<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=us-ascii">
<style type="text/css" style="display:none;"> P {margin-top:0;margin-bottom:0;} </style>
</head>
<body dir="ltr">
<div style="font-family: Calibri, Arial, Helvetica, sans-serif; font-size: 12pt; color: rgb(0, 0, 0); background-color: rgb(255, 255, 255);" class="elementToProof">
Don't you mess up the effects of any log element that way ?</div>
<div style="font-family: Calibri, Arial, Helvetica, sans-serif; font-size: 12pt; color: rgb(0, 0, 0); background-color: rgb(255, 255, 255);" class="elementToProof">
<br>
</div>
<div style="font-family: Calibri, Arial, Helvetica, sans-serif; font-size: 12pt; color: rgb(0, 0, 0); background-color: rgb(255, 255, 255);" class="elementToProof">
But definitely works for a linear synth. My first microcontroller based synth (a Z80) in the early 80s used PWM for VCFs and VCAs.<br>
</div>
<div id="appendonsend"></div>
<hr style="display:inline-block;width:98%" tabindex="-1">
<div id="divRplyFwdMsg" dir="ltr"><font face="Calibri, sans-serif" style="font-size:11pt" color="#000000"><b>From:</b> Synth-diy <synth-diy-bounces@synth-diy.org> on behalf of Neil Johnson via Synth-diy <synth-diy@synth-diy.org><br>
<b>Sent:</b> 07 November 2022 09:52<br>
<b>To:</b> Lanterman, Aaron D <lanterma@ece.gatech.edu><br>
<b>Cc:</b> synth-diy mailing list <synth-diy@synth-diy.org><br>
<b>Subject:</b> Re: [sdiy] Driving SSI2144 freq control with PWM from a microcontroller</font>
<div> </div>
</div>
<div class="BodyFragment"><font size="2"><span style="font-size:11pt;">
<div class="PlainText">Hi all,<br>
<br>
Genuinely curious question: since you're driving a low-pass filter<br>
anyway, why not dispense with filtering the PWM and, assuming the PWM<br>
clock is way above audio, just drive the frequency control pin<br>
directly? You'll be driving the transistor ladder directly from PWM<br>
so it would behave more as a switched-capacitor filter rather than in<br>
linear mode, but it might work.<br>
For the SSI2144 that would be, say, +/- 90mV pulse waveform.<br>
<br>
Neil<br>
_______________________________________________<br>
Synth-diy mailing list<br>
Synth-diy@synth-diy.org<br>
<a href="http://synth-diy.org/mailman/listinfo/synth-diy">http://synth-diy.org/mailman/listinfo/synth-diy</a><br>
Selling or trading? Use marketplace@synth-diy.org<br>
</div>
</span></font></div>
</body>
</html>