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FPGA: SPI-master improvements

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- Changed FSM states to localparams
- Added localparam for SPI clock divisor
- Added internal signal for divisor reached
- Improved comments to clarify code
- Fixed some minor textual nits

Signed-off-by: Joachim Strömbergson <joachim@assured.se>
This commit is contained in:
Joachim Strömbergson 2024-06-18 08:29:08 +02:00 committed by dehanj
parent 120956b835
commit 8ce07683f8
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GPG Key ID: 3707A9DBF4BB8F1A
1 changed files with 30 additions and 14 deletions
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42
hw/application_fpga/core/tk1/rtl/tk1_spi_master.v
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@ -45,12 +45,14 @@ module tk1_spi_master(
//----------------------------------------------------------------
// Internal constant and parameter definitions.
//----------------------------------------------------------------
parameter CTRL_IDLE = 3'h0;
parameter CTRL_POS_FLANK = 3'h1;
parameter CTRL_WAIT_POS = 3'h2;
parameter CTRL_NEG_FLANK = 3'h3;
parameter CTRL_WAIT_NEG = 3'h4;
parameter CTRL_NEXT = 3'h5;
localparam CTRL_IDLE = 3'h0;
localparam CTRL_POS_FLANK = 3'h1;
localparam CTRL_WAIT_POS = 3'h2;
localparam CTRL_NEG_FLANK = 3'h3;
localparam CTRL_WAIT_NEG = 3'h4;
localparam CTRL_NEXT = 3'h5;
localparam SPI_CLK_CYCLES = 4'hf;
//----------------------------------------------------------------
@ -93,6 +95,12 @@ module tk1_spi_master(
reg spi_ctrl_we;
//----------------------------------------------------------------
// Wires.
//----------------------------------------------------------------
reg spi_clk_cycles_reached;
//----------------------------------------------------------------
// Concurrent connectivity for ports etc.
//----------------------------------------------------------------
@ -156,17 +164,24 @@ module tk1_spi_master(
//----------------------------------------------------------------
// clk_ctr
// cpi_clk_ctr
//
// Continuously running clock cycle counter that can be
// reset to zero.
// Resettable clock cycle counter used to generate the SPI clock.
//----------------------------------------------------------------
always @*
begin : clk_ctr
begin : spi_clk_ctr
spi_clk_cycles_reached = 1'h0;
if (spi_clk_ctr_reg == SPI_CLK_CYCLES) begin
spi_clk_cycles_reached = 1'h1;
end
else begin
spi_clk_cycles_reached = 1'h0;
end
if (spi_clk_ctr_rst) begin
spi_clk_ctr_new = 4'h0;
end
else begin
spi_clk_ctr_new = spi_clk_ctr_reg + 1'h1;
end
@ -195,6 +210,7 @@ module tk1_spi_master(
//----------------------------------------------------------------
// spi_tx_data_logic
//
// Logic for the tx_data shift register.
// Either load or shift the data register.
//----------------------------------------------------------------
@ -279,7 +295,7 @@ module tk1_spi_master(
end
CTRL_WAIT_POS: begin
if (spi_clk_ctr_reg == 4'hf) begin
if (spi_clk_cycles_reached) begin
spi_ctrl_new = CTRL_NEG_FLANK;
spi_ctrl_we = 1'h1;
end
@ -294,7 +310,7 @@ module tk1_spi_master(
end
CTRL_WAIT_NEG: begin
if (spi_clk_ctr_reg == 4'hf) begin
if (spi_clk_cycles_reached) begin
spi_ctrl_new = CTRL_NEXT;
spi_ctrl_we = 1'h1;
end