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//============================================================================
// ZX Spectrum keyboard input
//
// This module takes scan-codes from the attached PS/2 keyboard and sets
// corresponding ZX key bitfields which are read by the 'IN' instructions.
//
// PS/2      |  ZX Spectrum
// ----------+-----------------
// CTRL      |  CAPS SHIFT
// ALT       |  SYMBOL SHIFT
//
// For convenience, in addition to regular alpha-numeric keys, this code
// simulates several other standard symbols on the PS/2 keyboard.
//
// PS/2      |  ZX Spectrum
// ----------+-----------------
// BACKSPACE |  DELETE
// Arrows Left, Right, Up, Down
// ESC       |  BREAK (CAPS+SPACE)
// SHIFT => PS/2 shift for additional keys: -_ += ;: "' <, >. ?/
//
//  Copyright (C) 2014-2016  Goran Devic
//
//  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 2 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, write to the Free Software Foundation, Inc.,
//  51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
//============================================================================
module zx_keyboard
(
    input wire clk,
    input wire nreset,          // Active low reset
 
    // Output ZX-specific keyboard codes when requested by the ULA access
    input wire [15:0] A,        // Address bus
    output wire [4:0] key_row,  // Output the state of a requested row of keys
 
    // Input key scan codes from the PS/2 keyboard
    input wire [7:0] scan_code, // PS/2 scan-code
    input wire scan_code_ready, // Active for 1 clock: a scan code is ready
    input wire scan_code_error, // Error receiving PS/2 keyboard data
    output wire pressed         // Signal that a key is pressed
);
 
//~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
//
//~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
reg [4:0] keys [0:7];       // 8 rows of 5 bits each: contains 0 for a pressed key at a specific location, 1 otherwise
 
reg released;               // Tracks "released" scan code (F0): contains 0 when a key is pressed, 1 otherwise
reg extended;               // Tracks "extended" scan code (E0)
reg shifted;                // Tracks local "shifted" state
 
// Calculate a "key is pressed" signal
assign pressed = ~(&keys[7] & &keys[6] & &keys[5] & &keys[4] & &keys[3] & &keys[2] & &keys[1] & &keys[0]);
 
// Output requested row of keys continously
assign key_row =
    (~A[8]  ? keys[0] : 5'b11111) &
    (~A[9]  ? keys[1] : 5'b11111) &
    (~A[10] ? keys[2] : 5'b11111) &
    (~A[11] ? keys[3] : 5'b11111) &
    (~A[12] ? keys[4] : 5'b11111) &
    (~A[13] ? keys[5] : 5'b11111) &
    (~A[14] ? keys[6] : 5'b11111) &
    (~A[15] ? keys[7] : 5'b11111);
 
always @(posedge clk or negedge nreset)
begin
    if (!nreset) begin
        released <= 0;
        extended <= 0;
        shifted  <= 0;
 
        keys[0] <= '1;
        keys[1] <= '1;
        keys[2] <= '1;
        keys[3] <= '1;
        keys[4] <= '1;
        keys[5] <= '1;
        keys[6] <= '1;
        keys[7] <= '1;
    end else
    if (scan_code_ready) begin
        if (scan_code==8'hE0) // Extended code prefix byte
            extended <= 1;
        else if (scan_code==8'hF0) // Break code prefix byte
            released <= 1;
        else begin
            // Cancel release/extended flags for the next clock
            extended <= 0;
            released <= 0;
 
            if (extended) begin
                // Extended keys
                case (scan_code)
                    8'h6B:  begin                       // LEFT
                            keys[0][0] <= released;     // CAPS SHIFT
                            keys[3][4] <= released;     // 5
                            end
                    8'h72:  begin                       // DOWN
                            keys[0][0] <= released;     // CAPS SHIFT
                            keys[4][4] <= released;     // 6
                            end
                    8'h75:  begin                       // UP
                            keys[0][0] <= released;     // CAPS SHIFT
                            keys[4][3] <= released;     // 7
                            end
                    8'h74:  begin                       // RIGHT
                            keys[0][0] <= released;     // CAPS SHIFT
                            keys[4][2] <= released;     // 8
                            end
                endcase
            end
            else begin
                // For each PS/2 scan-code, set the ZX keyboard matrix state
                case (scan_code)
                    8'h12:  shifted <= !released;       // Local SHIFT key (left)
                    8'h59:  shifted <= !released;       // Local SHIFT key (right)
 
