
Fan Speed Control with the EMC2102 Device
5.5Experiment 5 - Optimizing RPM Control Response
This experiment is designed to gain familiarity with the parameters that affect the
For all these tests, the Fan Drive Setting register (51h), the TACH Target register (57h) and the TACH Reading registers (58h) are selected to plot. As bits are switched in each of the tests, the register name and address will be provided.
5.5.2Fan Configuration Register (52h)The Fan Configuration Register stores the basic operation parameters of the
The next two parameters, LIMIT2K and EDGES[1:0] (both in register 52h) describe the fan itself. The EDGES[1:0] tell the controller how many tach edges to examine to determine the fan speed. The LIMIT2K parameter tells the RPM controller how to interpret the TACH Target register (57h). The value of this parameter provides an operating range for the fan by specifying the minimum rpm: the 500 rpm setting is for low speed fans and the 2000 rpm setting is typical for notebook and desktop fans (high speed fans). (Please refer to Section 6.1, "DC Fan Basics - Poles, Tach Meter Pulses and Edges" for more details about the TACH edges and ranges.)
For all experiments in this suite, the default values have been used. This keeps the scaling of those values fixed, allowing the ChipMan application to appropriately scale the counts to RPM values.
The UPDATE[2:0] parameter controls the speed at which the RPM controller updates the output drive, as already been discussed in Section 5.4, "Experiment 4 - RPM Drive Mode Rate Controls". This parameter is independent of the TACH Reading updates, which are controlled by the EDGES[1:0] parameter. The plots in Figure 5.19, "Update Time Modifications" show the effect of UPDATE on the
0.1s 0.2s 0.4s 0.8s 1.6s
Invalid TACH signals (Ignored by Controller)
Figure 5.19 Update Time ModificationsSMSC EMC2102 | USER MANUAL |
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