438 lines
11 KiB
Plaintext
438 lines
11 KiB
Plaintext
m4_changequote(`⟨', `⟩')
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m4_changecom(⟨/*⟩, ⟨*/⟩)
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m4_define(generate_macro, ⟨m4_define(M4_$1, $2)⟩)
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m4_include(control_loop_cmds.m4)
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module control_loop
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#(
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parameter ADC_WID = 18,
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parameter ADC_WID_SIZ = 5,
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parameter ADC_CYCLE_HALF_WAIT = 5,
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parameter ADC_CYCLE_HALF_WAIT_SIZ = 3,
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parameter ADC_POLARITY = 1,
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parameter ADC_PHASE = 0,
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/* The ADC takes maximum 527 ns to capture a value.
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* The clock ticks at 10 ns. Change for different clocks!
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*/
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parameter ADC_CONV_WAIT = 53,
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parameter ADC_CONV_WAIT_SIZ = 6,
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parameter CONSTS_WHOLE = 21,
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parameter CONSTS_FRAC = 43,
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parameter CONSTS_SIZ = 7,
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m4_define(M4_CONSTS_WID, (CONSTS_WHOLE + CONSTS_FRAC))
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parameter DELAY_WID = 16,
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m4_define(M4_DATA_WID, M4_CONSTS_WID)
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parameter READ_DAC_DELAY = 5,
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parameter CYCLE_COUNT_WID = 18,
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parameter DAC_WID = 24,
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/* Analog Devices DACs have a register code in the upper 4 bits.
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* The data follows it. There may be some padding, but the length
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* of a message is always 24 bits.
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*/
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parameter DAC_WID_SIZ = 5,
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parameter DAC_DATA_WID = 20,
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m4_define(M4_E_WID, (DAC_DATA_WID + 1))
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parameter DAC_POLARITY = 0,
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parameter DAC_PHASE = 1,
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parameter DAC_CYCLE_HALF_WAIT = 10,
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parameter DAC_CYCLE_HALF_WAIT_SIZ = 4,
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parameter DAC_SS_WAIT = 5,
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parameter DAC_SS_WAIT_SIZ = 3
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) (
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input clk,
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input rst_L,
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output in_loop,
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output dac_mosi,
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input dac_miso,
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output dac_ss_L,
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output dac_sck,
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input adc_miso,
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output adc_conv_L,
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output adc_sck,
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/* Hacky ad-hoc read-write interface. */
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input [M4_CONTROL_LOOP_CMD_WIDTH-1:0] cmd,
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input [M4_DATA_WID-1:0] word_in,
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output reg [M4_DATA_WID-1:0] word_out,
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input start_cmd,
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output reg finish_cmd
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);
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/************ ADC and DAC modules ***************/
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reg dac_arm;
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reg dac_finished;
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wire dac_ready_to_arm_unused;
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reg [DAC_WID-1:0] to_dac;
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/* verilator lint_off UNUSED */
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wire [DAC_WID-1:0] from_dac;
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/* verilator lint_on UNUSED */
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spi_master_ss #(
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.WID(DAC_WID),
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.WID_LEN(DAC_WID_SIZ),
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.CYCLE_HALF_WAIT(DAC_CYCLE_HALF_WAIT),
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.TIMER_LEN(DAC_CYCLE_HALF_WAIT_SIZ),
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.POLARITY(DAC_POLARITY),
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.PHASE(DAC_PHASE),
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.SS_WAIT(DAC_SS_WAIT),
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.SS_WAIT_TIMER_LEN(DAC_SS_WAIT_SIZ)
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) dac_master (
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.clk(clk),
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.rst_L(rst_L),
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.ready_to_arm(dac_ready_to_arm_unused),
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.mosi(dac_mosi),
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.miso(dac_miso),
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.sck_wire(dac_sck),
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.ss_L(dac_ss_L),
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.finished(dac_finished),
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.arm(dac_arm),
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.from_slave(from_dac),
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.to_slave(to_dac)
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);
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reg adc_arm;
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reg adc_finished;
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wire [ADC_WID-1:0] measured_value;
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wire adc_ready_to_arm_unused;
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localparam [3-1:0] DAC_REGISTER = 3'b001;
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spi_master_ss_no_write #(
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.WID(ADC_WID),
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.WID_LEN(ADC_WID_SIZ),
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.CYCLE_HALF_WAIT(ADC_CYCLE_HALF_WAIT),
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.TIMER_LEN(ADC_CYCLE_HALF_WAIT_SIZ),
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.POLARITY(ADC_POLARITY),
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.PHASE(ADC_PHASE),
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.SS_WAIT(ADC_CONV_WAIT),
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.SS_WAIT_TIMER_LEN(ADC_CONV_WAIT_SIZ)
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) adc_master (
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.clk(clk),
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.ready_to_arm(adc_ready_to_arm_unused),
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.rst_L(rst_L),
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.arm(adc_arm),
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.from_slave(measured_value),
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.miso(adc_miso),
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.sck_wire(adc_sck),
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.ss_L(adc_conv_L),
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.finished(adc_finished)
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);
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/***************** PI Parameters *****************
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* Parameters can be adjusted on the fly by the user. The modifications
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* cannot happen during a calculation, but calculations occur in a matter
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* of milliseconds. Instead, modifications are checked and applied at the
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* start of each iteration (CYCLE_START). Before this, the new values
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* have to be buffered.