                    8'h14:  keys[0][0] <= released;     // CAPS SHIFT = Left or right Ctrl
 
                    8'h1A:  keys[0][1] <= released;     // Z
                    8'h22:  keys[0][2] <= released;     // X
                    8'h21:  keys[0][3] <= released;     // C
                    8'h2A:  keys[0][4] <= released;     // V
 
                    8'h1C:  keys[1][0] <= released;     // A
                    8'h1B:  keys[1][1] <= released;     // S
                    8'h23:  keys[1][2] <= released;     // D
                    8'h2B:  keys[1][3] <= released;     // F
                    8'h34:  keys[1][4] <= released;     // G
 
                    8'h15:  keys[2][0] <= released;     // Q
                    8'h1D:  keys[2][1] <= released;     // W
                    8'h24:  keys[2][2] <= released;     // E
                    8'h2D:  keys[2][3] <= released;     // R
                    8'h2C:  keys[2][4] <= released;     // T
 
                    8'h16:  keys[3][0] <= released;     // 1
                    8'h1E:  keys[3][1] <= released;     // 2
                    8'h26:  keys[3][2] <= released;     // 3
                    8'h25:  keys[3][3] <= released;     // 4
                    8'h2E:  keys[3][4] <= released;     // 5
 
                    8'h45:  keys[4][0] <= released;     // 0
                    8'h46:  keys[4][1] <= released;     // 9
                    8'h3E:  keys[4][2] <= released;     // 8
                    8'h3D:  keys[4][3] <= released;     // 7
                    8'h36:  keys[4][4] <= released;     // 6
 
                    8'h4D:  keys[5][0] <= released;     // P
                    8'h44:  keys[5][1] <= released;     // O
                    8'h43:  keys[5][2] <= released;     // I
                    8'h3C:  keys[5][3] <= released;     // U
                    8'h35:  keys[5][4] <= released;     // Y
 
                    8'h5A:  keys[6][0] <= released;     // ENTER
                    8'h4B:  keys[6][1] <= released;     // L
                    8'h42:  keys[6][2] <= released;     // K
                    8'h3B:  keys[6][3] <= released;     // J
                    8'h33:  keys[6][4] <= released;     // H
 
                    8'h29:  keys[7][0] <= released;     // SPACE
                    8'h11:  keys[7][1] <= released;     // SYMBOL SHIFT (Red) = Left and right Alt
                    8'h3A:  keys[7][2] <= released;     // M
                    8'h31:  keys[7][3] <= released;     // N
                    8'h32:  keys[7][4] <= released;     // B
 
                    8'h66:  begin                       // BACKSPACE
                            keys[0][0] <= released;
                            keys[4][0] <= released;
                            end
                    8'h76:  begin                       // ESC -> BREAK
                            keys[0][0] <= released;     // CAPS SHIFT
                            keys[7][0] <= released;     // SPACE
                            end
                    // With shifted keys, we need to make inactive (set to 1) other corresponding key
                    // Otherwise, it will stay active if the shift was released first
                    8'h4E:  begin                       // - or (shifted) _
                            keys[7][1] <= released;     // SYMBOL SHIFT (Red)
                            keys[4][0] <= shifted ? released : 1;     // 0
                            keys[6][3] <= shifted ? 1 : released;     // J
                            end
                    8'h55:  begin                       // = or (shifted) +
                            keys[7][1] <= released;     // SYMBOL SHIFT (Red)
                            keys[6][2] <= shifted ? released : 1;     // K
                            keys[6][1] <= shifted ? 1 : released;     // L
                            end
                    8'h52:  begin                       // ' or (shifted) "
                            keys[7][1] <= released;     // SYMBOL SHIFT (Red)
                            keys[5][0] <= shifted ? released : 1;     // P
                            keys[4][3] <= shifted ? 1 : released;     // 7
                            end
                    8'h4C:  begin                       // ; or (shifted) :
                            keys[7][1] <= released;     // SYMBOL SHIFT (Red)
                            keys[0][1] <= shifted ? released : 1;     // Z
                            keys[5][1] <= shifted ? 1 : released;     // O
                            end
                    8'h41:  begin                       // , or (shifted) <
                            keys[7][1] <= released;     // SYMBOL SHIFT (Red)
                            keys[2][3] <= shifted ? released : 1;     // R
                            keys[7][3] <= shifted ? 1 : released;     // N
                            end
                    8'h49:  begin                       // . or (shifted) >
                            keys[7][1] <= released;     // SYMBOL SHIFT (Red)
                            keys[2][4] <= shifted ? released : 1;     // T
                            keys[7][2] <= shifted ? 1 : released;     // M
                            end
                    8'h4A:  begin                       // / or (shifted) ?
                            keys[7][1] <= released;     // SYMBOL SHIFT (Red)
                            keys[0][3] <= shifted ? released : 1;     // C
                            keys[0][4] <= shifted ? 1 : released;     // V
                            end
                endcase
            end
        end
    end
end
 
