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TinyAdder: Add docs, organise things, updated EAGLE files.

This commit is contained in:
Kyle Isom 2018-12-29 10:49:04 -08:00
parent 4770a2bd9c
commit b4d0799516
5 changed files with 4082 additions and 102 deletions
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37
fpga/tinyfpga/TinyAdder/README.md Normal file
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TinyAdder
========
TinyAdder is a 4-bit adder built on the TinyFPGA BX. It connects four
slide switches (I wanted actual toggle switches, but that's how it goes)
to a pair of 7-segment LCD displays.
Code organisation
-----------------
Currently there are two modules:
+ SegmentLCD: a little awkwardly named due to the naming constraints,
but this takes a 4-bit input number and outputs a 7-bit output. The
hookup requirements are described in the module comments.
+ TinyAdder: This is the top-level adder.
Hardware revisions
------------------
+ rev1 (2018-12-22)
+ rev2 (2018-12-22): realised that the LCDs were missing resistors;
I had been looking at a tutorial that used a shift register; the shift
register apparently had an internal current limiter so I assumed the
LCDs didn't need them. This was wrong. Fortunately I was able to cancel
the rev1 order before it went out.
+ rev3 (2018-12-28): after breadboarding the push button, I realised
I'd messed up the schematic (and accordingly, the board) by wiring
both ends of the push buttons to Vcc, which... isn't very useful at
all. I fixed it, but not before the rev2 was sent to the fab.
TODO
----
+ I'd like to have the two displays show the two numbers before adding
them. The 'hi' display could show the first addend, and the 'low' could
show the second addend, with live updating.

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fpga/tinyfpga/TinyAdder/SegmentLCD.v Normal file
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/// SegmentLCD represents a 7-segment display that takes as input a 4-bit
/// number and outputs the correct pin configuration. The pins need to be
/// wired as {G, F, E, D, C, B, A} for this to work.
///
/// For example,
///
/// wire [7:0] sum = 8'b00000000;
/// segment7 low (
/// .number(sum[3:0]),
/// .out({PIN_15, PIN_14, PIN_13, PIN_12, PIN_11, PIN_10, PIN_9})
/// );
module SegmentLCD (
input [3:0] number,
output [6:0] out = 7'b0000000
);
always @(*)
begin
case (number)
4'b0000: out <= 7'b0111111; // 0
4'b0001: out <= 7'b0000110; // 1
4'b0010: out <= 7'b1011011; // 2
4'b0011: out <= 7'b1001111; // 3
4'b0100: out <= 7'b1100110; // 4
4'b0101: out <= 7'b1101101; // 5
4'b0110: out <= 7'b1111101; // 6
4'b0111: out <= 7'b0000111; // 7
4'b1000: out <= 7'b1111111; // 8
4'b1001: out <= 7'b1100111; // 9
4'b1010: out <= 7'b1110111; // A
4'b1011: out <= 7'b1111100; // B
4'b1100: out <= 7'b0111001; // C
4'b1101: out <= 7'b1011110; // D
4'b1110: out <= 7'b1111001; // E
4'b1111: out <= 7'b1110001; // F
endcase
end
endmodule

