M106 linear scaling between L and X

[Mikey]

I created a fan output with

M950 F4 C"PE3" Q100
M106 P4 S0 H-1 L50 X255 C"CPAP"

But when controlling it S[1-50] all set the speed to 50, which makes some sense, as L told it it should start at 50, but is there a way to make it so S0 is off, S1 is converted to 50, and everything from S1-255 is mapped to return 50-255 instead?

My hope is to be able to control the fan normally from S0 to S255, and it then be mapped to something like

M106 S0 > 0
M106 S1 > 50
M106 S2 > 51
M106 S3 > 52
M106 S4 > 52
M106 S5 > 53
M106 S6 > 54
M106 S7 > 55
M106 S8 > 56
M106 S9 > 56
M106 S10 > 57
M106 S11 > 58
M106 S12 > 59
M106 S13 > 60
M106 S14 > 60
M106 S15 > 61
M106 S16 > 62
M106 S17 > 63
M106 S18 > 64
M106 S19 > 65
M106 S20 > 65
M106 S21 > 66
M106 S22 > 67
M106 S23 > 68
M106 S24 > 69
M106 S25 > 69
M106 S26 > 70
M106 S27 > 71
M106 S28 > 72
M106 S29 > 73
M106 S30 > 73
M106 S31 > 74
M106 S32 > 75
M106 S33 > 76
M106 S34 > 77
M106 S35 > 77
M106 S36 > 78
M106 S37 > 79
M106 S38 > 80
M106 S39 > 81
M106 S40 > 81
M106 S41 > 82
M106 S42 > 83
M106 S43 > 84
M106 S44 > 85
M106 S45 > 86
M106 S46 > 86
M106 S47 > 87
M106 S48 > 88
M106 S49 > 89
M106 S50 > 90
M106 S51 > 90
M106 S52 > 91
M106 S53 > 92
M106 S54 > 93
M106 S55 > 94
M106 S56 > 94
M106 S57 > 95
M106 S58 > 96
M106 S59 > 97
M106 S60 > 98
M106 S61 > 98
M106 S62 > 99
M106 S63 > 100
M106 S64 > 101
M106 S65 > 102
M106 S66 > 102
M106 S67 > 103
M106 S68 > 104
M106 S69 > 105
M106 S70 > 106
M106 S71 > 106
M106 S72 > 107
M106 S73 > 108
M106 S74 > 109
M106 S75 > 110
M106 S76 > 111
M106 S77 > 111
M106 S78 > 112
M106 S79 > 113
M106 S80 > 114
M106 S81 > 115
M106 S82 > 115
M106 S83 > 116
M106 S84 > 117
M106 S85 > 118
M106 S86 > 119
M106 S87 > 119
M106 S88 > 120
M106 S89 > 121
M106 S90 > 122
M106 S91 > 123
M106 S92 > 123
M106 S93 > 124
M106 S94 > 125
M106 S95 > 126
M106 S96 > 127
M106 S97 > 127
M106 S98 > 128
M106 S99 > 129
M106 S100 > 130
M106 S101 > 131
M106 S102 > 132
M106 S103 > 132
M106 S104 > 133
M106 S105 > 134
M106 S106 > 135
M106 S107 > 136
M106 S108 > 136
M106 S109 > 137
M106 S110 > 138
M106 S111 > 139
M106 S112 > 140
M106 S113 > 140
M106 S114 > 141
M106 S115 > 142
M106 S116 > 143
M106 S117 > 144
M106 S118 > 144
M106 S119 > 145
M106 S120 > 146
M106 S121 > 147
M106 S122 > 148
M106 S123 > 148
M106 S124 > 149
M106 S125 > 150
M106 S126 > 151
M106 S127 > 152
M106 S128 > 152
M106 S129 > 153
M106 S130 > 154
M106 S131 > 155
M106 S132 > 156
M106 S133 > 157
M106 S134 > 157
M106 S135 > 158
M106 S136 > 159
M106 S137 > 160
M106 S138 > 161
M106 S139 > 161
M106 S140 > 162
M106 S141 > 163
M106 S142 > 164
M106 S143 > 165
M106 S144 > 165
M106 S145 > 166
M106 S146 > 167
M106 S147 > 168
M106 S148 > 169
M106 S149 > 169
M106 S150 > 170
M106 S151 > 171
M106 S152 > 172
M106 S153 > 173
M106 S154 > 173
M106 S155 > 174
M106 S156 > 175
M106 S157 > 176
M106 S158 > 177
M106 S159 > 178
M106 S160 > 178
