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Commit 2ecfb943 authored by Mike Lyons's avatar Mike Lyons
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Switching to sampled SPI_CLK solution dependent on fast system clock rather than two clock domains

parent 94c99edd
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src/spi_base/spiifc.v
View file @ 2ecfb943
......@@ -3,7 +3,7 @@
// Company:
// Engineer:
//
// Create Date: 19:24:33 10/18/2011
// Create Date: 16:46:12 03/02/2012
// Design Name:
// Module Name: spiifc
// Project Name:
......@@ -31,452 +31,129 @@ module spiifc(
rcMemData,
rcMemWE,
debug_out
);
//
// Parameters
//
parameter AddrBits = 12;
// Defines
`define CMD_READ_START 8'd1
`define CMD_READ_MORE 8'd2
`define CMD_WRITE_START 8'd3
`define STATE_GET_CMD 8'd0
`define STATE_READING 8'd1
`define STATE_WRITING 8'd2
//
// Input/Output defs
//
input Reset;
input SysClk;
input SPI_CLK;
output SPI_MISO;
input SPI_MOSI;
input SPI_SS;
output [AddrBits-1:0] txMemAddr;
input [7:0] txMemData;
output [AddrBits-1:0] rcMemAddr;
output [7:0] rcMemData;
output rcMemWE;
output [7:0] debug_out;
//
// Registers
//
reg [ 7: 0] debug_reg;
reg [ 7: 0] rcByteReg;
reg rcStarted;
reg [ 2: 0] rcBitIndexReg;
reg [11: 0] rcMemAddrReg;
reg [11: 0] rcMemAddrNext;
reg [ 7: 0] rcMemDataReg;
reg rcMemWEReg;
reg ssPrev;
reg ssFastToggleReg;
reg ssSlowToggle;
reg ssTurnOnReg;
reg ssTurnOnHandled;
reg [ 7: 0] cmd;
reg [ 7: 0] stateReg;
reg [11: 0] txMemAddrReg;
reg [ 2: 0] txBitAddr;
//
// Wires
//
wire rcByteValid;
wire [ 7: 0] rcByte;
wire rcStarting;
wire [ 2: 0] rcBitIndex;
wire ssTurnOn;
wire ssFastToggle;
wire [ 7: 0] state;
wire txMemAddrReset;
//
// Output assigns
//
assign debug_out = debug_reg;
assign rcMemAddr = rcMemAddrReg;
assign rcMemData = rcMemDataReg;
assign rcMemWE = rcMemWEReg;
assign txMemAddrReset = (rcByteValid && rcByte == `CMD_WRITE_START ? 1 : 0);
assign txMemAddr = (txMemAddrReset ? 0 : txMemAddrReg);
assign SPI_MISO = txMemData[txBitAddr];
assign ssFastToggle =
(ssPrev == 1 && SPI_SS == 0 ? ~ssFastToggleReg : ssFastToggleReg);
//
// Wire assigns
//
assign rcByteValid = rcStarted && rcBitIndex == 0;
assign rcByte = {rcByteReg[7:1], SPI_MOSI};
assign rcStarting = ssTurnOn;
assign rcBitIndex = (rcStarting ? 3'd7 : rcBitIndexReg);
assign ssTurnOn = ssSlowToggle ^ ssFastToggle;
assign state = (rcStarting ? `STATE_GET_CMD : stateReg);
initial begin
ssSlowToggle <= 0;
end
always @(posedge SysClk) begin
ssPrev <= SPI_SS;
if (Reset) begin
ssTurnOnReg <= 0;
ssFastToggleReg <= 0;
end else begin
if (ssPrev & (~SPI_SS)) begin
ssTurnOnReg <= 1;
ssFastToggleReg <= ~ssFastToggleReg;
end else if (ssTurnOnHandled) begin
ssTurnOnReg <= 0;
end
end
end
always @(posedge SPI_CLK) begin
ssSlowToggle <= ssFastToggle;
if (Reset) begin
// Resetting
rcByteReg <= 8'h00;
rcStarted <= 0;
rcBitIndexReg <= 3'd7;
ssTurnOnHandled <= 0;
debug_reg <= 8'hFF;
end else begin
// Not resetting
ssTurnOnHandled <= ssTurnOn;
stateReg <= state;
rcMemAddrReg <= rcMemAddrNext;
if (~SPI_SS) begin
rcByteReg[rcBitIndex] <= SPI_MOSI;
rcBitIndexReg <= rcBitIndex - 3'd1;