endmodule

Line No.	Rev	Author	Line
1	8	gdevic	`//============================================================================`
2	10	gdevic	`// ZX Spectrum keyboard input`
3	8	gdevic	`//`
4	10	gdevic	`// This module takes scan-codes from the attached PS/2 keyboard and sets`
5			`// corresponding ZX key bitfields which are read by the 'IN' instructions.`
6			`//`
7	8	gdevic	`// PS/2 \| ZX Spectrum`
8			`// ----------+-----------------`
9			`// CTRL \| CAPS SHIFT`
10			`// ALT \| SYMBOL SHIFT`
11			`//`
12	10	gdevic	`// For convenience, in addition to regular alpha-numeric keys, this code`
13			`// simulates several other standard symbols on the PS/2 keyboard.`
14	8	gdevic	`//`
15			`// PS/2 \| ZX Spectrum`
16			`// ----------+-----------------`
17			`// BACKSPACE \| DELETE`
18			`// Arrows Left, Right, Up, Down`
19			`// ESC \| BREAK (CAPS+SPACE)`
20	10	gdevic	`// SHIFT => PS/2 shift for additional keys: -_ += ;: "' <, >. ?/`
21	8	gdevic	`//`
22			`// Copyright (C) 2014-2016 Goran Devic`
23			`//`
24			`// This program is free software; you can redistribute it and/or modify it`
25			`// under the terms of the GNU General Public License as published by the Free`
26			`// Software Foundation; either version 2 of the License, or (at your option)`
27			`// any later version.`
28			`//`
29			`// This program is distributed in the hope that it will be useful, but WITHOUT`
30			`// ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or`
31			`// FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for`
32			`// more details.`
33			`//`
34			`// You should have received a copy of the GNU General Public License along`
35			`// with this program; if not, write to the Free Software Foundation, Inc.,`
36			`// 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.`
37			`//============================================================================`
38			`module zx_keyboard`
39			`(`
40			`input wire clk,`
41	10	gdevic	`input wire nreset, // Active low reset`
42	8	gdevic
43			`// Output ZX-specific keyboard codes when requested by the ULA access`
44			`input wire [15:0] A, // Address bus`
45			`output wire [4:0] key_row, // Output the state of a requested row of keys`
46
47			`// Input key scan codes from the PS/2 keyboard`
48			`input wire [7:0] scan_code, // PS/2 scan-code`
49			`input wire scan_code_ready, // Active for 1 clock: a scan code is ready`
50			`input wire scan_code_error, // Error receiving PS/2 keyboard data`
51			`output wire pressed // Signal that a key is pressed`
52			`);`
53
54			`//~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~`
55			`//`
56			`//~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~`
57	13	gdevic	`reg [4:0] keys [0:7]; // 8 rows of 5 bits each: contains 0 for a pressed key at a specific location, 1 otherwise`
58	8	gdevic
59	13	gdevic	`reg released; // Tracks "released" scan code (F0): contains 0 when a key is pressed, 1 otherwise`
60	8	gdevic	`reg extended; // Tracks "extended" scan code (E0)`
61			`reg shifted; // Tracks local "shifted" state`
62
63			`// Calculate a "key is pressed" signal`
