDo[1][0]=TxSTATUS;
 DMXDo[1][5..1]=RxSTATUS[];
 DMXDo[1][7..6]=0;
 DMXDo[2][]=0;
 DMXDo[3][0]=GND;--CTSf;
 DMXDo[3][1]=GND;--DSRf;
 DMXDo[3][7..2]=0;

 RxReset=RESET;				-- Rx Reset
 TxReset=RESET;				-- Tx Reset

% STATE MACHINES %
 RxRdss.CLK = CLK;
 RxRdss.RESET= RESET;
 TxWrss.CLK = CLK;
 TxWrss.RESET= RESET;

% Rx DATA REGISTER READ STATE MACHINE %
 CASE RxRdss	IS

  WHEN RxRd0 =>		-- Wait for a Read from the Rx Data Register
   IF !(CS # A0 # A1 # Rd # !WR) THEN RxRdss=RxRd1; 
   ELSE RxRdss=RxRd0;
   END IF;

  WHEN RxRd1 =>		-- Wait until Rx Data Register Read is completed
   IF (CS # A0 # A1 # Rd # !WR) THEN RxRdss=RxRd2; 
   ELSE RxRdss=RxRd1;
   END IF;

  WHEN RxRd2 =>		-- Clear Rx Status Register
   RxStart=VCC;
   RxRdss=RxRd0; 

 END CASE;


% Tx DATA REGISTER WRITE STATE MACHINE %
 CASE TxWrss	IS

  WHEN TxWr0 =>		-- Wait for a Write to the Tx Data Register
   IF !(CS # A0 # A1 # !Rd # WR) THEN TxWrss=TxWr1; 
   ELSE TxWrss=TxWr0;
   END IF;

  WHEN TxWr1 =>		-- Wait until Tx Data Register Write is completed
   IF (CS # A0 # A1 # !Rd # WR) THEN TxWrss=TxWr2; 
   ELSE TxWrss=TxWr1;
   END IF;

  WHEN TxWr2 =>		-- Enable Tx
   TxStart=VCC;
   TxWrss=TxWr0;

 END CASE;

END;