OpenRisc入门（19） or1200下linux的i2c(一)

这篇blog介绍I2C的学习了，首先要在我们的or1200_soc上添加进来I2C Controller，到opencores社区上面找到i2c_latest.tar.gz这个工程包。

解压得到如下文件目录：

注意啦，这里的i2c_top.v的顶层文件需要自己编写，因为需要在工程的更顶层将i2c_master_top.v里的输入输出信号组织成三态信号。

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1. module i2c_top(
2. //wishbone interfaces
3. wb_clk_i, wb_rst_i, arst_i,
4. wb_adr_i, wb_dat_i, wb_dat_o,
5. wb_we_i, wb_stb_i, wb_cyc_i, wb_ack_o, wb_inta_o,
6. i2c_scl, i2c_sda
7. );
8. // wishbone signals
9. input wb_clk_i; // master clock input
10. input wb_rst_i; // synchronous active high reset
11. input arst_i; // asynchronous reset
12. input [2:0] wb_adr_i; // lower address bits
13. input [7:0] wb_dat_i; // databus input
14. output [7:0] wb_dat_o; // databus output
15. input wb_we_i; // write enable input
16. input wb_stb_i; // stobe/core select signal
17. input wb_cyc_i; // valid bus cycle input
18. output wb_ack_o; // bus cycle acknowledge output
19. output wb_inta_o; // interrupt request signal output
20. // i2c signals
21. inout i2c_scl; //i2c clock signal
22. inout i2c_sda; //i2c data signal
23. i2c_master_top i2c_master_top(
24. //wishbone interfaces
25. .wb_clk_i(wb_clk_i),
26. .wb_rst_i(wb_rst_i),
27. .arst_i(arst_i),
28. .wb_adr_i(wb_adr_i),
29. .wb_dat_i(wb_dat_i),
30. .wb_dat_o(wb_dat_o),
31. .wb_we_i(wb_we_i),
32. .wb_stb_i(wb_stb_i),
33. .wb_cyc_i(wb_cyc_i),
34. .wb_ack_o(wb_ack_o),
35. .wb_inta_o(wb_inta_o),
36. .scl_pad_i(scl_pad_i),
37. .scl_pad_o(scl_pad_o),
38. .scl_padoen_o(scl_padoen_o),
39. .sda_pad_i(sda_pad_i),
40. .sda_pad_o(sda_pad_o),
41. .sda_padoen_o(sda_padoen_o)
42. );
43.  
44. assign i2c_scl = scl_padoen_o 1'bz : scl_pad_o;
45. assign i2c_sda = sda_padoen_o 1'bz : sda_pad_o;
46. assign scl_pad_i = i2c_scl;
47. assign sda_pad_i = i2c_sda;
48. endmodule