64			`assign pressed = ~(&keys[7] & &keys[6] & &keys[5] & &keys[4] & &keys[3] & &keys[2] & &keys[1] & &keys[0]);`
65
66			`// Output requested row of keys continously`
67	10	gdevic	`assign key_row =`
68			`(~A[8] ? keys[0] : 5'b11111) &`
69			`(~A[9] ? keys[1] : 5'b11111) &`
70			`(~A[10] ? keys[2] : 5'b11111) &`
71			`(~A[11] ? keys[3] : 5'b11111) &`
72			`(~A[12] ? keys[4] : 5'b11111) &`
73			`(~A[13] ? keys[5] : 5'b11111) &`
74			`(~A[14] ? keys[6] : 5'b11111) &`
75			`(~A[15] ? keys[7] : 5'b11111);`
76	8	gdevic
77	10	gdevic	`always @(posedge clk or negedge nreset)`
78	8	gdevic	`begin`
79	10	gdevic	`if (!nreset) begin`
80	8	gdevic	`released <= 0;`
81			`extended <= 0;`
82			`shifted <= 0;`
83
84			`keys[0] <= '1;`
85			`keys[1] <= '1;`
86			`keys[2] <= '1;`
87			`keys[3] <= '1;`
88			`keys[4] <= '1;`
89			`keys[5] <= '1;`
90			`keys[6] <= '1;`
91			`keys[7] <= '1;`
92			`end else`
93			`if (scan_code_ready) begin`
94	13	gdevic	`if (scan_code==8'hE0) // Extended code prefix byte`
95	8	gdevic	`extended <= 1;`
96	13	gdevic	`else if (scan_code==8'hF0) // Break code prefix byte`
97	8	gdevic	`released <= 1;`
98			`else begin`
99			`// Cancel release/extended flags for the next clock`
100			`extended <= 0;`
101			`released <= 0;`
102
103			`if (extended) begin`
104			`// Extended keys`
105			`case (scan_code)`
106			`8'h6B: begin // LEFT`
107			`keys[0][0] <= released; // CAPS SHIFT`
108			`keys[3][4] <= released; // 5`
109			`end`
110			`8'h72: begin // DOWN`
111			`keys[0][0] <= released; // CAPS SHIFT`
112			`keys[4][4] <= released; // 6`
113			`end`
114			`8'h75: begin // UP`
115			`keys[0][0] <= released; // CAPS SHIFT`
116			`keys[4][3] <= released; // 7`
117			`end`
118			`8'h74: begin // RIGHT`
119			`keys[0][0] <= released; // CAPS SHIFT`
120			`keys[4][2] <= released; // 8`
121			`end`
122			`endcase`
123			`end`
124			`else begin`
125			`// For each PS/2 scan-code, set the ZX keyboard matrix state`
126			`case (scan_code)`
127			`8'h12: shifted <= !released; // Local SHIFT key (left)`
128			`8'h59: shifted <= !released; // Local SHIFT key (right)`
129
130			`8'h14: keys[0][0] <= released; // CAPS SHIFT = Left or right Ctrl`
131
132			`8'h1A: keys[0][1] <= released; // Z`
133			`8'h22: keys[0][2] <= released; // X`
134			`8'h21: keys[0][3] <= released; // C`
135			`8'h2A: keys[0][4] <= released; // V`
136
137			`8'h1C: keys[1][0] <= released; // A`
138			`8'h1B: keys[1][1] <= released; // S`
139			`8'h23: keys[1][2] <= released; // D`
140			`8'h2B: keys[1][3] <= released; // F`
141			`8'h34: keys[1][4] <= released; // G`
142
143			`8'h15: keys[2][0] <= released; // Q`
144			`8'h1D: keys[2][1] <= released; // W`
145			`8'h24: keys[2][2] <= released; // E`
146			`8'h2D: keys[2][3] <= released; // R`
147			`8'h2C: keys[2][4] <= released; // T`
148
149			`8'h16: keys[3][0] <= released; // 1`
150			`8'h1E: keys[3][1] <= released; // 2`
151			`8'h26: keys[3][2] <= released; // 3`
152			`8'h25: keys[3][3] <= released; // 4`
153			`8'h2E: keys[3][4] <= released; // 5`
154
155			`8'h45: keys[4][0] <= released; // 0`
156			`8'h46: keys[4][1] <= released; // 9`
