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Diffstat (limited to 'src/rtl/fpga_mkm_spi_slave.v')
-rw-r--r--src/rtl/fpga_mkm_spi_slave.v234
1 files changed, 126 insertions, 108 deletions
diff --git a/src/rtl/fpga_mkm_spi_slave.v b/src/rtl/fpga_mkm_spi_slave.v
index 473d37d..1449af2 100644
--- a/src/rtl/fpga_mkm_spi_slave.v
+++ b/src/rtl/fpga_mkm_spi_slave.v
@@ -48,91 +48,78 @@
//======================================================================
module fpga_mkm_spi_slave(
- input wire clk,
+ input wire clk,
- input wire ss,
- input wire sclk,
- input wire mosi,
- output wire miso,
+ input wire ss,
+ input wire sclk,
+ input wire mosi,
+ output wire miso,
- output wire rx_byte_available,
- output wire rx_byte_ack,
+ output wire spi_active,
+ output wire rx_byte_available,
output wire [7 : 0] rx_byte,
- input wire tx_byte_available,
- output wire tx_byte_ack,
- output wire tx_byte_error,
- input wire [7 : 0] tx_byte
+ input wire tx_byte_load,
+ input wire [7 : 0] tx_byte
);
//----------------------------------------------------------------
// Internal constant and parameter definitions.
//----------------------------------------------------------------
- localparam CTRL_IDLE = 3'h0;
+ localparam CTRL_IDLE = 3'h0;
+ localparam CTRL_SELECTED = 3'h1;
+ localparam CTRL_POS_EDGE = 3'h2;
+ localparam CTRL_NEG_EDGE = 3'h3;
//----------------------------------------------------------------
// Registers including update variables and write enable.
//----------------------------------------------------------------
- reg ss_sample0_reg;
- reg ss_sample1_reg;
- reg ss_reg;
+ reg ss_sample0_reg;
+ reg ss_sample1_reg;
+ reg ss_reg;
- reg sclk_sample0_reg;
- reg sclk_sample1_reg;
- reg sclk_reg;
+ reg sclk_sample0_reg;
+ reg sclk_sample1_reg;
+ reg sclk_reg;
- reg mosi_sample0_reg;
- reg mosi_sample1_reg;
- reg mosi_reg;
+ reg mosi_sample0_reg;
+ reg mosi_sample1_reg;
+ reg mosi_reg;
reg [7 : 0] rx_byte_reg = 8'h0;
reg [7 : 0] rx_byte_new;
- reg rx_byte_we;
-
- reg [2 : 0] rx_bit_ctr_reg = 3'h0;
- reg [2 : 0] rx_bit_ctr_new;
- reg rx_bit_ctr_we;
- reg rx_bit_ctr_rst;
- reg rx_bit_ctr_inc;
-
- reg rx_byte_available_reg = 1'h0;
- reg rx_byte_available_new;
- reg rx_byte_available_we;
+ reg rx_byte_next;
reg [7 : 0] tx_byte_reg = 8'h0;
reg [7 : 0] tx_byte_new;
reg tx_byte_we;
- reg tx_byte_load;
- reg tx_byte_loadz;
reg tx_byte_next;
+ reg tx_byte_loadz;
- reg [2 : 0] tx_bit_ctr_reg = 3'h0;
- reg [2 : 0] tx_bit_ctr_new;
- reg tx_bit_ctr_we;
- reg tx_bit_ctr_rst;
- reg tx_bit_ctr_inc;
-
- reg tx_byte_ack_reg = 1'h0;
- reg tx_byte_ack_new;
+ reg [2 : 0] bit_ctr_reg = 3'h0;
+ reg [2 : 0] bit_ctr_new;
+ reg bit_ctr_we;
+ reg bit_ctr_rst;
+ reg bit_ctr_inc;
- reg tx_byte_error_reg = 1'h0;
- reg tx_byte_error_new;
+ reg spi_active_reg = 1'h0;
+ reg spi_active_new;
+ reg spi_active_we;
- reg [2 : 0] spi_slave_ctrl_reg = CTRL_IDLE;
- reg [2 : 0] spi_slave_ctrl_new;
- reg spi_slave_ctrl_we;
+ reg [2 : 0] spi_slave_ctrl_reg = CTRL_IDLE;
+ reg [2 : 0] spi_slave_ctrl_new;
+ reg spi_slave_ctrl_we;
//----------------------------------------------------------------
// Concurrent connectivity for ports etc.
