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lss: Fix I2C master clock period

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Signed-off-by: Alex Forencich <alex@alexforencich.com>
This commit is contained in:
Alex Forencich
2026-03-16 17:13:44 -07:00
parent 89b47d0659
commit fd9cb00a9d
1 changed files with 19 additions and 18 deletions
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37
src/lss/rtl/taxi_i2c_master.sv
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@@ -188,7 +188,6 @@ typedef enum logic [3:0] {
PHY_STATE_READ_BIT_1, PHY_STATE_READ_BIT_1,
PHY_STATE_READ_BIT_2, PHY_STATE_READ_BIT_2,
PHY_STATE_READ_BIT_3, PHY_STATE_READ_BIT_3,
PHY_STATE_READ_BIT_4,
PHY_STATE_STOP_1, PHY_STATE_STOP_1,
PHY_STATE_STOP_2, PHY_STATE_STOP_2,
PHY_STATE_STOP_3 PHY_STATE_STOP_3
@@ -204,6 +203,7 @@ logic phy_release_bus;
logic phy_tx_data; logic phy_tx_data;
logic phy_ready_reg = 1'b0, phy_ready_next;
logic phy_rx_data_reg = 1'b0, phy_rx_data_next; logic phy_rx_data_reg = 1'b0, phy_rx_data_next;
logic [6:0] addr_reg = '0, addr_next; logic [6:0] addr_reg = '0, addr_next;
@@ -310,7 +310,7 @@ always_comb begin
missed_ack_next = 1'b0; missed_ack_next = 1'b0;
// generate delays // generate delays
if (phy_state_reg != PHY_STATE_IDLE && phy_state_reg != PHY_STATE_ACTIVE) begin if (!phy_ready_reg) begin
// wait for phy operation // wait for phy operation
state_next = state_reg; state_next = state_reg;
end else begin end else begin
@@ -592,6 +592,7 @@ end
always_comb begin always_comb begin
phy_state_next = PHY_STATE_IDLE; phy_state_next = PHY_STATE_IDLE;
phy_ready_next = 1'b0;
phy_rx_data_next = phy_rx_data_reg; phy_rx_data_next = phy_rx_data_reg;
delay_count_next = delay_count_reg; delay_count_next = delay_count_reg;
@@ -642,9 +643,11 @@ always_comb begin
case (phy_state_reg) case (phy_state_reg)
PHY_STATE_IDLE: begin PHY_STATE_IDLE: begin
// bus idle - wait for start command // bus idle - wait for start command
phy_ready_next = 1'b1;
sda_o_next = 1'b1; sda_o_next = 1'b1;
scl_o_next = 1'b1; scl_o_next = 1'b1;
if (phy_start_bit) begin if (phy_start_bit && phy_ready_reg) begin
phy_ready_next = 1'b0;
sda_o_next = 1'b0; sda_o_next = 1'b0;
delay_run_next = 1'b1; delay_run_next = 1'b1;
phy_state_next = PHY_STATE_START_1; phy_state_next = PHY_STATE_START_1;
@@ -654,19 +657,24 @@ always_comb begin
end end
PHY_STATE_ACTIVE: begin PHY_STATE_ACTIVE: begin
// bus active // bus active
if (phy_start_bit) begin phy_ready_next = 1'b1;
if (phy_start_bit && phy_ready_reg) begin
phy_ready_next = 1'b0;
sda_o_next = 1'b1; sda_o_next = 1'b1;
delay_run_next = 1'b1; delay_run_next = 1'b1;
phy_state_next = PHY_STATE_REPEATED_START_1; phy_state_next = PHY_STATE_REPEATED_START_1;
end else if (phy_write_bit) begin end else if (phy_write_bit && phy_ready_reg) begin
phy_ready_next = 1'b0;
sda_o_next = phy_tx_data; sda_o_next = phy_tx_data;
delay_run_next = 1'b1; delay_run_next = 1'b1;
phy_state_next = PHY_STATE_WRITE_BIT_1; phy_state_next = PHY_STATE_WRITE_BIT_1;
end else if (phy_read_bit) begin end else if (phy_read_bit && phy_ready_reg) begin
phy_ready_next = 1'b0;
sda_o_next = 1'b1; sda_o_next = 1'b1;
delay_run_next = 1'b1; delay_run_next = 1'b1;
phy_state_next = PHY_STATE_READ_BIT_1; phy_state_next = PHY_STATE_READ_BIT_1;
end else if (phy_stop_bit) begin end else if (phy_stop_bit && phy_ready_reg) begin
phy_ready_next = 1'b0;
sda_o_next = 1'b0; sda_o_next = 1'b0;
delay_run_next = 1'b1; delay_run_next = 1'b1;
phy_state_next = PHY_STATE_STOP_1; phy_state_next = PHY_STATE_STOP_1;
@@ -741,7 +749,6 @@ always_comb begin
// ____ // ____
// scl __/ \__ // scl __/ \__
scl_o_next = 1'b0;
delay_run_next = 1'b1; delay_run_next = 1'b1;
phy_state_next = PHY_STATE_WRITE_BIT_3; phy_state_next = PHY_STATE_WRITE_BIT_3;
end end
@@ -752,6 +759,8 @@ always_comb begin
// ____ // ____
// scl __/ \__ // scl __/ \__
scl_o_next = 1'b0;
delay_run_next = 1'b1;
phy_state_next = PHY_STATE_ACTIVE; phy_state_next = PHY_STATE_ACTIVE;
end end
PHY_STATE_READ_BIT_1: begin PHY_STATE_READ_BIT_1: begin
@@ -786,15 +795,6 @@ always_comb begin
scl_o_next = 1'b0; scl_o_next = 1'b0;
delay_run_next = 1'b1; delay_run_next = 1'b1;
phy_state_next = PHY_STATE_READ_BIT_4;
end
PHY_STATE_READ_BIT_4: begin
// read bit
// ________
// sda X________X
// ____
// scl __/ \__
phy_state_next = PHY_STATE_ACTIVE; phy_state_next = PHY_STATE_ACTIVE;
end end
PHY_STATE_STOP_1: begin PHY_STATE_STOP_1: begin
@@ -841,6 +841,7 @@ always_ff @(posedge clk) begin
state_reg <= state_next; state_reg <= state_next;
phy_state_reg <= phy_state_next; phy_state_reg <= phy_state_next;
phy_ready_reg <= phy_ready_next;
phy_rx_data_reg <= phy_rx_data_next; phy_rx_data_reg <= phy_rx_data_next;
addr_reg <= addr_next; addr_reg <= addr_next;
@@ -875,7 +876,7 @@ always_ff @(posedge clk) begin
last_scl_i_reg <= scl_i_reg; last_scl_i_reg <= scl_i_reg;
last_sda_i_reg <= sda_i_reg; last_sda_i_reg <= sda_i_reg;
busy_reg <= !(state_reg == STATE_IDLE || state_reg == STATE_ACTIVE_WRITE || state_reg == STATE_ACTIVE_READ) || !(phy_state_reg == PHY_STATE_IDLE || phy_state_reg == PHY_STATE_ACTIVE); busy_reg <= !(state_reg == STATE_IDLE || state_reg == STATE_ACTIVE_WRITE || state_reg == STATE_ACTIVE_READ) || !phy_ready_reg;
if (start_bit) begin if (start_bit) begin
bus_active_reg <= 1'b1; bus_active_reg <= 1'b1;