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Re: NCO Calculator
NCOa.zip
I'm a bit new to this whole PC programming thing. I spent some time with the NCO Calculator and realized it really needed a bit of refinement. Attached is a cleaner version. Old one still works, but the new one has a few filters that make it more user friendly. The new one expands the Fosc range to include more options.
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Re: NCO Calculator
Using Mr. E-Calc, I wanted to calculate values for a PWM frequency using LFINTOSC, which is 32 kHz. I entered 0.031 where it asks for Fosc (MHz) and wouldn't you know it, IT WORKED! Got me thinking about the NCO Calc. I had limited Fosc to 1 MHz on the low end. This updated Version 1.02 lowered the minimum to 1 kHz (0.001 in the Fosc box).
Nco Calc1_02.zip
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Re: NCO Calculator
Hi mpgmike (and gang):
I like your NCO Calculator app'. Thank you.
My calculation results are slightly different from those produced by your NCO Calculator. Would you or another forum member have time to help me figure out the problem with my calculations, please?
I designed a ClockGen IC for a retro 65C02 project a couple years ago using an 8 pin 16F18313 (listing attached below). I used a 32-MHz clock and I used the NCO to generate a 1.8432 MHz clock for an ACIA chip on that project. My NCO calculations were;
Resolution = 32000000 / 2^20 / 2 = 15.2587890625-Hz
Phase_Inc = 1843200 / 15.2587890625 = 120795.9552
Rounding up the phase increment value to 120796 I get the following frequency output;
Freq_output = 120796 * 15.2587890625 = 1843200.68359375-Hz
Freq_error = 1843200.68359375 / 1843200 - 1 = ~0.00004%
Since my phase increment and output frequency values are slightly different than those of the NCO Calculator, I'm wondering if I messed up on my calculations.
Help appreciated. TIA...
Cheerful regards, Mike
Code:;****************************************************************** ; * ; Project: 65C02_Clock * ; File: 16F18313_Clock.asm * ; Author: Mike McLaren, K8LH * ; (C)2016: Micro Application Consultants * ; : All Rights Reserved * ; Date: 04-Apr-2016 * ; * ; 16F18313 Clock-Gen + Econo-Reset for 65C02 (8-MHz crystal) * ; produces a 1, 2, 4, or 8 MHz CPU clock and an ACIA clock. * ; * ; IDE: MPLABX v3.05 * ; Lang: MPASM v5.62 (absolute addressing mode) * ; * ;****************************************************************** #include <p16F18313.INC> errorlevel -302,-311 ; suppress bank warnings list st=off ; symbol table off radix dec ;~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ ; config settings ~ ;~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ __CONFIG _CONFIG1, _FEXTOSC_HS & _FCMEN_OFF ; ; CLKOUTEN_OFF default ; CSWEN_ON default ; __CONFIG _CONFIG2, _WDTE_OFF & _PPS1WAY_OFF ; ; MCLRE_ON default ; PWRTE_OFF default ; LPBOREN_OFF default ; BOREN_ON default ; BOREN_LOW default ; STVREN_ON default ; DEBUG_OFF default ; __CONFIG _CONFIG3, _LVP_OFF ; ; WRT_OFF default ; __CONFIG _CONFIG4, _CP_OFF & _CPD_OFF ;~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ ; variables ~ ;~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ cblock 0x70 ; common RAM available any bank delayhi ; DelayCy() subsystem variable endc ;~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ ; constants ~ ;~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ ; ; assign clock and reset pins (RA0..RA2 inclusive). ; PHI0_clk equ RA0 ; bit index for RA0 (0) ACIA_clk equ RA1 ; bit index for RA1 (1) RESB_out equ RA2 ; bit index for RA2 (2) ; ; associate to "Peripheral Pin Select" output registers. ; PHI0_PPS equ RA0PPS+PHI0_clk ; equ RA0PPS ACIA_PPS equ RA0PPS+ACIA_clk ; equ RA1PPS RESB_PPS equ RA0PPS+RESB_out ; equ RA2PPS ; ; set 'CLKR_div' constant for desired 65C02 clock frequency. ; ; 6 -> 0.5-MHz (Fosc / 64) ; 5 -> 1.0-MHz (Fosc / 32) ; 4 -> 2.0-MHz (Fosc / 