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*/
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/* Setpoint: what should the ADC read */
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reg signed [ADC_WID-1:0] setpt = 0;
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reg signed [ADC_WID-1:0] setpt_buffer = 0;
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/* Integral parameter */
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reg signed [M4_CONSTS_WID-1:0] cl_I_reg = 0;
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reg signed [M4_CONSTS_WID-1:0] cl_I_reg_buffer = 0;
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/* Proportional parameter */
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reg signed [M4_CONSTS_WID-1:0] cl_p_reg = 0;
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reg signed [M4_CONSTS_WID-1:0] cl_p_reg_buffer = 0;
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/* Delay parameter (to make the loop run slower) */
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reg [DELAY_WID-1:0] dely = 0;
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reg [DELAY_WID-1:0] dely_buffer = 0;
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/************ Loop Control and Internal Parameters *************/
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reg running = 0;
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reg signed [DAC_DATA_WID-1:0] stored_dac_val = 0;
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reg [CYCLE_COUNT_WID-1:0] last_timer = 0;
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reg [CYCLE_COUNT_WID-1:0] counting_timer = 0;
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reg [M4_CONSTS_WID-1:0] adjval_prev = 0;
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reg signed [M4_E_WID-1:0] err_prev = 0;
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wire signed [M4_E_WID-1:0] e_cur;
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wire signed [M4_CONSTS_WID-1:0] adj_val;
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wire signed [DAC_DATA_WID-1:0] new_dac_val;
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reg arm_math = 0;
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wire math_finished;
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control_loop_math #(
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.CONSTS_WHOLE(CONSTS_WHOLE),
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.CONSTS_FRAC(CONSTS_FRAC),
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.CONSTS_SIZ(CONSTS_SIZ),
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.ADC_WID(ADC_WID),
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.DAC_WID(DAC_DATA_WID),
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.CYCLE_COUNT_WID(CYCLE_COUNT_WID),
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.SEC_PER_CYCLE('b10101011110011000),
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.ADC_TO_DAC({32'b01000001100, 32'b01001001101110100101111000110101})
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) math (
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.clk(clk),
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.rst_L(rst_L),
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.arm(arm_math),
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.finished(math_finished),
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.setpt(setpt),
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.measured(measured_value),
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.cl_P(cl_p_reg),
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.cl_I(cl_I_reg),
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.cycles(last_timer),
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.e_prev(err_prev),
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.adjval_prev(adjval_prev),
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.stored_dac_val(stored_dac_val),
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.new_dac_val(new_dac_val),
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.e_cur(e_cur),
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.adj_val(adj_val)
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);
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/****** State machine
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* ┏━━━━━━━┓
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* ┃ ↓
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* ┗←━INITIATE_READ_FROM_DAC━━←━━━━┓
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* ↓ ┃
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* WAIT_FOR_DAC_READ ┃
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* ↓ ┃
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* WAIT_FOR_DAC_RESPONSE ┃ (on reset)
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* ↓ (when value is read) ┃
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* ┏━━CYCLE_START━━→━━━━━━━━━━━━━━━┛
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* ↑ ↓ (wait time delay)
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* ┃ WAIT_ON_ADC
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* ┃ ↓
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* ┃ WAIT_ON_MUL
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* ┃ ↓
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* ┃ WAIT_ON_DAC
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* ┃ ↓
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* ┗━━━━━━━┛
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****** Outline
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* There are two systems: the read-write interface and the loop.
