Help with external component in SOPC builder

Altera_Forum · ‎04-08-2005

Hi. We have to communicate with an external chip form Nios II. We have built an expansion card that we have put on the proto 2 connector. The external chip is a Phillips PDIUSBD12. We have written a driver for it in eCos and we have problems getting it to work. After some debugging it looks like there's something wrong with the i/o pins. We get a 7.3 MHz signal as noise on one of the i/o's, on a couple of others it looks like the signal is inverted and phaseshifted.

We made a verilog-file to describe the i/o's on the PDIUSBD12. I do not know verilog, so I just looked at the verilog code for the Compact Flash component that is on this forum. I just thought I'd connect the signals to the proper avalon signals, and it would work. I can connect to the chip and make it work for a little time, but then it's unstable. This is my verilog code:

module pdiusbd12 (
    usb_avalon_data_in, usb_avalon_data_out, usb_avalon_address, usb_avalon_cs_n, usb_avalon_read_n, usb_avalon_write_n,
    usb_avalon_interrupt, usb_avalon_reset_n, usb_avalon_clk,
    usb_data, usb_address, usb_cs_n, usb_read_n, usb_write_n, usb_interrupt, usb_reset_n
);
input  usb_avalon_data_in;
output  usb_avalon_data_out;
input usb_avalon_reset_n;
input usb_avalon_address;
input usb_avalon_cs_n;
input usb_avalon_read_n;
input usb_avalon_write_n;
output usb_avalon_interrupt;
input usb_avalon_clk;
inout  usb_data;
output usb_address;
output usb_cs_n;
output usb_read_n;
output usb_write_n;
input usb_interrupt;
output usb_reset_n;
assign usb_read_n = usb_avalon_read_n;
assign usb_write_n = usb_avalon_write_n;
assign usb_cs_n = usb_avalon_cs_n;
assign usb_avalon_interrupt = usb_interrupt;
// Generate bi-directional data lines
assign usb_avalon_data_out = (usb_avalon_read_n == 1&#39;b0) ? usb_data : 8&#39;hFF;
assign usb_data = (usb_avalon_write_n == 1&#39;b0) ? usb_avalon_data_in : 8&#39;hZZ;
assign usb_address = usb_avalon_address;
// Reset the card when this avalon component is reset.
assign usb_reset_n = usb_avalon_reset_n;
endmodule

Do you see anything criticallly wrong? The documentation says that I should just make a new component in SOPC and just make the signals there. But how do I then control stuff like irq, write_n and such? I can't find any way to connect the interrupt to the avalon interrupt by hand. With the above code, I think it's done. And how do I set the timings right? The PDIUSBD12 need 600 ns to register that the cs_n and wr_n has gone low and to take in the data. I just looked at the Compact Flash component and did something similar to what was done there.

Ole