1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
|
//
// Copyright 2012 Ettus Research LLC
//
// This program is free software: you can redistribute it and/or modify
// it under the terms of the GNU General Public License as published by
// the Free Software Foundation, either version 3 of the License, or
// (at your option) any later version.
//
// This program is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
// GNU General Public License for more details.
//
// You should have received a copy of the GNU General Public License
// along with this program. If not, see <http://www.gnu.org/licenses/>.
//
// Simple I2C core
// Settings reg map:
//
// BASE+0 control register
// byte0 - control bits, data byte, or command bits, prescaler
// byte1 - what to do? (documented in cpp file)
// write prescaler lo
// write prescaler hi
// write control
// write data
// write command
// read data
// read status
//
// Readback:
//
// byte0 has readback value based on the last read command
//
module simple_i2c_core
#(
//settings register base address
parameter BASE = 0,
//i2c line level at reset
parameter ARST_LVL = 1
)
(
//clock and synchronous reset
input clock, input reset,
//32-bit settings bus inputs
input set_stb, input [7:0] set_addr, input [31:0] set_data,
//32-bit data readback
output reg [31:0] readback,
//read is high when i2c core can begin another transaction
output reg ready,
// I2C signals
// i2c clock line
input scl_pad_i, // SCL-line input
output scl_pad_o, // SCL-line output (always 1'b0)
output scl_padoen_o, // SCL-line output enable (active low)
// i2c data line
input sda_pad_i, // SDA-line input
output sda_pad_o, // SDA-line output (always 1'b0)
output sda_padoen_o, // SDA-line output enable (active low)
//optional debug output
output [31:0] debug
);
//declare command settings register
wire [7:0] sr_what, sr_data;
wire sr_changed;
setting_reg #(.my_addr(BASE+0),.width(16)) i2c_cmd_sr(
.clk(clock),.rst(reset),.strobe(set_stb),.addr(set_addr),.in(set_data),
.out({sr_what, sr_data}),.changed(sr_changed));
//declare wb interface signals
wire [2:0] wb_addr;
wire [7:0] wb_data_mosi;
wire [7:0] wb_data_miso;
wire wb_we, wb_stb, wb_cyc;
wire wb_ack;
//create wishbone-based i2c core
i2c_master_top #(.ARST_LVL(ARST_LVL)) i2c
(.wb_clk_i(clock),.wb_rst_i(reset),.arst_i(1'b0),
.wb_adr_i(wb_addr),.wb_dat_i(wb_data_mosi),.wb_dat_o(wb_data_miso),
.wb_we_i(wb_we),.wb_stb_i(wb_stb),.wb_cyc_i(wb_cyc),
.wb_ack_o(wb_ack),.wb_inta_o(),
.scl_pad_i(scl_pad_i),.scl_pad_o(scl_pad_o),.scl_padoen_o(scl_padoen_o),
.sda_pad_i(sda_pad_i),.sda_pad_o(sda_pad_o),.sda_padoen_o(sda_padoen_o) );
//not ready between setting register and wishbone ack
always @(posedge clock) begin
if (reset || wb_ack) ready <= 1;
else if (sr_changed) ready <= 0;
end
//register wishbone data on every ack
always @(posedge clock) begin
if (wb_ack) readback <= {24'b0, wb_data_miso};
end
//assign wishbone signals
assign wb_addr = sr_what[2:0];
assign wb_stb = sr_changed;
assign wb_we = wb_stb && sr_what[3];
assign wb_cyc = wb_stb;
assign wb_data_mosi = sr_data;
endmodule //simple_i2c_core
|