157			`8'h3E: keys[4][2] <= released; // 8`
158			`8'h3D: keys[4][3] <= released; // 7`
159			`8'h36: keys[4][4] <= released; // 6`
160
161			`8'h4D: keys[5][0] <= released; // P`
162			`8'h44: keys[5][1] <= released; // O`
163			`8'h43: keys[5][2] <= released; // I`
164			`8'h3C: keys[5][3] <= released; // U`
165			`8'h35: keys[5][4] <= released; // Y`
166
167			`8'h5A: keys[6][0] <= released; // ENTER`
168			`8'h4B: keys[6][1] <= released; // L`
169			`8'h42: keys[6][2] <= released; // K`
170			`8'h3B: keys[6][3] <= released; // J`
171			`8'h33: keys[6][4] <= released; // H`
172
173			`8'h29: keys[7][0] <= released; // SPACE`
174			`8'h11: keys[7][1] <= released; // SYMBOL SHIFT (Red) = Left and right Alt`
175			`8'h3A: keys[7][2] <= released; // M`
176			`8'h31: keys[7][3] <= released; // N`
177			`8'h32: keys[7][4] <= released; // B`
178
179			`8'h66: begin // BACKSPACE`
180			`keys[0][0] <= released;`
181			`keys[4][0] <= released;`
182			`end`
183			`8'h76: begin // ESC -> BREAK`
184			`keys[0][0] <= released; // CAPS SHIFT`
185			`keys[7][0] <= released; // SPACE`
186			`end`
187	13	gdevic	`// With shifted keys, we need to make inactive (set to 1) other corresponding key`
188			`// Otherwise, it will stay active if the shift was released first`
189	8	gdevic	`8'h4E: begin // - or (shifted) _`
190	13	gdevic	`keys[7][1] <= released; // SYMBOL SHIFT (Red)`
191			`keys[4][0] <= shifted ? released : 1; // 0`
192			`keys[6][3] <= shifted ? 1 : released; // J`
193	8	gdevic	`end`
194			`8'h55: begin // = or (shifted) +`
195	13	gdevic	`keys[7][1] <= released; // SYMBOL SHIFT (Red)`
196			`keys[6][2] <= shifted ? released : 1; // K`
197			`keys[6][1] <= shifted ? 1 : released; // L`
198	8	gdevic	`end`
199			`8'h52: begin // ' or (shifted) "`
200	13	gdevic	`keys[7][1] <= released; // SYMBOL SHIFT (Red)`
201			`keys[5][0] <= shifted ? released : 1; // P`
202			`keys[4][3] <= shifted ? 1 : released; // 7`
203	8	gdevic	`end`
204			`8'h4C: begin // ; or (shifted) :`
205	13	gdevic	`keys[7][1] <= released; // SYMBOL SHIFT (Red)`
206			`keys[0][1] <= shifted ? released : 1; // Z`
207			`keys[5][1] <= shifted ? 1 : released; // O`
208	8	gdevic	`end`
209			`8'h41: begin // , or (shifted) <`
210	13	gdevic	`keys[7][1] <= released; // SYMBOL SHIFT (Red)`
211			`keys[2][3] <= shifted ? released : 1; // R`
212			`keys[7][3] <= shifted ? 1 : released; // N`
213	8	gdevic	`end`
214			`8'h49: begin // . or (shifted) >`
215	13	gdevic	`keys[7][1] <= released; // SYMBOL SHIFT (Red)`
216			`keys[2][4] <= shifted ? released : 1; // T`
217			`keys[7][2] <= shifted ? 1 : released; // M`
218	8	gdevic	`end`
219			`8'h4A: begin // / or (shifted) ?`
220	13	gdevic	`keys[7][1] <= released; // SYMBOL SHIFT (Red)`
221			`keys[0][3] <= shifted ? released : 1; // C`
222			`keys[0][4] <= shifted ? 1 : released; // V`
223	8	gdevic	`end`
224			`endcase`
225			`end`
226			`end`
227			`end`
228			`end`
229
230			`endmodule`

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[/] [a-z80/] [trunk/] [host/] [zxspectrum_de1/] [ula/] [zx_kbd.sv] - Blame information for rev 13