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* The read-write interface allows another module (i.e. the CPU)
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* to access and change constants. When a constant is changed the
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* loop must reset the values that are preserved between loops
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* (previous adjustment and previous delay).
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*
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* When the loop starts it must find the current value from the
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* DAC and write to it. The value from the DAC is then adjusted
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* with the output of the control loop. Afterwards it does not
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* need to query the DAC for the updated value since it was the one
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* that updated the value in the first place.
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*/
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localparam CYCLE_START = 0;
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localparam WAIT_ON_ADC = 1;
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localparam WAIT_ON_MATH = 2;
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localparam WAIT_ON_DAC = 6;
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localparam INIT_READ_FROM_DAC = 3;
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localparam WAIT_FOR_DAC_READ = 4;
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localparam WAIT_FOR_DAC_RESPONSE = 5;
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localparam STATESIZ = 3;
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reg [STATESIZ-1:0] state = INIT_READ_FROM_DAC;
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reg [DELAY_WID-1:0] timer = 0;
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/**** Timing. ****/
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always @ (posedge clk) begin
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if (!rst_L) begin
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counting_timer <= 0;
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last_timer <= 0;
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end else if (state == CYCLE_START && timer == 0) begin
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counting_timer <= 1;
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last_timer <= counting_timer;
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end else if (running) begin
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counting_timer <= counting_timer + 1;
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end
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end
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/**** Read-Write control interface.
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* `write_control` ensures that writes to the dirty bit do not happen when
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* the main loop is clearing the dirty bit.
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*/
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wire write_control = state == CYCLE_START || !running;
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reg dirty_bit = 0;
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always @ (posedge clk) begin
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if (!rst_L) begin
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dirty_bit <= 0;
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finish_cmd <= 0;
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word_out <= 0;
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end else if (start_cmd && !finish_cmd) begin
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case (cmd)
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M4_CONTROL_LOOP_NOOP:
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finish_cmd <= 1;
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M4_CONTROL_LOOP_NOOP | M4_CONTROL_LOOP_WRITE_BIT:
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finish_cmd <= 1;
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M4_CONTROL_LOOP_STATUS: begin
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word_out[M4_DATA_WID-1:1] <= 0;
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word_out[0] <= running;
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finish_cmd <= 1;
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end
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M4_CONTROL_LOOP_STATUS | M4_CONTROL_LOOP_WRITE_BIT:
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if (write_control) begin
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running <= word_in[0];
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finish_cmd <= 1;
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dirty_bit <= 1;
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end
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M4_CONTROL_LOOP_SETPT: begin
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word_out[M4_DATA_WID-1:ADC_WID] <= 0;
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word_out[ADC_WID-1:0] <= setpt;
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finish_cmd <= 1;
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end
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M4_CONTROL_LOOP_SETPT | M4_CONTROL_LOOP_WRITE_BIT:
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if (write_control) begin
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setpt_buffer <= word_in[ADC_WID-1:0];
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finish_cmd <= 1;
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dirty_bit <= 1;
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end
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M4_CONTROL_LOOP_P: begin
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word_out <= cl_p_reg;
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finish_cmd <= 1;
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end
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M4_CONTROL_LOOP_P | M4_CONTROL_LOOP_WRITE_BIT: begin
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if (write_control) begin
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cl_p_reg_buffer <= word_in;
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finish_cmd <= 1;
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dirty_bit <= 1;
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end
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end
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M4_CONTROL_LOOP_I: begin
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word_out <= cl_I_reg;
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finish_cmd <= 1;
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end
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M4_CONTROL_LOOP_I | M4_CONTROL_LOOP_WRITE_BIT: begin
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if (write_control) begin
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cl_I_reg_buffer <= word_in;
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finish_cmd <= 1;
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dirty_bit <= 1;
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end
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end
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M4_CONTROL_LOOP_DELAY: begin
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word_out[M4_DATA_WID-1:DELAY_WID] <= 0;
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word_out[DELAY_WID-1:0] <= dely;
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finish_cmd <= 1;
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end
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M4_CONTROL_LOOP_DELAY | M4_CONTROL_LOOP_WRITE_BIT: begin
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if (write_control) begin
