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; KCPSM3 Program - Control and calculation for Frequency Generator design using the
; Spartan-3E Starter Kit.
;
; Interfaces with the rotary encoder and LCD display to enable a frequency to be set.
; Converts the BCD frequency value into a binary integer and then performs the high
; precision calculation necessary to derive the control numbers required by the high
; performance Direct Digital Synthesis (DDS) circuit implemented in hardware.
;
; LEDs are connected and used as edit mode indicators.
;
; Substantial comments are included in line with the code below and should be used
; in conjunction with the documentation provided with the complete reference design.
;
;
;
; Ken Chapman - Xilinx Ltd
;
; Version v1.00 - 13th July 2006
;
;**************************************************************************************
;Port definitions
;**************************************************************************************
;
;
;LCD interface ports
;
;The master enable signal is not used by the LCD display itself
;but may be required to confirm that LCD communication is active.
;This is required on the Spartan-3E Starter Kit if the StrataFLASH
;is used because it shares the same data pins and conflicts must be avoided.
;
CONSTANT LCD_output_port, 40 ; LCD character module output data and control
CONSTANT LCD_E, 01 ; active High Enable E - bit0
CONSTANT LCD_RW, 02 ; Read=1 Write=0 RW - bit1
CONSTANT LCD_RS, 04 ; Instruction=0 Data=1 RS - bit2
;CONSTANT LCD_drive, 08 ; Master enable (active High) - bit3
CONSTANT LCD_DB4, 10 ; 4-bit Data DB4 - bit4
CONSTANT LCD_DB5, 20 ; interface Data DB5 - bit5
CONSTANT LCD_DB6, 40 ; Data DB6 - bit6
CONSTANT LCD_DB7, 80 ; Data DB7 - bit7
;
;
CONSTANT LCD_input_port, 01 ; LCD character module input data
CONSTANT LCD_read_DB4, 10 ; 4-bit Data DB4 - bit4
CONSTANT LCD_read_DB5, 20 ; interface Data DB5 - bit5
CONSTANT LCD_read_DB6, 40 ; Data DB6 - bit6
CONSTANT LCD_read_DB7, 80 ; Data DB7 - bit7
;
;
;
;Control of frequency selection values
;
CONSTANT cursor_position, 10 ; Pointer to edit position on LCD
;
; ************************
;
;Constant to define a software delay of 1us. This must be adjusted to reflect the
;clock applied to KCPSM3. Every instruction executes in 2 clock cycles making the
;calculation highly predictable. The '6' in the following equation even allows for
;'CALL delay_1us' instruction in the initiating code.
;
; delay_1us_constant = (clock_rate - 6)/4 Where 'clock_rate' is in MHz
;
;Example: For a 50MHz clock the constant value is (50-6)/4 = 11 (0B Hex).
;For clock rates below 10MHz the value of 1 must be used and the operation will
;become lower than intended.
;
CONSTANT delay_1us_constant, 0B
;
;
;
;ASCII table
;
CONSTANT character_a, 61
CONSTANT character_b, 62
CONSTANT character_c, 63
CONSTANT character_d, 64
CONSTANT character_e, 65
CONSTANT character_f, 66
CONSTANT character_g, 67
CONSTANT character_h, 68
CONSTANT character_i, 69
CONSTANT character_j, 6A
CONSTANT character_k, 6B
CONSTANT character_l, 6C
CONSTANT character_m, 6D
CONSTANT character_n, 6E
CONSTANT character_o, 6F
CONSTANT character_p, 70
CONSTANT character_q, 71
CONSTANT character_r, 72
CONSTANT character_s, 73
CONSTANT character_t, 74
CONSTANT character_u, 75
CONSTANT character_v, 76
CONSTANT character_w, 77
CONSTANT character_x, 78
CONSTANT character_y, 79
CONSTANT character_z, 7A
CONSTANT character_A, 41
CONSTANT character_B, 42
CONSTANT character_C, 43
CONSTANT character_D, 44
CONSTANT character_E, 45
CONSTANT character_F, 46
CONSTANT character_G, 47
CONSTANT character_H, 48
CONSTANT character_I, 49
CONSTANT character_J, 4A
CONSTANT character_K, 4B
CONSTANT character_L, 4C
CONSTANT character_M, 4D
CONSTANT character_N, 4E
CONSTANT character_O, 4F
CONSTANT character_P, 50
CONSTANT character_Q, 51
CONSTANT character_R, 52
CONSTANT character_S, 53
CONSTANT character_T, 54
CONSTANT character_U, 55
CONSTANT character_V, 56
CONSTANT character_W, 57
CONSTANT character_X, 58
CONSTANT character_Y, 59
CONSTANT character_Z, 5A
CONSTANT character_0, 30
CONSTANT character_1, 31
CONSTANT character_2, 32
CONSTANT character_3, 33
CONSTANT character_4, 34
CONSTANT character_5, 35
CONSTANT character_6, 36
CONSTANT character_7, 37
CONSTANT character_8, 38
CONSTANT character_9, 39
CONSTANT character_colon, 3A
CONSTANT character_stop, 2E
CONSTANT character_semi_colon, 3B
CONSTANT character_minus, 2D
CONSTANT character_divide, 2F ;'/'
CONSTANT character_plus, 2B
CONSTANT character_comma, 2C
CONSTANT character_less_than, 3C
CONSTANT character_greater_than, 3E
CONSTANT character_equals, 3D
CONSTANT character_space, 20
CONSTANT character_CR, 0D ;carriage return
CONSTANT character_question, 3F ;'?'
CONSTANT character_dollar, 24
CONSTANT character_exclaim, 21 ;'!'
CONSTANT character_BS, 08 ;Back Space command character
;
;
;
;**************************************************************************************
;Initialise the system
;**************************************************************************************
;
cold_start: CALL LCD_reset ;initialise LCD display
;
;Write 'Frequency Generator' to LCD display and display for 4 seconds
;
LOAD s5, 10 ;Line 1 position 0
CALL LCD_cursor
CALL disp_Frequency
LOAD s5, 22 ;Line 2 position 2
CALL LCD_cursor
CALL disp_Generator
CALL delay_1s ;wait 4 seconds
CALL delay_1s
CALL delay_1s
CALL delay_1s
CALL LCD_clear ;clear screen
;
;
;
CALL delay_1ms
;
;**************************************************************************************
; Main program
;**************************************************************************************
;
; The main program is centred on the task of editing the frequency. It waits until the
; rotary control is used and then makes the appropriate changes. If the actual digit
; digit value is changed then the calculation to drive the DDS is performed each time.
;
; The start state is that of allowing the edit cursor position to be moved. Rotary
; inputs are detected by the interrupt service routine and set a flag bit which the
; main program then uses to adjust the cursor position and pointer to the corresponding
; BCD digit in memory.
;
; A press of the rotary control is detected by polling and used to change to the digit
; editing mode.
;
;
;**************************************************************************************
; Display frequency on top line of the LCD and DDS data on the lower line
;**************************************************************************************
;
; The BCD value should be stored in scratch pad memory in 9 ascending locations
; called BCD_digit0 to BCD_digit8.
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