[phosphor-pid-control] scaling issue

[Hank Liou (劉晉翰)]

Hi Patrick,


{
    "sensors" : [
        {
            "name": "fan1",
            "type": "fan",
            "readPath": "/xyz/openbmc_project/sensors/fan_tach/fan1",
            "writePath": "/sys/devices/platform/ahb/ahb:apb/1e786000.pwm-tacho-controller/hwmon/**/pwm1",
            "min": 0,
            "max": 255
        },
        {
            "name": "temp1",
            "type": "temp",
            "readPath": "/xyz/openbmc_project/sensors/temperature/temp1",
            "writePath": "",
            "min": 0,
            "max": 0
        }
    ],
    "zones" : [
        {
            "id": 1,
            "minThermalOutput": 3000.0,
            "failsafePercent": 75.0,
            "pids": [
                {
                    "name": "fan1",
                    "type": "fan",
                    "inputs": ["fan1"],
                    "setpoint": 90.0,
                    "pid": {
                        "samplePeriod": 0.1,
                        "proportionalCoeff": -1.0,
                        "integralCoeff": -0.2,
                        "feedFwdOffsetCoeff": 0.0,
                        "feedFwdGainCoeff": 0.010,
                        "integralLimit_min": 0.0,
                        "integralLimit_max": 0.0,
                        "outLim_min": 30.0,
                        "outLim_max": 100.0,
                        "slewNeg": 0.0,
                        "slewPos": 0.0
                    }
                },
                {
                    "name": "temp1",
                    "type": "temp",
                    "inputs": ["temp1"],
                    "setpoint": 50.0,
                    "pid": {
                        "samplePeriod": 0.1,
                        "proportionalCoeff": -1.0,
                        "integralCoeff": -0.2,
                        "feedFwdOffsetCoeff": 0.0,
                        "feedFwdGainCoeff": 0.010,
                        "integralLimit_min": 0.0,
                        "integralLimit_max": 0.0,
                        "outLim_min": 500.0,
                        "outLim_max": 1500.0,
                        "slewNeg": 0.0,
                        "slewPos": 0.0
                    }
                }
            ]
        }
    ]
}


Sincerely,


Hank Liou

________________________________
From: Patrick Venture <venture at google.com>
Sent: Thursday, March 28, 2019 10:33 PM
To: Hank Liou (劉晉翰)
Cc: openbmc at lists.ozlabs.org
Subject: Re: [phosphor-pid-control] scaling issue

On Thu, Mar 28, 2019 at 3:55 AM Hank Liou (劉晉翰) <Hank.Liou at quantatw.com> wrote:
>
> Hi All,
>
>
> This issue is related to the repository phosphor-pid-control.
>
>
> It is in commit dbuspassive: allow scaling that one added scaling mechanism. However when it comes to pid.cpp, it may encounter scaling mismatch. That is to say, (in fan control stage) the pid takes the scaled values as inputs, but it utilizes unscaled setpoints resulting wrong error terms. Or just change the setpoint value?

Can you share your configuration?  That might simplify the conversation.

>
>
> Thanks,
>
>
> Hank Liou
>
> Quanta Computer Inc.
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