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fpga/tinyfpga/TinyAdder/TinyAdder.v
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module segment7 (
input [3:0] number,
output [6:0] out = 7'b0000000
);
always @(*)
begin
case (number)
4'b0000: out <= 7'b0111111; // 0
4'b0001: out <= 7'b0000110; // 1
4'b0010: out <= 7'b1011011; // 2
4'b0011: out <= 7'b1001111; // 3
4'b0100: out <= 7'b1100110; // 4
4'b0101: out <= 7'b1101101; // 5
4'b0110: out <= 7'b1111101; // 6
4'b0111: out <= 7'b0000111; // 7
4'b1000: out <= 7'b1111111; // 8
4'b1001: out <= 7'b1100111; // 9
4'b1010: out <= 7'b1110111; // A
4'b1011: out <= 7'b1111100; // B
4'b1100: out <= 7'b0111001; // C
4'b1101: out <= 7'b1011110; // D
4'b1110: out <= 7'b1111001; // E
4'b1111: out <= 7'b1110001; // F
endcase
end
endmodule
// look in pins.pcf for all the pin names on the TinyFPGA BX board
module TinyAdder (
input CLK, // 16MHz clock
input PIN_1, // A[0]
input PIN_2, // A[1]
input PIN_3, // A[2]
input PIN_4, // A[3]
input PIN_5, // EXEC
input PIN_6, // CLR
// 7-segment LCD displays
output PIN_9, // LOW/A
output PIN_10, // LOW/B
output PIN_11, // LOW/C
output PIN_12, // LOW/D
output PIN_13, // LOW/E
output PIN_14, // LOW/F
output PIN_15, // LOW/G
output PIN_16, // HI/A
output PIN_17, // HI/B
output PIN_18, // HI/C
output PIN_19, // HI/D
output PIN_20, // HI/E
output PIN_21, // HI/F
output PIN_22, // HI/G
output LED, // User/boot LED next to power LED
output USBPU // USB pull-up resistor
);
// drive USB pull-up resistor to '0' to disable USB
assign USBPU = 0;
wire [7:0] sum = 8'b00000000;
wire [3:0] switches;
assign switches = {PIN_4, PIN_3, PIN_2, PIN_1};
// state determines what happens when the button is pressed.
reg [1:0] state = 2'b00;
assign LED = state[0];
segment7 low (
.number(sum[3:0]),
.out({PIN_15, PIN_14, PIN_13, PIN_12, PIN_11, PIN_10, PIN_9})
);
segment7 hi (
.number(sum[7:4]),
.out({PIN_22, PIN_21, PIN_20, PIN_19, PIN_18, PIN_17, PIN_16})
);
always @(PIN_5)
begin
case (state)
2'b00: begin
sum = switches;
state <= 2'b01;
end
2'b01: begin
sum = sum + switches;
state = 2'b10;
end
endcase
end
always @(PIN_6)
begin
state <= 2'b00;
sum = 7'b0000000;
end
endmodule
`include "SegmentLCD.v"
/////////////////////////////////////////////////////////////////////////
/// TinyAdder.v
/// Author: K. Isom
/// Created: 2018-12-27
/////////////////////////////////////////////////////////////////////////
/// TinyAdder is a 4-bit adder that displays calculations on a pair of
/// 7-segment LCDs. The EXEC button doubles as a plus and equals button:
/// the first time it is pressed, entry begins with the second number. The
/// second time it is pressed, the sum of the two numbers is shown on the
/// display.
module TinyAdder (
input PIN_1, // A[0]
input PIN_2, // A[1]
input PIN_3, // A[2]
input PIN_4, // A[3]
input PIN_5, // EXEC
input PIN_6, // CLR
// There are two 7-segment displays: 'low' shows the 4 LSBs, and 'hi'
// shows the 4 MSBs. That is, given 0x12, 'low' would display '2' and
// 'hi' would show '1'.
output PIN_9, // LOW/A
output PIN_10, // LOW/B
output PIN_11, // LOW/C
output PIN_12, // LOW/D
output PIN_13, // LOW/E
output PIN_14, // LOW/F
output PIN_15, // LOW/G
output PIN_16, // HI/A
output PIN_17, // HI/B
output PIN_18, // HI/C
output PIN_19, // HI/D
output PIN_20, // HI/E
output PIN_21, // HI/F
output PIN_22, // HI/G
output LED, // User/boot LED next to power LED
output USBPU // USB pull-up resistor
);
// Drive USB pull-up resistor to '0' to disable USB. This prevents us
// from falling back into the bootloader, I think.
assign USBPU = 0;
wire [7:0] sum = 8'b00000000;
wire [3:0] switches;
assign switches = {PIN_4, PIN_3, PIN_2, PIN_1};
// state determines what happens when the button is pressed.
reg [1:0] state = 2'b00;
segment7 low (
.number(sum[3:0]),
.out({PIN_15, PIN_14, PIN_13, PIN_12, PIN_11, PIN_10, PIN_9})
);
segment7 hi (
.number(sum[7:4]),
.out({PIN_22, PIN_21, PIN_20, PIN_19, PIN_18, PIN_17, PIN_16})
);
// When EXEC is pressed, the adder's state is advanced. There are
// three states:
// + state 00: entry of the first number.
// + state 01: entry of the second number.
// + state 10: the sum of the two numbers is displayed. Pressing
// exec again resets the display.
always @(negedge PIN_5)
begin
case (state)
2'b00: begin
sum = switches;
state <= 2'b01;
end
2'b01: begin
sum = sum + switches;
state = 2'b10;
LED <= 1;
end
2'b10: begin
sum = 8'b00000000;
state = 2'b00;
LED <= 0;
end
endcase
end
// When CLEAR is pressed, the adder should go back to its initial
// state.
always @(negedge PIN_6)
begin
state <= 2'b00;
sum = 8'b0000000;
LED <= 0;
end
endmodule

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fpga/tinyfpga/TinyAdder/tinyadder_r3.sch Normal file
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