M106 S161 > 179
M106 S162 > 180
M106 S163 > 181
M106 S164 > 182
M106 S165 > 182
M106 S166 > 183
M106 S167 > 184
M106 S168 > 185
M106 S169 > 186
M106 S170 > 186
M106 S171 > 187
M106 S172 > 188
M106 S173 > 189
M106 S174 > 190
M106 S175 > 190
M106 S176 > 191
M106 S177 > 192
M106 S178 > 193
M106 S179 > 194
M106 S180 > 194
M106 S181 > 195
M106 S182 > 196
M106 S183 > 197
M106 S184 > 198
M106 S185 > 199
M106 S186 > 199
M106 S187 > 200
M106 S188 > 201
M106 S189 > 202
M106 S190 > 203
M106 S191 > 203
M106 S192 > 204
M106 S193 > 205
M106 S194 > 206
M106 S195 > 207
M106 S196 > 207
M106 S197 > 208
M106 S198 > 209
M106 S199 > 210
M106 S200 > 211
M106 S201 > 211
M106 S202 > 212
M106 S203 > 213
M106 S204 > 214
M106 S205 > 215
M106 S206 > 215
M106 S207 > 216
M106 S208 > 217
M106 S209 > 218
M106 S210 > 219
M106 S211 > 219
M106 S212 > 220
M106 S213 > 221
M106 S214 > 222
M106 S215 > 223
M106 S216 > 224
M106 S217 > 224
M106 S218 > 225
M106 S219 > 226
M106 S220 > 227
M106 S221 > 228
M106 S222 > 228
M106 S223 > 229
M106 S224 > 230
M106 S225 > 231
M106 S226 > 232
M106 S227 > 232
M106 S228 > 233
M106 S229 > 234
M106 S230 > 235
M106 S231 > 236
M106 S232 > 236
M106 S233 > 237
M106 S234 > 238
M106 S235 > 239
M106 S236 > 240
M106 S237 > 240
M106 S238 > 241
M106 S239 > 242
M106 S240 > 243
M106 S241 > 244
M106 S242 > 245
M106 S243 > 245
M106 S244 > 246
M106 S245 > 247
M106 S246 > 248
M106 S247 > 249
M106 S248 > 249
M106 S249 > 250
M106 S250 > 251
M106 S251 > 252
M106 S252 > 253
M106 S253 > 253
M106 S254 > 254
M106 S255 > 255

Current behavior verified by sending

M106 P4 S10
M106 P4
Fan 4 (CPAP), speed 3%, min: 19%, max: 100%, blip: 0.10

[deckingman]

@Mikey No, I think you are a bit stuck. My understanding from the documentation is that the fan control is essentially a straight line slope between 0 and 100% speed vs PWM, but you can clip is such that all non-zero values below "L" are set to whatever "L" is and any values above "X" are clipped to whatever "X" is. So in your case 0 should be off, but all values above zero up to 50 will be at 50. From then on it'll ramp up following the original straight line slope from zero to 100% until it reaches "X". What you want to do is add an offset but also change the angle of the slope, which I don't think is currently possible.

EDIT. But I note that you've posted this in the "firmware wish list" section, which is the right place.

[dc42]

@Mikey the behaviour is intentional. If the slicer asks for 20% fan speed but the minimum your fan can do is 30%, then you will get 30% which is the available value closest to the one requested by the slicer. If the slicer requests 30% then you will also get 30%, not 51% which is what your scheme would provide.

RRF does scale the PWM according to the X parameter that you provide, because the purpose of the X parameter is to specify the maximum PWM that you ever want to use.