rcStarted <= 1;
// Update txBitAddr if writing out
if (`STATE_WRITING == state) begin
if (txBitAddr == 3'd1) begin
txMemAddrReg <= txMemAddr + 1;
end
txBitAddr <= txBitAddr - 1;
end
end
// We've just received a byte (well, currently receiving the last bit)
if (rcByteValid) begin
// For now, just display on LEDs
debug_reg <= rcByte;
if (`STATE_GET_CMD == state) begin
cmd <= rcByte; // Will take effect next cycle
if (`CMD_READ_START == rcByte) begin
rcMemAddrNext <= 0;
stateReg <= `STATE_READING;
end else if (`CMD_READ_MORE == rcByte) begin
stateReg <= `STATE_READING;
end else if (`CMD_WRITE_START == rcByte) begin
txBitAddr <= 3'd7;
stateReg <= `STATE_WRITING;
txMemAddrReg <= txMemAddr; // Keep at 0
end
end else if (`STATE_READING == state) begin
rcMemDataReg <= rcByte;
rcMemAddrNext <= rcMemAddr + 1;
rcMemWEReg <= 1;
end else if (`STATE_WRITING == state) begin
txBitAddr <= 3'd7;
stateReg <= `STATE_WRITING;
end
end else begin
// Not a valid byte
rcMemWEReg <= 0;
end // valid/valid' byte
end // Reset/Reset'
end
/*
reg rcByte_valid;
wire rcClockBridgeEmpty;
wire readRcByte;
assign getRcByte = ~rcClockBridgeEmpty;
wire rcClockBridgeReadValid;
wire rcClockBridgeFull;
wire [7:0] rcByte;
clock_bridge recvClockBridge (
.rst(Reset), // input rst
.wr_clk(~SPI_CLK), // input wr_clk
.rd_clk(SysClk), // input rd_clk
.din(SPI_MOSI), // input [0 : 0] din
.wr_en(~SPI_SS), // input wr_en
.rd_en(getRcByte), // input rd_en
.dout(rcByte), // output [7 : 0] dout
.full(rcClockBridgeFull), // output full
.empty(rcClockBridgeEmpty), // output empty
.valid(rcClockBridgeReadValid) // output valid
);
always @(posedge SysClk) begin
rcByte_valid <= getRcByte;
end
wire txCmdClkBridgeEmpty;
wire txCmdClkBridgeFull;
wire [7:0] txCmd;
wire txCmdValid;
assign txCmdValid = ~txCmdClkBridgeEmpty;
wire postTxCmd;
assign postTxCmd =
fifo_8bit_to_8bit txCmdClkBridge(
.rst(Reset), // input rst
.wr_clk(SysClk), // input wr_clk
.rd_clk(SPI_CLK), // input rd_clk
.din(din), // input [7 : 0] din
.wr_en(post), // input wr_en
.rd_en(txCmdValid), // input rd_en
.dout(txCmd), // output [7 : 0] dout
.full(txCmdClkBridgeFull), // output full
.empty(txCmdClkBridgeEmpty) // output empty
);
//
// Parameters
//
parameter AddrBits = 12;
//
// Defines
//
`define CMD_READ_START 8'd1
`define CMD_READ_MORE 8'd2
`define CMD_WRITE_START 8'd3
`define CMD_WRITE_MORE 8'd4
`define CMD_INTERRUPT 8'd5
`define STATE_GET_CMD 8'd0
`define STATE_READING 8'd1
`define STATE_WRITING 8'd2
`define STATE_WRITE_INTR 8'd3
//
// TRANSMIT: FPGA TO PC
//
assign SPI_MISO = txMemData[bitIndex];
reg [2:0] bitIndex;
reg [AddrBits-1:0] byteAddr;
assign txMemAddr = byteAddr;
reg [7:0] debug_reg;
assign debug_out = debug_reg;
//
// Input/Outputs
//
input Reset;
input SysClk;
input SPI_CLK;
output SPI_MISO; // outgoing (from respect of this module)
input SPI_MOSI; // incoming (from respect of this module)
input SPI_SS;
output [AddrBits-1:0] txMemAddr; // outgoing data
input [7:0] txMemData;
output [AddrBits-1:0] rcMemAddr; // incoming data
output [7:0] rcMemData;
output rcMemWE;
output [7:0] debug_out;
