-------- In message <017ac7d5-751b-4084-a3b3-e5132509c...@n1k.org>, Bob kb8tq writes:
>You may well use a custom set of control parameters for the warmup phase. The easiest way to avoid overshoot is to use a properly damped PI(D), which is _exactly_ the same thing you want once you are out of the warmup phase, so why bother with two different code paths ? But related to this is the question of output/heater resolution[1]. While it is tempting to use a PWM output, it is a recipe for noise injection, and I would not even try it. Delta-Sigma strategies for spreading the noise-spectrum are interesting, but will not save you if the required heater power ends up being a small rational fraction (1/2, 1/3, 1/4 ...) of the full scale. So a proper DAC is called for. I wonder if a "4-20mA" DAC like the AD5421 is a usable programmable heater ? [1] It is relevant to point out that, as *always* the 'I' term should not be enabled until the P(ID) *output* is no longer clamped. -- Poul-Henning Kamp | UNIX since Zilog Zeus 3.20 p...@freebsd.org | TCP/IP since RFC 956 FreeBSD committer | BSD since 4.3-tahoe Never attribute to malice what can adequately be explained by incompetence. _______________________________________________ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