//----------------------------------------------------------------
assign miso = tx_byte_reg[7];
- assign rx_byte_available = rx_byte_available_reg;
+ assign rx_byte_available = (bit_ctr_reg == 3'h7);
assign rx_byte = rx_byte_reg;
- assign tx_byte_ack = tx_byte_ack_reg;
- assign tx_byte_error = tx_byte_error_reg;
+ assign spi_active = spi_active_reg;
//----------------------------------------------------------------
@@ -152,23 +139,17 @@ module fpga_mkm_spi_slave(
mosi_sample1_reg <= mosi_sample0_reg;
mosi_reg <= mosi_sample1_reg;
- tx_byte_ack_reg <= tx_byte_ack_new;
- tx_byte_error_reg <= tx_byte_error_new;
-
- if (rx_byte_we)
+ if (rx_byte_next)
rx_byte_reg <= {rx_byte_reg[6 : 0], mosi_reg};
- if (rx_bit_ctr_we)
- rx_bit_ctr_reg <= rx_bit_ctr_new;
-
- if (rx_byte_available_we)
- rx_byte_available_reg <= rx_byte_available_new;
+ if (bit_ctr_we)
+ bit_ctr_reg <= bit_ctr_new;
if (tx_byte_we)
tx_byte_reg <= tx_byte_new;
- if (tx_bit_ctr_we)
- tx_bit_ctr_reg <= tx_bit_ctr_new;
+ if (spi_active_we)
+ spi_active_reg <= spi_active_new;
if (spi_slave_ctrl_we)
spi_slave_ctrl_reg <= spi_slave_ctrl_new;
@@ -181,7 +162,7 @@ module fpga_mkm_spi_slave(
// set the next bit to transmit.
//----------------------------------------------------------------
always @*
- begin : tx_byt_logic
+ begin : tx_byte_logic
tx_byte_new = 8'h0;
tx_byte_we = 1'h0;
@@ -199,52 +180,30 @@ module fpga_mkm_spi_slave(
if (tx_byte_next)
begin
- tx_byte_new = {tx_byte_reg[6 : 0], 1'h0]};
+ tx_byte_new = {tx_byte_reg[6 : 0], 1'h0};
tx_byte_we = 1'h1;
end
end
//----------------------------------------------------------------
- // rx_bit_ctr
- //----------------------------------------------------------------
- always @*
- begin : rx_bit_ctr
- rx_bit_ctr_new = 3'h0;
- rx_bit_ctr_we = 1'h0;
-
- if (rx_bit_ctr_rst)
- begin
- rx_bit_ctr_new = 3'h0;
- rx_bit_ctr_we = 1'h1;
- end
-
- if (rx_bit_ctr_inc)
- begin
- rx_bit_ctr_new = rx_bit_ctr_reg + 1'h1;
- rx_bit_ctr_we = 1'h0;
- end
- end
-
-
- //----------------------------------------------------------------
- // tx_bit_ctr
+ // bit_ctr
//----------------------------------------------------------------
always @*
- begin : tx_bit_ctr
- tx_bit_ctr_new = 3'h0;
- tx_bit_ctr_we = 1'h0;
+ begin : bit_ctr