16) ; 3 -> 4.0-MHz (Fosc / 8) ; 2 -> 8.0-MHz (Fosc / 4) ; 1 -> 16.0-MHz (Fosc / 2) ; CLKR_div equ 4 ; 2.0-MHz PHI0 CPU clock ; ; set 'NCO1_inc' constant for desired ACIA clock output. ; ; 2517 -> 38400-Hz ( 2400 * 16) @ 0.01659% ; 5033 -> 76800-Hz ( 4800 * 16) @ 0.00327% ; 10066 -> 153600-Hz ( 9600 * 16) @ 0.00327% ; 20133 -> 307200-Hz ( 19200 * 16) @ 0.00169% ; 40265 -> 614400-Hz ( 38400 * 16) @ 0.00079% ; 60398 -> 921600-Hz ( 57600 * 16) @ 0.00004% ; 120796 -> 1843200-Hz (115200 * 16) @ 0.00004% ; 241592 -> 3686400-Hz (230400 * 16) @ 0.00004% ; NCO1_inc equ 120796 ; 1.8432-MHz (115200 * 16) ;~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ ; K8LH DelayCy() subsystem macro generates four instructions ~ ;~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ radix dec clock equ 32 ; 4, 8, 12, 16, 20 (MHz), etc. usecs equ clock/4 ; cycles/microsecond multiplier msecs equ usecs*1000 ; cycles/millisecond multiplier dloop equ 5 ; loop size, 5 to ??? cycles ; ; -- loop -- -- delay range -- -- memory overhead ---------- ; 5-cyc loop, 11..327690 cycles, 9 words (+4 each macro call) ; 6-cyc loop, 11..393226 cycles, 10 words (+4 each macro call) ; 7-cyc loop, 11..458762 cycles, 11 words (+4 each macro call) ; 8-cyc loop, 11..524298 cycles, 12 words (+4 each macro call) ; 9-cyc loop, 11..589834 cycles, 13 words (+4 each macro call) ; DelayCy macro cycles ; range, see above if (cycles<11)|(cycles>(dloop*65536+10)) error " DelayCy range error " else movlw high((cycles-11)/dloop)+1 movwf delayhi movlw low ((cycles-11)/dloop) call uLoop-((cycles-11)%dloop) endif endm ;~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ ; reset vector ~ ;~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ org 0x0000 v_reset bra setup ; |00 ;~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ ; interrupt vector ~ ;~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ org 0x0004 v_int retfie ; |?? ;~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ ; main setup ~ ;~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ setup ; ; turn off analog functions (all I/O will be digital). ; banksel ANSELA ; bank 03 |03 clrf ANSELA ; analog off, digital I/O |03 ; ; setup data direction for 'output' pins (default 'input'). ; banksel TRISA ; bank 01 |01 bcf TRISA,PHI0_clk ; set phi0 clock pin as output |01 bcf TRISA,ACIA_clk ; set acia clock pin as output |01 bcf TRISA,RESB_out ; set resb reset pin as output |01 ; ; clear RESB pin output latch (hold the 65C02 in reset). ; banksel LATA ; bank 02 |02 bcf LATA,RESB_out ; RESB_out = '0' |02 ; ; setup Fosc for 32-MHz (external 8-MHz crystal and 4xPLL). ; banksel OSCCON1 ; bank 18 |18 movlw b'00010000' ; -001---- NOSC[2:0], Ext 4xPLL |18 ; ----0000 NDIV[3:0], Clk Div 1 |18 movwf OSCCON1 ; 8-MHz Xtal & 4xPLL -> 32-MHz |18 stable btfss OSCCON3,ORDY ; OSC stable? yes, skip, else |18 bra stable ; loop (wait until OSC stable) |18 ; ; assign PHI0_clk pin (RA0) and ACIA_clk pin (RA1) resources ; via 'Peripheral Pin Select'. ; banksel PPSLOCK ; bank 28 |28 movlw 0x55 ; PPS unlock sequence |28 movwf PPSLOCK ; " |28 movlw 0xAA ; " |28 movwf PPSLOCK ; " |28 bcf PPSLOCK,PPSLOCKED ; " |28 banksel PHI0_PPS ; bank 29 |29 movlw b'00011110' ; assign CLKR (Ref Clock) output |29 movwf PHI0_PPS ; to the PHI0 clock pin (RA0) |29 movlw b'00011101' ; assign NCO module output to |29 movwf ACIA_PPS ; the ACIA clock pin (RA1) |29 banksel PPSLOCK ; bank 28 |28 bsf PPSLOCK,PPSLOCKED ; all done, lock it up |28 ; ; setup CLKR (Reference Clock) module for PHI0 CPU Clock. ; banksel CLKRCON ; bank 07 |07 movlw 0x10|CLKR_div ; 50% duty cycle & divider bits |07 movwf CLKRCON ; prep 1, 2, 4, or 8-MHz output |07 bsf CLKRCON,CLKREN ; enable Reference Clock output |07 ; ; setup NCO to generate the ACIA clock. ; banksel NCO1CON ; bank 08 |08 ; bcf NCO1CON,N1PFM ; fixed duty cycle mode (default) |08 movlw b'00000001' ; N1CKS<1:0> = '01' = Fosc |08 movwf NCO1CLK ; set NCO