components base address and offsets

If you are talking about the macros like IORD_32DIRECT, offset is just how many bytes from the base address.

For example if you have a component which has two 32bit registers, you might have something like this:

BASE = 0x1000 //some base address

LENGTH = 2 //2 registers

Then to read the first register you would have

IORD_32DIRECT(BASE, 0); //first register is at BASE+0 bytes

To read the second register you would have:

IORD_32DIRECT(BASE,4); //second register is at BASE+4 bytes (aka BASE+32bit)

If you were trying to access fourth byte of the first register you would do:

IORD_8DIRECT(BASE,3); //fourth byte of first register is 3 bytes after the base address.

OK I did not get it, here is my components slave interface :

port ( clk : in std_logic;

resetn : in std_logic;

read : in std_logic;

write : in std_logic;

chipselect : in std_logic;

writedata : in std_logic_vector(15 downto 0);

byteenable : in std_logic_vector(1 downto 0);

address : in std_logic_vector(1 downto 0);

readdata : out std_logic_vector(15 downto 0);

SIG_EXT : out std_logic_vector(1 downto 0)

);

How do I write some data to the ""writedata"" pin ???

IOWR_16DIRECT(BASE_ADDRESS, 2*(address),DATA); //write 16bits of 'DATA' to the component at 'BASE_ADDRESS' plus offset.

Data is 16bit so addresses on your 'address' bus are spaced 2bytes apart, hence multiply by 2 when passing to the write macro. The base address can be found in the "system.h" file in the Nios BSP.

what do you mean by (address), is it the "2 bits pin" ??

if that's the case, well, I am not using it in my system (architecture) !

I just added to the entity to avoid any errors when "Qsys" generates the system.

A memory mapped interface has an address bus, and one or two data buses (read and/or write).

Your component has a 2bit port called 'Address' which I presume is the address line for your Avalon-MM slave.

If you are not using the address line, just assume address is 0, so offset will always be 0.

Whenever I build my project in Nios II IDE I get this error :

make: Interrupt/Exception caught (code = 0xc0000005, addr = 0x403a39)

how can I fix that ?