initial begin
debug_reg <= 8'h00;
//rcState <= 0;
end
//
// Registers
//
reg prev_spiClk; // Value of SPI_CLK during last SysClk cycle
reg prev_spiSS; // Value of SPI_SS during last SysClk cycle
reg [7:0] state_reg; // Register backing the 'state' wire
reg [7:0] rcByte_reg; // Register backing 'rcByte'
reg [2:0] rcBitIndex_reg; // Register backing 'rcBitIndex'
reg [AddrBits-1:0] rcMemAddr_reg; // Byte addr to write MOSI data to
//
// Clocked logic
//
always @(posedge SPI_CLK) begin
if (Reset) begin
bitIndex <= 3'd0;
byteAddr <= 0;
end else if (SPI_SS == 1'b0) begin
bitIndex <= bitIndex - 3'd1;
if (bitIndex == 3'd1) begin
byteAddr <= byteAddr + 1;
end
end
end
//
// RECEIVE: PC TO FPGA
//
// Detect start of receive
reg ss_prev;
wire ss_negedge;
always @(posedge SysClk) begin
ss_prev <= SPI_SS;
end
assign ss_negedge = (ss_prev == 1'b1 && SPI_SS == 1'b0 ? 1'b1 : 1'b0);
`define RC_MODE_GET_STATUS 8'd0
`define RC_MODE_GET_BUFFER 8'd1
`define RC_MODE_PUT_BUFFER 8'd2
reg [7:0] rcMode;
`define RC_STATE_CMD 8'd0
`define RC_STATE_SIZE 8'd1
`define RC_STATE_PAYLOAD 8'd2
reg [7:0] rcState;
reg [31:0] rcByteCount;
reg [31:0] rcByteSize;
reg [7:0] rcMemData_reg;
reg [AddrBits-1:0] rcMemAddr_reg;
reg rcMemWE_reg;
assign rcMemData = rcMemData_reg;
assign rcMemAddr = rcMemAddr_reg;
assign rcMemWE = rcMemWE_reg;
always @(posedge SysClk) begin
// // About to receive
// if (ss_negedge) begin
// rcBitIndex <= 3'd7;
// rcState <= `RC_STATE_CMD;
//
// debug_reg[0] <= 1;
// end
//
// // Receiving
// if (receiving) begin
// rcByte[rcBitIndex] <= SPI_MOSI;
// rcBitIndex <= rcBitIndex - 3'd1;
// end
// rcByte_valid <= (receiving && rcBitIndex == 3'd0 ? 1'b1 : 1'b0);
// Handle the complete incoming byte
if (rcByte_valid) begin
debug_reg[7:4] <= rcByte[3:0];
//
// Wires
//
wire risingSpiClk; // Did the SPI_CLK rise since last SysClk cycle?
wire validSpiBit; // Are the SPI MOSI/MISO bits new and valid?
reg state; // Current state in the module's state machine (always @* effectively wire)
wire rcByteValid; // rcByte is valid and new
wire [7:0] rcByte; // Byte received from master
wire [2:0] rcBitIndex; // Bit of rcByte to write to next
// First byte: the command
if (`RC_STATE_CMD == rcState || ss_negedge) begin
// Disable writing to the read buffer (will be left on if the prev
// cycle was writing to it)
rcMemWE_reg <= 1'b0;
// Detect new valid bit
always @(posedge SysClk) begin
prev_spiClk <= SPI_CLK;
end
assign risingSpiClk = SPI_CLK & (~prev_spiClk);
assign validSpiBit = risingSpiClk & (~SPI_SS);
debug_reg[0] <= 1;
// Decode the SPI command
case (rcByte)
`RC_MODE_GET_STATUS: begin end // no status yet
`RC_MODE_GET_BUFFER: begin rcMode <= `RC_MODE_GET_BUFFER; rcState <= `RC_STATE_SIZE; end
`RC_MODE_PUT_BUFFER: begin rcMode <= `RC_MODE_PUT_BUFFER; rcState <= `RC_STATE_SIZE; end
endcase
// Initialize counters
rcByteCount <= 32'd0;
rcByteSize <= 32'd0;
end
// Record size (in bytes) of payload
if (`RC_STATE_SIZE == rcState) begin
debug_reg[1] <= 1;
case (rcByteCount)
32'd0: begin rcByteSize[31:24] <= rcByte; rcByteCount <= 32'd1; end