clock source |08 clrf NCO1ACCL ; clear 20-bit phase accumulator |08 clrf NCO1ACCH ; " |08 clrf NCO1ACCU ; " |08 movlw upper(NCO1_inc) ; " |08 movwf NCO1INCU ; " |08 movlw high(NCO1_inc) ; " |08 movwf NCO1INCH ; " |08 movlw low(NCO1_inc) ; setup 20-bit phase increment |08 movwf NCO1INCL ; " |08 bsf NCO1CON,N1EN ; enable NCO module output |08 ; ; complete the 65C02 reset cycle. ; DelayCy(20*msecs) ; wait ~20-msecs |08 banksel LATA ; bank 02 |02 bsf LATA,RESB_out ; release 65C02 from reset |02 ;~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ ; main loop ~ ;~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ loop bra loop ; loop forever (until reset) |02 ;~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ ; K8LH DelayCy() subsystem 16-bit 'uLoop' timing subroutine ~ ;~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ a = dloop-1 while a > 0 nop ; (cycles-11)%dloop entry points |?? a -= 1 endw uLoop addlw -1 ; subtract 'dloop' loop time |?? skpc ; borrow? no, skip, else |?? decfsz delayhi,F ; done? yes, skip, else |?? bra uLoop-dloop+5 ; do another loop |?? return ; |?? ;~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ end
Last edited by Mike, K8LH; - 6th May 2018 at 17:59.
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Re: NCO Calculator
In the NCO Calc I entered:
Fosc = 32 MHz
Frequency = 1,843,200 (didn't use commas in the NCO Calc, added for clarity here)
What I got in return was:
NCO Decimal = 120795.84
NCO HEX = 1D7DC
Result Rounded Up = 1,843,217.7002
Result Rounded Down = 1,843,202.4414
Our results aren't that much different. The project I developed the NCO Calc for is reading within < 0.02 Hz different than calculated with the NCO Calc. Not sure what you got.
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Re: NCO Calculator
Hi mpgmike. Thanks for the reply.
Those are the same numbers I got from NCO Calculator. May I ask how you produced some of those numbers, if you have time, please? I'm concerned that I'm using the wrong formulas for the calculated output frequency and error.
What formula did you use to produce the 120795.84 phase increment value? My result was 120795.9552 which is ever so slightly different (formula in my previous post).
What formula do you use to produce "Result Rounded Up" and "Result Rounded Down" values? Are those supposed to be the frequency output when you round the phase increment value to integer values of 120795 or 120796? I'm concerned about my calculations as I came up with an output frequency of 1843200.68359375-Hz (~0.00004% off) using 120796 for the phase increment value.
If I'm using the wrong calculations I'd like to fix them and update the frequency error comments in my project.
Thank you for your time and kind consideration.
Cheerful regards, Mike, K8LH
Last edited by Mike, K8LH; - 9th May 2018 at 01:48.
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Re: NCO Calculator
The basic formula reduces down to:
NCO Value = (Frequency * 2,097,150) / Fosc
Building the NCO Calc in Visual Basic, the behind-the-scenes math was:
NcoDec = (Freq * 2.09715) / Fosc
NcoDecR = Math.Round(NcoDec, 3)
FreqDn = Math.Round(((NcoInt * Fosc) / 2.09715), 4)
FreqUp = Math.Round(((NcoInt1 * Fosc) / 2.09715), 4)
There's a bit of other code in there, but that's the math.
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Re: NCO Calculator
I think I found the problem... 2^21 equals 2097152, not 2097150. When I plug the 2097152 value into your formulas the phase increment and output frequency results match my calculations.
Thank you so much for helping me verify my calculations are correct.
Cheerful regards, Mike, K8LH
Fosc = 32000000
Freq = 1843200
NCO Decimal = 120795.9552
NCO HEX = 1D7DC
Result Rounded Up = 1843200.68359375
Result Rounded Down = 1843185.4248046875
Resolution = 15.2587890625-Hz
Last edited by Mike, K8LH; - 9th May 2018 at 04:15.
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