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dely_buffer <= word_in[DELAY_WID-1:0];
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finish_cmd <= 1;
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dirty_bit <= 1;
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end
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end
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M4_CONTROL_LOOP_ERR: begin
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word_out[M4_DATA_WID-1:M4_E_WID] <= 0;
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word_out[M4_E_WID-1:0] <= err_prev;
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finish_cmd <= 1;
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end
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M4_CONTROL_LOOP_Z: begin
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word_out[M4_DATA_WID-1:DAC_DATA_WID] <= 0;
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word_out[DAC_DATA_WID-1:0] <= stored_dac_val;
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finish_cmd <= 1;
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end
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M4_CONTROL_LOOP_CYCLES: begin
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word_out[M4_DATA_WID-1:CYCLE_COUNT_WID] <= 0;
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word_out[CYCLE_COUNT_WID-1:0] <= last_timer;
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finish_cmd <= 0;
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end
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endcase
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end else if (!start_cmd) begin
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finish_cmd <= 0;
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end
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end
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assign in_loop = state != INIT_READ_FROM_DAC || running;
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always @ (posedge clk) begin
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if (!rst_L) begin
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to_dac <= 0;
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dac_arm <= 0;
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state <= INIT_READ_FROM_DAC;
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timer <= 0;
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stored_dac_val <= 0;
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setpt <= 0;
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dely <= 0;
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cl_I_reg <= 0;
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adjval_prev <= 0;
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err_prev <= 0;
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adc_arm <= 0;
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arm_math <= 0;
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end else case (state)
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INIT_READ_FROM_DAC: begin
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if (running) begin
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to_dac <= {1'b1, DAC_REGISTER, 20'b0};
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dac_arm <= 1;
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state <= WAIT_FOR_DAC_READ;
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end
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end
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WAIT_FOR_DAC_READ: begin
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if (dac_finished) begin
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state <= WAIT_FOR_DAC_RESPONSE;
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dac_arm <= 0;
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timer <= 1;
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end
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end
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WAIT_FOR_DAC_RESPONSE: begin
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if (timer < READ_DAC_DELAY && timer != 0) begin
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timer <= timer + 1;
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end else if (timer == READ_DAC_DELAY) begin
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dac_arm <= 1;
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to_dac <= 24'b0;
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timer <= 0;
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end else if (dac_finished) begin
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state <= CYCLE_START;
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dac_arm <= 0;
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timer <= 0;
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stored_dac_val <= from_dac[DAC_DATA_WID-1:0];
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end
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end
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CYCLE_START: begin
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if (!running) begin
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state <= INIT_READ_FROM_DAC;
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end else if (timer < dely) begin
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timer <= timer + 1;
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end else begin
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/* On change of constants, previous values are invalidated. */
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if (dirty_bit) begin
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setpt <= setpt_buffer;
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dely <= dely_buffer;
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cl_I_reg <= cl_I_reg_buffer;
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cl_p_reg <= cl_p_reg_buffer;
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adjval_prev <= 0;
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err_prev <= 0;
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dirty_bit <= 0;
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end
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state <= WAIT_ON_ADC;
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timer <= 0;
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adc_arm <= 1;
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end
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end
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WAIT_ON_ADC: if (adc_finished) begin
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adc_arm <= 0;
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arm_math <= 1;
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state <= WAIT_ON_MATH;
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end
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WAIT_ON_MATH: if (math_finished) begin
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arm_math <= 0;
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dac_arm <= 1;
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stored_dac_val <= new_dac_val;
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to_dac <= {1'b0, DAC_REGISTER, new_dac_val};
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state <= WAIT_ON_DAC;
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end
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WAIT_ON_DAC: if (dac_finished) begin
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state <= CYCLE_START;
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dac_arm <= 0;
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err_prev <= e_cur;
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adjval_prev <= adj_val;
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end
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endcase
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end
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endmodule
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