32'd1: begin rcByteSize[23:16] <= rcByte; rcByteCount <= 32'd2; end
32'd2: begin rcByteSize[15: 8] <= rcByte; rcByteCount <= 32'd3; end
32'd3: begin
rcByteSize[ 7: 0] <= rcByte;
rcByteCount <= 32'd0;
rcState <= `RC_STATE_PAYLOAD;
rcByteCount <= 32'd0;
if (`RC_MODE_GET_BUFFER == rcMode) begin
// TODO: want reset tx byte addr here probably
end
end
endcase
end
// The payload
if (rcState == `RC_STATE_PAYLOAD) begin
debug_reg[2] <= 1;
case (rcMode)
`RC_MODE_GET_BUFFER: begin
// IGNORE EVERYTHING SO STUFF CAN BE READ OUT
end
`RC_MODE_PUT_BUFFER: begin
//debug_reg[4] <= 1;
rcMemWE_reg <= 1'b1;
rcMemData_reg <= rcByte;
rcMemAddr_reg <= rcByteCount[AddrBits-1:0];
end
endcase
// Detect new SPI packet (SS dropped low)
always @(posedge SysClk) begin
prev_spiSS <= SPI_SS;
end
assign packetStart = prev_spiSS & (~SPI_SS);
if (rcByteCount == rcByteSize - 1) begin
rcState <= `RC_STATE_CMD;
//debug_reg[5] <= 1;
end else begin
rcByteCount <= rcByteCount + 32'd1;
end
end
end
else begin // not valid byte
if (ss_negedge) begin
rcState <= `RC_STATE_CMD;
end
end
// Build incoming byte
always @(posedge SysClk) begin
if (validSpiBit) begin
rcByte_reg[rcBitIndex] <= SPI_MOSI;
rcBitIndex_reg <= (rcBitIndex > 0 ? rcBitIndex - 1 : 7);
end else begin
rcBitIndex_reg <= rcBitIndex;
end
//reg [7:0] rcByteReg;
//wire [7:0] rcByte;
//assign rcByte = {rcByteReg[7:1], (SPI_SS == 1'b0 && bitIndex ==
end
assign rcBitIndex = (Reset || packetStart ? 7 : rcBitIndex_reg);
assign rcByte = {rcByte_reg[7:1], SPI_MOSI};
assign rcByteValid = (validSpiBit && rcBitIndex == 0 ? 1 : 0);
// Incoming MOSI data buffer management
assign rcMemAddr = rcMemAddr_reg;
assign rcMemData = rcByte;
assign rcMemWE = (state == `STATE_READING && rcByteValid ? 1 : 0);
always @(posedge SysClk) begin
if (Reset || (`STATE_GET_CMD == state && rcByteValid)) begin
rcMemAddr_reg <= 0;
end else if (rcMemWE) begin
rcMemAddr_reg <= rcMemAddr + 1;
end else begin
rcMemAddr_reg <= rcMemAddr;
end
end
// State machine
always @(*) begin
if (Reset || packetStart) begin
state <= `STATE_GET_CMD;
end else if (state_reg == `STATE_GET_CMD && rcByteValid) begin
state <= rcByte;
end else begin
state <= state_reg;
end
end
always @(posedge SysClk) begin
if (`STATE_GET_CMD == state && rcByteValid) begin
if (`CMD_READ_START == rcByte) begin
state_reg <= `STATE_READING;
end else if (`CMD_READ_MORE == rcByte) begin
state_reg <= `STATE_READING;
end else if (`CMD_WRITE_START == rcByte) begin
state_reg <= `STATE_WRITING;
end else if (`CMD_WRITE_MORE == rcByte) begin
state_reg <= `STATE_WRITING;
end else if (`CMD_INTERRUPT == rcByte) begin
// TODO: NYI
end
end else begin
state_reg <= state;
end
end
// //
// // Receive (GPU to SPI)
// //
// reg SPI_SS_prev_cycle;
//
// // This is the register backing rcByteId. It is always one cycle
// // behind the true value of rcByteId, which we have to do a little
// // work to get instantaneously correct using wire logic.
// reg [31:0] rcByteIdPrev;
// wire [31:0] rcByteId;
// assign rcByteId = (SPI_SS_prev_cycle == 1 && SPI_SS == 0 ? 32'd0 : 32'd1 + rcByteIdPrev);
//
// // 1 if we're receiving from GPC, 0 if not.