+ bit_ctr_new = 3'h0;
+ bit_ctr_we = 1'h0;
- if (tx_bit_ctr_rst)
+ if (bit_ctr_rst)
begin
- tx_bit_ctr_new = 3'h0;
- tx_bit_ctr_we = 1'h1;
+ bit_ctr_new = 3'h0;
+ bit_ctr_we = 1'h1;
end
- if (tx_bit_ctr_inc)
+ if (bit_ctr_inc)
begin
- tx_bit_ctr_new = tx_bit_ctr_reg + 1'h1;
- tx_bit_ctr_we = 1'h0;
+ bit_ctr_new = bit_ctr_reg + 1'h1;
+ bit_ctr_we = 1'h1;
end
end
@@ -254,22 +213,81 @@ module fpga_mkm_spi_slave(
//----------------------------------------------------------------
always @*
begin : spi_slave_ctrl_fsm
- rx_bit_ctr_rst = 1'h0;
- rx_bit_ctr_inc = 1'h0;
- tx_bit_ctr_rst = 1'h0;
- tx_bit_ctr_inc = 1'h0;
- tx_byte_load = 1'h0;
- tx_byte_loadz = 1'h0;
- tx_byte_next = 1'h0;
- tx_byte_ack_new = 1'h0;
- tx_byte_error_new = 1'h0;
- rx_byte_we = 1'h0;
-
+ bit_ctr_rst = 1'h0;
+ bit_ctr_inc = 1'h0;
+ rx_byte_next = 1'h0;
+ tx_byte_loadz = 1'h0;
+ tx_byte_next = 1'h0;
+ spi_active_new = 1'h0;
+ spi_active_we = 1'h0;
+ spi_slave_ctrl_new = CTRL_IDLE;
+ spi_slave_ctrl_we = 1'h0;
case (spi_slave_ctrl_reg)
-
+ CTRL_IDLE:
+ begin
+ if (ss_reg == 0)
+ begin
+ spi_slave_ctrl_new = CTRL_SELECTED;
+ spi_slave_ctrl_we = 1'h1;
+ end
+ end
+
+
+ CTRL_SELECTED:
+ begin
+ bit_ctr_rst = 1'h1;
+ tx_byte_loadz = 1'h1;
+ spi_active_new = 1'h1;
+ spi_active_we = 1'h1;
+ spi_slave_ctrl_new = CTRL_POS_EDGE;
+ spi_slave_ctrl_we = 1'h1;
+ end
+
+
+ CTRL_POS_EDGE:
+ begin
+ if (ss_reg == 0)
+ begin
+ if ((sclk_sample1_reg == 1'h1) && (sclk_reg == 1'h0))
+ begin
+ rx_byte_next = 1'h1;
+ tx_byte_next = 1'h1;
+ bit_ctr_inc = 1'h1;
+ spi_slave_ctrl_new = CTRL_NEG_EDGE;
+ spi_slave_ctrl_we = 1'h1;
+ end
+ end
+ else
+ begin
+ spi_active_new = 1'h0;
+ spi_active_we = 1'h1;
+ spi_slave_ctrl_new = CTRL_IDLE;
+ spi_slave_ctrl_we = 1'h1;
+ end
+ end
+
+
+ CTRL_NEG_EDGE:
+ begin
+ if (ss_reg == 0)
+ begin
+ if ((sclk_sample1_reg == 1'h0) && (sclk_reg == 1'h1))
+ begin
+ spi_slave_ctrl_new = CTRL_POS_EDGE;
+ spi_slave_ctrl_we = 1'h1;
+ end
+ end
+ else
+ begin
+ spi_active_new = 1'h0;
+ spi_active_we = 1'h1;
+ spi_slave_ctrl_new = CTRL_IDLE;
+ spi_slave_ctrl_we = 1'h1;
+ end
+ end
endcase // case (spi_slave_ctrl_reg)
- end
+ end // block: spi_slave_ctrl_fsm
endmodule // fpga_mkm_spi_slave
generated by cgit v1.2.3 (git 2.25.1) at 2024-05-02 07:15:21 +0000