Re: Calculate tuning value for the AD9850 DDS.
Very interesting Henrik.
I have only skimped through the wiki just now and will read properly offline.
I'm currently using one of the cheap ebay modules on a board i designed and a 16f628 to produce a tunable signal generator dds, this is other peoples code in asm though. One other code is a sweep generator/signal generator with decade digit selection by rotary encoder.
I had been trying to do the maths (Nowhere near my capability) to use a rotary encoder in pbp. I did achieve an incrementing counter in pbp with it but got no further to convert to the tuning word.
I was also able to get it to any frequency by inserting the byte sequence for the tuning word into the code. I had all the amateur bands set up as subs and using a pushbutton could step through them.
I wanted to do the dds in pbp so I could add further features such as keypad freq entry, vfo a and vfo b, along with band switching outputs for a ham radio transceiver I'm building.
Below is some sample code. I did move on much further but then got into a jam with ideas.
Regards,
Rob
Code:'**************************************************************** '* Name : DDS Frequency Generator * '* Author : * * '* Date : 10/29/2012 * '* Version : 1.0 * '* Notes : Uses ebay DDS board and rotary encoder * '* : * '**************************************************************** ' ; 16f628a ; __config _CP_OFF&_LVP_OFF&_BODEN_OFF&_PWRTE_OFF&_WDT_OFF&_INTRC_OSC_NOCLKOUT ; ' ' ' ' LCD Display ' ----------- ' ' Define LCD_DREG PORTB ' Port for LCD Data Define LCD_DBIT 0 ' Use lower 4 bits of Port Define LCD_RSREG PORTB ' Port for RegisterSelect (RS) bit Define LCD_RSBIT 6 ' Port Pin for RS bit Define LCD_RWBIT 5 ' Port Pin for RS bit Define LCD_EREG PORTB ' Port for Enable (E) bit Define LCD_EBIT 4 ' Port Pin for E bit Define LCB_BITS 4 ' Using 4-bit bus Define LCD_LINES 2 ' Using 2 line Display Define LCD_COMMANDUS 1200 ' Command Delay (uS) DEFINE LCD_DATAUS 50 ' Data Delay (uS) ' ' Control Buttons/Lines ' --------------------- PB_1 var PortA.4 ' Take this pin low momentarily to change step PB_2 var PortA.3 ' Take this pin low momentarily to change band PB_3 var PortA.2 ' Take this pin low momentarily to RESET EncoderRight var PortA.1 ' rotary encoder pin EncoderLeft var PortA.0 ' rotary encoder pin ddsload var PortB.7 ' dds control word pin ddsdata var PortB.3 ' dds data input ddsclock var PortB.2 ' dds clock input fStep var byte fcount var byte Counter var word CMCON=7 'sets 16f628 comparator pins to digital TRISA=%00011111 'Button & encoder inputs Counter = 0 fcount = 0 fstep = 1 ;start at 1 digit count LOW DDSLOAD 'CONFIGURE DISPLAY pause 1000 LCDOUT $FE,1 ' Clear screen pause 10 lcdout $fe,$c0,dec5 counter ; reset to zero on start ddstart: shiftout ddsdata,ddsclock,0,[ $07,$2B,$02,$0C ] ;start value toggle ddsload pause 100 ;Rotary Encoder Code################################################ mainloop1: if EncoderRight=0 then 'here is switch 2 of the rotary encoder counter=counter+1 gosub up gosub dds gosub lcd endif 'IF PB_1=0 THEN inc_step if EncoderLeft=0 then 'here is switch 1 of the rotary encoder counter = counter-1 gosub down gosub dds gosub lcd endif goto mainloop1 lcd: lcdout $fe,$c0,dec5 counter while (EncoderLeft=0 or EncoderRight=0):pause 10:wend return inc_step: fcount=fcount+1 if fcount=2 then fstep=100 if fcount=1 then fstep=10 fcount=1 return dds: shiftout ddsdata,ddsclock,0,[counter] toggle ddsload return up: counter[0]=counter[0]+1 if counter[0]>99 then counter[0]=0 counter[1]=counter[1]+1 if counter[1]>99 then counter[1]=0 counter[2]=counter[2]+1 if counter[2]>99 then counter[2]=0 counter[3]=counter[3]+1 if counter[3]>99 then counter[3]=0 ;reset to zero endif endif endif endif return down: counter[0]=counter[0]-1 if counter[0]<1 then counter[0]=0 counter[1]=counter[1]-1 if counter[1]<1 then counter[1]=99 counter[2]=counter[2]-1 if counter[2]<1 then counter[2]=99 counter[3]=counter[3]-1 if counter[3]<1 then counter[3]=99 endif endif endif endif return end
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