// wire isRecv;
// assign isRecv = ~SPI_SS;
//
// // Bits to Byte aggregator
// reg [2:0] rcBitId;
// reg [7:0] rcByte;
//
//
// reg [31:0] rcSizeBytes;
//
// always @(posedge SPI_CLK) begin
// if (1 == isRecv) begin
// case (rcByteId)
// 0: rcSizeBytes[ 7: 0] <=
// end
//
// // Update registers for next cycle
// SPI_SS_prev_cycle <= SPI_SS;
// rcByteId <= rcByteIdPrev;
// end
*/
endmodule
src/spi_base/spiifc_fastclock.v deleted 100644 → 0
View file @ 94c99edd
`timescale 1ns / 1ps
//////////////////////////////////////////////////////////////////////////////////
// Company:
// Engineer:
//
// Create Date: 16:46:12 03/02/2012
// Design Name:
// Module Name: spiifc
// Project Name:
// Target Devices:
// Tool versions:
// Description:
//
// Dependencies:
//
// Revision:
// Revision 0.01 - File Created
// Additional Comments:
//
//////////////////////////////////////////////////////////////////////////////////
module spiifc(
Reset,
SysClk,
SPI_CLK,
SPI_MISO,
SPI_MOSI,
SPI_SS,
txMemAddr,
txMemData,
rcMemAddr,
rcMemData,
rcMemWE,
debug_out
);
//
// Parameters
//
parameter AddrBits = 12;
//
// Defines
//
`define CMD_READ_START 8'd1
`define CMD_READ_MORE 8'd2
`define CMD_WRITE_START 8'd3
`define CMD_WRITE_MORE 8'd4
`define CMD_INTERRUPT 8'd5
`define STATE_GET_CMD 8'd0
`define STATE_READING 8'd1
`define STATE_WRITING 8'd2
`define STATE_WRITE_INTR 8'd3
//
// Input/Outputs
//
input Reset;
input SysClk;
input SPI_CLK;
output SPI_MISO; // outgoing (from respect of this module)
input SPI_MOSI; // incoming (from respect of this module)
input SPI_SS;
output [AddrBits-1:0] txMemAddr; // outgoing data
input [7:0] txMemData;
output [AddrBits-1:0] rcMemAddr; // incoming data
output [7:0] rcMemData;
output rcMemWE;
output [7:0] debug_out;
//
// Registers
//
reg prev_spiClk; // Value of SPI_CLK during last SysClk cycle
reg prev_spiSS; // Value of SPI_SS during last SysClk cycle
reg [7:0] state_reg; // Register backing the 'state' wire
reg [7:0] rcByte_reg; // Register backing 'rcByte'
reg [2:0] rcBitIndex_reg; // Register backing 'rcBitIndex'
reg [AddrBits-1:0] rcMemAddr_reg; // Byte addr to write MOSI data to
//
// Wires
//
wire risingSpiClk; // Did the SPI_CLK rise since last SysClk cycle?
wire validSpiBit; // Are the SPI MOSI/MISO bits new and valid?
reg state; // Current state in the module's state machine (always @* effectively wire)
wire rcByteValid; // rcByte is valid and new
wire [7:0] rcByte; // Byte received from master
wire [2:0] rcBitIndex; // Bit of rcByte to write to next
// Detect new valid bit
always @(posedge SysClk) begin
prev_spiClk <= SPI_CLK;
end
assign risingSpiClk = SPI_CLK & (~prev_spiClk);
assign validSpiBit = risingSpiClk & (~SPI_SS);
// Detect new SPI packet (SS dropped low)
always @(posedge SysClk) begin
prev_spiSS <= SPI_SS;
end
assign packetStart = prev_spiSS & (~SPI_SS);
// Build incoming byte
always @(posedge SysClk) begin
if (validSpiBit) begin
rcByte_reg[rcBitIndex] <= SPI_MOSI;
rcBitIndex_reg <= (rcBitIndex > 0 ? rcBitIndex - 1 : 7);
end else begin
rcBitIndex_reg <= rcBitIndex;
end
end
assign rcBitIndex = (Reset || packetStart ? 7 : rcBitIndex_reg);
assign rcByte = {rcByte_reg[7:1], SPI_MOSI};
assign rcByteValid = (validSpiBit && rcBitIndex == 0 ? 1 : 0);
// Incoming MOSI data buffer management
assign rcMemAddr = rcMemAddr_reg;
assign rcMemData = rcByte;
assign rcMemWE = (state == `STATE_READING && rcByteValid ? 1 : 0);
always @(posedge SysClk) begin
if (Reset || (`STATE_GET_CMD == state && rcByteValid)) begin
