IOP16 Timer Unit

Timer Unit

• Operates as a One-shot counter with single value
• Count uS, mSec or secs (allows for different resolutions)
• Write to count value starts timer
• Poll timer status

Address Value      Read/Write Data
0       uSec Count Write      0-255 uS count - write starts timer
1       mSec Count Write      0-255 mS count - write starts timer 
2       Sec Count  Write      0-255 sec count - write starts timer
3       Not Used   Write      Not used
0-3     Status     Read       1 = Count In progresss
                              0 = Done

Timer Unit Subroutines

• Wait for 1 second

START	IOW	0X08	0X00	WRITE TO LED
	LRI	0X00	0X01	TIME 1 SEC
	IOW	0X00	0X06	STORE TO START TIMER
WAITDUN	IOR	0X01	0X04	READ TIMER
	ARI	0X01	0X01	CHECK BUSY
	BNZ	WAITDUN		

Entity

-- ____________________________________________________________________________________
-- Timer Unit
w_timerAdr	<=	'1' when (w_peripAddr(7 downto 2) = "000010") else '0';
timerUnit : entity work.TimerUnit
  port map
  (
    -- Clock and Reset
    i_clk         => i_clock,
    i_n_reset     => w_resetClean_n,
    -- The key and LED on the FPGA card 
    i_timerSel    => w_timerAdr,
    i_writeStrobe => w_peripWr,
    i_regSel      => w_peripAddr(1 downto 0),
    i_dataIn      => w_peripDataFromCPU,
    o_dataOut    => w_timerOut
);

Resources (EP4CE15)

• Logic Cells: 89
• Registers: 49
• Memory Bits: 0