MAMEWorld Forums - News

> An error bigger than the coefficients of the polynom????, it sounds bad :P

Check the percent error graph. It is not that bad. There is going to be measurement errors in the test equipment I used. It's not like I have digital power supplies that will put out accurate 0.1V or less stepped voltages. I have to tweak the knob, get the voltage close to where I want it, then measure. Not to mention the frequency counter I used only does 4 digits. Notice all frequencies I measured above 10000Hz all end in 0. I really need to fix my 100MHz scope with built-in frequency counter.

Remember the chip is not a high tolerance waveform generator. So the errors are well within the tolerance of the chip. When the modulation voltage is below 1V, the frequency can start to jitter, so IMHO, this simulation is close enough. There is no way to make it 100%.

> Edit: why not you try a polynom as in taylor series?? in the form
> a+b*x+c*y+d*x^2+e*x*y+f*y^2+g*x^3+h*x^2*y+i*x*y^2+j*y^3+k*x^4+l*x^3*y+m*x^2*y^2+n*x*y^3+m*y^4+...

I just used what www.zunzun.com recommended and looked closest. Here is the data I used. If you have a better formula, that is not significantly slower, then I will try it out. Right now the new code is a few percent quicker then the old code.

Code:

Range   Fmod    Freq
5	0	890
5	0.21	787
5	0.3	696
5	0.4	635
5	0.5	644
5	0.6	692
5	0.7	736
5	0.8	773
5	0.9	821
5	1	856
5	1.1	905
5	1.2	960
5	1.3	1026
5	1.4	1087
5	1.5	1153
5	1.6	1221
5	1.7	1291
5	1.8	1365
5	1.9	1436
5	2	1515
5	2.1	1589
5	2.2	1665
5	2.3	1742
5	2.4	1819
5	2.5	1893
5	2.6	1977
5	2.7	2055
5	2.8	2140
5	2.9	2221
5	3	2305
5	3.1	2391
5	3.2	2477
5	3.3	2561
5	3.4	2643
5	3.5	2734
5	3.6	2818
5	3.7	2906
5	3.8	2995
5	3.9	3089
5	4	3177
5	4.1	3263
5	4.2	3354
5	4.3	3447
5	4.4	3536
5	4.5	3625
5	4.6	3720
5	4.7	3808
5	4.8	3902
5	4.9	3996
5	5	4087
0	0	1995
0	0.21	2289
0	0.3	2449
0	0.4	2666
0	0.5	2911
0	0.6	3156
0	0.7	3445
0	0.8	3748
0	0.9	4042
0	1	4387
0	1.1	4740
0	1.2	5101
0	1.3	5496
0	1.4	5864
0	1.5	6278
0	1.6	6681
0	1.7	7125
0	1.8	7590
0	1.9	8029
0	2	8480
0	2.1	8984
0	2.2	9485
0	2.3	9985
0	2.4	10450
0	2.5	10960
0	2.6	11480
0	2.7	12010
0	2.8	12550
0	2.9	13070
0	3	13610
0	3.1	14150
0	3.2	14690
0	3.3	15220
0	3.4	15720
0	3.5	16280
0	3.6	16780
0	3.7	17300
0	3.8	17800
0	3.9	18340
0	4	18850
0	4.1	19340
0	4.2	19840
0	4.3	20340
0	4.4	20810
0	4.5	21300
0	4.6	21780
0	4.7	22230
0	4.8	22710
0	4.9	23160
0	5	23610

Do not p-mail me for help compiling my updates, ask on the board.
Do not request sound for your favorite game. I work on whatever, when I get around to it.
If you have schematics for discrete sound games not easily found on the net, I would be interested.