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

• Pass number of secs to wait in Reg1

WAITSECS	IOW	0X01		0X06	STORE REG0 TO START TIMER
WTLPSEC		IOR	0X01		0X04	READ TIMER
		ARI	0X01		0X01	CHECK BUSY
		BNZ	WTLPSEC		
		RTS			

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