rcMemAddr_reg <= 0;
end else if (rcMemWE) begin
rcMemAddr_reg <= rcMemAddr + 1;
end else begin
rcMemAddr_reg <= rcMemAddr;
end
end
// State machine
always @(*) begin
if (Reset || packetStart) begin
state <= `STATE_GET_CMD;
end else if (state_reg == `STATE_GET_CMD && rcByteValid) begin
state <= rcByte;
end else begin
state <= state_reg;
end
end
always @(posedge SysClk) begin
if (`STATE_GET_CMD == state && rcByteValid) begin
if (`CMD_READ_START == rcByte) begin
state_reg <= `STATE_READING;
end else if (`CMD_READ_MORE == rcByte) begin
state_reg <= `STATE_READING;
end else if (`CMD_WRITE_START == rcByte) begin
state_reg <= `STATE_WRITING;
end else if (`CMD_WRITE_MORE == rcByte) begin
state_reg <= `STATE_WRITING;
end else if (`CMD_INTERRUPT == rcByte) begin
// TODO: NYI
end
end else begin
state_reg <= state;
end
end
endmodule
src/spi_base/spiifc_twoclock.v 0 → 100644
View file @ 2ecfb943
`timescale 1ns / 1ps
//////////////////////////////////////////////////////////////////////////////////
// Company:
// Engineer:
//
// Create Date: 19:24:33 10/18/2011
// Design Name:
// Module Name: spiifc
// Project Name:
// Target Devices:
// Tool versions:
// Description:
//
// Dependencies:
//
// Revision:
// Revision 0.01 - File Created
// Additional Comments:
//
//////////////////////////////////////////////////////////////////////////////////
module spiifc(
Reset,
SysClk,
SPI_CLK,
SPI_MISO,
SPI_MOSI,
SPI_SS,
txMemAddr,
txMemData,
rcMemAddr,
rcMemData,
rcMemWE,
debug_out
);
//
// Parameters
//
parameter AddrBits = 12;
// Defines
`define CMD_READ_START 8'd1
`define CMD_READ_MORE 8'd2
`define CMD_WRITE_START 8'd3
`define STATE_GET_CMD 8'd0
`define STATE_READING 8'd1
`define STATE_WRITING 8'd2
//
// Input/Output defs
//
input Reset;
input SysClk;
input SPI_CLK;
output SPI_MISO;
input SPI_MOSI;
input SPI_SS;
output [AddrBits-1:0] txMemAddr;
input [7:0] txMemData;
output [AddrBits-1:0] rcMemAddr;
output [7:0] rcMemData;
output rcMemWE;
output [7:0] debug_out;
//
// Registers
//
reg [ 7: 0] debug_reg;
reg [ 7: 0] rcByteReg;
reg rcStarted;
reg [ 2: 0] rcBitIndexReg;
reg [11: 0] rcMemAddrReg;
reg [11: 0] rcMemAddrNext;
reg [ 7: 0] rcMemDataReg;
reg rcMemWEReg;
reg ssPrev;
reg ssFastToggleReg;
reg ssSlowToggle;
reg ssTurnOnReg;
reg ssTurnOnHandled;
reg [ 7: 0] cmd;
reg [ 7: 0] stateReg;
reg [11: 0] txMemAddrReg;
reg [ 2: 0] txBitAddr;
//
// Wires
//
wire rcByteValid;
wire [ 7: 0] rcByte;
wire rcStarting;
wire [ 2: 0] rcBitIndex;
wire ssTurnOn;
wire ssFastToggle;
wire [ 7: 0] state;
wire txMemAddrReset;
//
// Output assigns
//
assign debug_out = debug_reg;
assign rcMemAddr = rcMemAddrReg;
assign rcMemData = rcMemDataReg;
assign rcMemWE = rcMemWEReg;
assign txMemAddrReset = (rcByteValid && rcByte == `CMD_WRITE_START ? 1 : 0);
assign txMemAddr = (txMemAddrReset ? 0 : txMemAddrReg);
assign SPI_MISO = txMemData[txBitAddr];
assign ssFastToggle =
(ssPrev == 1 && SPI_SS == 0 ? ~ssFastToggleReg : ssFastToggleReg);
//
// Wire assigns
//
assign rcByteValid = rcStarted && rcBitIndex == 0;
assign rcByte = {rcByteReg[7:1], SPI_MOSI};
assign rcStarting = ssTurnOn;
assign rcBitIndex = (rcStarting ? 3'd7 : rcBitIndexReg);
assign ssTurnOn = ssSlowToggle ^ ssFastToggle;
assign state = (rcStarting ? `STATE_GET_CMD : stateReg);
initial begin
ssSlowToggle <= 0;
end
always @(posedge SysClk) begin
ssPrev <= SPI_SS;
if (Reset) begin
ssTurnOnReg <= 0;
ssFastToggleReg <= 0;
end else begin
if (ssPrev & (~SPI_SS)) begin
ssTurnOnReg <= 1;
