Hi! I find a serious proble that the value of coefficient which generate from the SigmaStudio is different from the equation of helping document!
For example,a 1st order filter,We set for 1000HZ frequency,gain of 0dB and as the lowpass filter,I got the coefficient are respectively 0.121918916702271 ,0, 0.878081083297729
In helping a document
The General 1stOrder block has two algorithms options.
Common variables:
ω0 = 2*pi*f0/Fs
gainLinear = 10^(gain/20)
Lowpass
f0=1000Hz;Fs=48000Hz;gain=0;
So w0=2*pi*1000/48000=0.130899693899574718269276;gainlinear=10^(0/20)=1;
a1=2.7^w0=2.7^0.130899693899574718269276=1.1388470067969598079945487283746;
a1=1/a1=0.87808107149750427306800276251186;
b0= gainLinear * (1.0  1/a1)=0.1219189285024957269319972374; b1=0;
In the actual implementation on the DSP, when the coefficients are stored in parameter RAM, a1 needs to be inverted. This is done in software, automatically, before the parameters are written to memory.
For example,a general 2nd order filter,we set for 1000Hz frequency, gain of 0dB,Q of 1.41, and as the lowpass filter,i got the coefficient are respectively EQ1940Single10B1=0.00408828258514404;
EQ1940Single11B1=0.00817668437957764;
EQ1940Single12B1=0.00408828258514404;
EQ1940Single11A1=1.8951700925827;
EQ1940Single12A1=0.911523461341858;
But in helping a docment:
Lowpass
ω0 = 2*pi*f0/Fs
gainLinear = 10^(gain/20)
Transfer Function 

Coefficients  alpha = sin(ω0)/(2*Q)
a0 = 1 + alpha a1 = 2*cos(ω0) a2 = 1  alpha b0 = (1  cos(ω0)) * gainLinear / 2 b1 = 1  cos(ω0) * gainLinear b2 = (1  cos(ω0)) * gainLinear / 2 
For all of the above filters, the coefficients are divided by a0, normalizing them and making a0 = 1 so that only 5 coefficients must be stored. In the actual implementation on the DSP, when the coefficients are stored in parameter RAM, a1 and a2 need to be inverted. This is done automatically, in software, before the parameters are written to memory.
Among them
gain=0dB;fs=1000Hz;Fs=48000Hz; Q=1.41;
So w0=2*pi*1000/48000=0.130899693899574718269276; gainlinear=1;
alpha=sin(0.130899693899574718269276)/(2*1.41)=0.0008101520074285072310965239913;
a0=1+0.0008101520074285072310965239913=1.0008101520074285072310965239913;
a1=2*cos(0.130899693899574718269276)=1.9999947804650706869450798840089; 1/a1=0.50000130488713778026095773346491;
a2=10.0008101520074285072310965239913=0.999189847992571492768903476009;1/a2=1.0008108088858750397659847761385;
b0=(1cos(0.130899693899574718269276))/2=0.0000013048837323282637300289978;
b1=2*b0=0.000002609767464656527460057994;b2=b0;
Easily we could find the difference between the coefficient values generated by SigmaStudio, and those you calculate accoeding to the equation of helping document.
Egerly look forward to your reply.thanks very much!
Hi Leiming,
I have requested a complete list of the filter parameter calculations from the software team, but it may take a few days before I receive the information. Once I have it, I will post it here.