ssFastToggleReg <= ~ssFastToggleReg;
end else if (ssTurnOnHandled) begin
ssTurnOnReg <= 0;
end
end
end
always @(posedge SPI_CLK) begin
ssSlowToggle <= ssFastToggle;
if (Reset) begin
// Resetting
rcByteReg <= 8'h00;
rcStarted <= 0;
rcBitIndexReg <= 3'd7;
ssTurnOnHandled <= 0;
debug_reg <= 8'hFF;
end else begin
// Not resetting
ssTurnOnHandled <= ssTurnOn;
stateReg <= state;
rcMemAddrReg <= rcMemAddrNext;
if (~SPI_SS) begin
rcByteReg[rcBitIndex] <= SPI_MOSI;
rcBitIndexReg <= rcBitIndex - 3'd1;
rcStarted <= 1;
// Update txBitAddr if writing out
if (`STATE_WRITING == state) begin
if (txBitAddr == 3'd1) begin
txMemAddrReg <= txMemAddr + 1;
end
txBitAddr <= txBitAddr - 1;
end
end
// We've just received a byte (well, currently receiving the last bit)
if (rcByteValid) begin
// For now, just display on LEDs
debug_reg <= rcByte;
if (`STATE_GET_CMD == state) begin
cmd <= rcByte; // Will take effect next cycle
if (`CMD_READ_START == rcByte) begin
rcMemAddrNext <= 0;
stateReg <= `STATE_READING;
end else if (`CMD_READ_MORE == rcByte) begin
stateReg <= `STATE_READING;
end else if (`CMD_WRITE_START == rcByte) begin
txBitAddr <= 3'd7;
stateReg <= `STATE_WRITING;
txMemAddrReg <= txMemAddr; // Keep at 0
end
end else if (`STATE_READING == state) begin
rcMemDataReg <= rcByte;
rcMemAddrNext <= rcMemAddr + 1;
rcMemWEReg <= 1;
end else if (`STATE_WRITING == state) begin
txBitAddr <= 3'd7;
stateReg <= `STATE_WRITING;
end
end else begin
// Not a valid byte
rcMemWEReg <= 0;
end // valid/valid' byte
end // Reset/Reset'
end
/*
reg rcByte_valid;
wire rcClockBridgeEmpty;
wire readRcByte;
assign getRcByte = ~rcClockBridgeEmpty;
wire rcClockBridgeReadValid;
wire rcClockBridgeFull;
wire [7:0] rcByte;
clock_bridge recvClockBridge (
.rst(Reset), // input rst
.wr_clk(~SPI_CLK), // input wr_clk
.rd_clk(SysClk), // input rd_clk
.din(SPI_MOSI), // input [0 : 0] din
.wr_en(~SPI_SS), // input wr_en
.rd_en(getRcByte), // input rd_en
.dout(rcByte), // output [7 : 0] dout
.full(rcClockBridgeFull), // output full
.empty(rcClockBridgeEmpty), // output empty
.valid(rcClockBridgeReadValid) // output valid
);
always @(posedge SysClk) begin
rcByte_valid <= getRcByte;
end
wire txCmdClkBridgeEmpty;
wire txCmdClkBridgeFull;
wire [7:0] txCmd;
wire txCmdValid;
assign txCmdValid = ~txCmdClkBridgeEmpty;
wire postTxCmd;
assign postTxCmd =
fifo_8bit_to_8bit txCmdClkBridge(
.rst(Reset), // input rst
.wr_clk(SysClk), // input wr_clk
.rd_clk(SPI_CLK), // input rd_clk
.din(din), // input [7 : 0] din
.wr_en(post), // input wr_en
.rd_en(txCmdValid), // input rd_en
.dout(txCmd), // output [7 : 0] dout
.full(txCmdClkBridgeFull), // output full
.empty(txCmdClkBridgeEmpty) // output empty
);
//
// TRANSMIT: FPGA TO PC
//
assign SPI_MISO = txMemData[bitIndex];
reg [2:0] bitIndex;
reg [AddrBits-1:0] byteAddr;
assign txMemAddr = byteAddr;
reg [7:0] debug_reg;
assign debug_out = debug_reg;
initial begin
debug_reg <= 8'h00;
//rcState <= 0;
end
//
// Clocked logic
//
always @(posedge SPI_CLK) begin
if (Reset) begin
bitIndex <= 3'd0;
byteAddr <= 0;
end else if (SPI_SS == 1'b0) begin
bitIndex <= bitIndex - 3'd1;
if (bitIndex == 3'd1) begin
byteAddr <= byteAddr + 1;
end
end
end
//
// RECEIVE: PC TO FPGA
//
// Detect start of receive
reg ss_prev;
wire ss_negedge;
always @(posedge SysClk) begin
ss_prev <= SPI_SS;
end
assign ss_negedge = (ss_prev == 1'b1 && SPI_SS == 1'b0 ? 1'b1 : 1'b0);
`define RC_MODE_GET_STATUS 8'd0
`define RC_MODE_GET_BUFFER 8'd1
`define RC_MODE_PUT_BUFFER 8'd2
reg [7:0] rcMode;
`define RC_STATE_CMD 8'd0
`define RC_STATE_SIZE 8'd1
`define RC_STATE_PAYLOAD 8'd2
reg [7:0] rcState;
reg [31:0] rcByteCount;
reg [31:0] rcByteSize;
reg [7:0] rcMemData_reg;
reg [AddrBits-1:0] rcMemAddr_reg;
reg rcMemWE_reg;
assign rcMemData = rcMemData_reg;
assign rcMemAddr = rcMemAddr_reg;
assign rcMemWE = rcMemWE_reg;
always @(posedge SysClk) begin
// // About to receive
// if (ss_negedge) begin
// rcBitIndex <= 3'd7;
// rcState <= `RC_STATE_CMD;
//
// debug_reg[0] <= 1;
// end
//
// // Receiving
// if (receiving) begin
// rcByte[rcBitIndex] <= SPI_MOSI;
// rcBitIndex <= rcBitIndex - 3'd1;
// end
// rcByte_valid <= (receiving && rcBitIndex == 3'd0 ? 1'b1 : 1'b0);
// Handle the complete incoming byte
if (rcByte_valid) begin
debug_reg[7:4] <= rcByte[3:0];
// First byte: the command
if (`RC_STATE_CMD == rcState || ss_negedge) begin
// Disable writing to the read buffer (will be left on if the prev
// cycle was writing to it)
rcMemWE_reg <= 1'b0;
debug_reg[0] <= 1;
// Decode the SPI command
case (rcByte)
`RC_MODE_GET_STATUS: begin end // no status yet
`RC_MODE_GET_BUFFER: begin rcMode <= `RC_MODE_GET_BUFFER; rcState <= `RC_STATE_SIZE; end
`RC_MODE_PUT_BUFFER: begin rcMode <= `RC_MODE_PUT_BUFFER; rcState <= `RC_STATE_SIZE; end
endcase
// Initialize counters
rcByteCount <= 32'd0;
rcByteSize <= 32'd0;
end
// Record size (in bytes) of payload
if (`RC_STATE_SIZE == rcState) begin
debug_reg[1] <= 1;
case (rcByteCount)
32'd0: begin rcByteSize[31:24] <= rcByte; rcByteCount <= 32'd1; end
32'd1: begin rcByteSize[23:16] <= rcByte; rcByteCount <= 32'd2; end
32'd2: begin rcByteSize[15: 8] <= rcByte; rcByteCount <= 32'd3; end
32'd3: begin
rcByteSize[ 7: 0] <= rcByte;
rcByteCount <= 32'd0;
rcState <= `RC_STATE_PAYLOAD;
rcByteCount <= 32'd0;
if (`RC_MODE_GET_BUFFER == rcMode) begin
// TODO: want reset tx byte addr here probably
end
end
endcase
end
// The payload
if (rcState == `RC_STATE_PAYLOAD) begin
debug_reg[2] <= 1;
case (rcMode)
`RC_MODE_GET_BUFFER: begin
// IGNORE EVERYTHING SO STUFF CAN BE READ OUT
end
`RC_MODE_PUT_BUFFER: begin
//debug_reg[4] <= 1;
rcMemWE_reg <= 1'b1;
rcMemData_reg <= rcByte;
rcMemAddr_reg <= rcByteCount[AddrBits-1:0];
end
endcase
if (rcByteCount == rcByteSize - 1) begin
rcState <= `RC_STATE_CMD;
//debug_reg[5] <= 1;
end else begin
rcByteCount <= rcByteCount + 32'd1;
end
end
end
else begin // not valid byte
if (ss_negedge) begin
rcState <= `RC_STATE_CMD;
end
end
end
//reg [7:0] rcByteReg;
//wire [7:0] rcByte;
//assign rcByte = {rcByteReg[7:1], (SPI_SS == 1'b0 && bitIndex ==
// //
// // Receive (GPU to SPI)
// //
// reg SPI_SS_prev_cycle;
//
// // This is the register backing rcByteId. It is always one cycle
// // behind the true value of rcByteId, which we have to do a little
// // work to get instantaneously correct using wire logic.
// reg [31:0] rcByteIdPrev;
// wire [31:0] rcByteId;
// assign rcByteId = (SPI_SS_prev_cycle == 1 && SPI_SS == 0 ? 32'd0 : 32'd1 + rcByteIdPrev);
//
// // 1 if we're receiving from GPC, 0 if not.
// wire isRecv;
// assign isRecv = ~SPI_SS;
//
// // Bits to Byte aggregator
// reg [2:0] rcBitId;
// reg [7:0] rcByte;
//
//
// reg [31:0] rcSizeBytes;
//
// always @(posedge SPI_CLK) begin
// if (1 == isRecv) begin
// case (rcByteId)
// 0: rcSizeBytes[ 7: 0] <=
// end
//
// // Update registers for next cycle
// SPI_SS_prev_cycle <= SPI_SS;
// rcByteId <= rcByteIdPrev;
// end
*/
endmodule
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