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WindVane.cpp@0:457832d52954, 2012-02-25 (annotated)
- Committer:
- AdamGreen
- Date:
- Sat Feb 25 03:23:51 2012 +0000
- Revision:
- 0:457832d52954
Who changed what in which revision?
User | Revision | Line number | New contents of line |
---|---|---|---|
AdamGreen | 0:457832d52954 | 1 | /* Copyright 2012 Adam Green (http://mbed.org/users/AdamGreen/) |
AdamGreen | 0:457832d52954 | 2 | |
AdamGreen | 0:457832d52954 | 3 | Licensed under the Apache License, Version 2.0 (the "License"); |
AdamGreen | 0:457832d52954 | 4 | you may not use this file except in compliance with the License. |
AdamGreen | 0:457832d52954 | 5 | You may obtain a copy of the License at |
AdamGreen | 0:457832d52954 | 6 | |
AdamGreen | 0:457832d52954 | 7 | http://www.apache.org/licenses/LICENSE-2.0 |
AdamGreen | 0:457832d52954 | 8 | |
AdamGreen | 0:457832d52954 | 9 | Unless required by applicable law or agreed to in writing, software |
AdamGreen | 0:457832d52954 | 10 | distributed under the License is distributed on an "AS IS" BASIS, |
AdamGreen | 0:457832d52954 | 11 | WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. |
AdamGreen | 0:457832d52954 | 12 | See the License for the specific language governing permissions and |
AdamGreen | 0:457832d52954 | 13 | limitations under the License. |
AdamGreen | 0:457832d52954 | 14 | */ |
AdamGreen | 0:457832d52954 | 15 | /* Declaration of class to interface with wind vane sensor Sparkfun Weather Meters: |
AdamGreen | 0:457832d52954 | 16 | http://www.sparkfun.com/products/8942 |
AdamGreen | 0:457832d52954 | 17 | */ |
AdamGreen | 0:457832d52954 | 18 | #include <mbed.h> |
AdamGreen | 0:457832d52954 | 19 | #include "WindVane.h" |
AdamGreen | 0:457832d52954 | 20 | |
AdamGreen | 0:457832d52954 | 21 | |
AdamGreen | 0:457832d52954 | 22 | #define REV_PER_SECOND_TO_KMPH 2.4f |
AdamGreen | 0:457832d52954 | 23 | #define PARALLEL_R(R1, R2) (((R1) * (R2)) / ((R1) + (R2))) |
AdamGreen | 0:457832d52954 | 24 | #define ARRAY_SIZE(X) (sizeof(X)/sizeof(X[0])) |
AdamGreen | 0:457832d52954 | 25 | |
AdamGreen | 0:457832d52954 | 26 | struct SDescription |
AdamGreen | 0:457832d52954 | 27 | { |
AdamGreen | 0:457832d52954 | 28 | const char* DirectionString; |
AdamGreen | 0:457832d52954 | 29 | float DirectionAngle; |
AdamGreen | 0:457832d52954 | 30 | float SensorResistance; |
AdamGreen | 0:457832d52954 | 31 | }; |
AdamGreen | 0:457832d52954 | 32 | |
AdamGreen | 0:457832d52954 | 33 | |
AdamGreen | 0:457832d52954 | 34 | static SDescription g_WindVaneDescriptionTable[16] = { |
AdamGreen | 0:457832d52954 | 35 | { "North", 0.0f, 33.0f * 1000.0f }, |
AdamGreen | 0:457832d52954 | 36 | { "North North East", 22.5f, PARALLEL_R(33.0f * 1000.0f, 8.2f * 1000.0f) }, |
AdamGreen | 0:457832d52954 | 37 | { "North East", 45.0f, 8.2f * 1000.0f }, |
AdamGreen | 0:457832d52954 | 38 | { "East North East", 67.5f, PARALLEL_R(8.2f * 1000.0f, 1000.0f) }, |
AdamGreen | 0:457832d52954 | 39 | { "East", 90.0f, 1000.0f }, |
AdamGreen | 0:457832d52954 | 40 | { "East South East", 112.5f, PARALLEL_R(1000.0f, 2.2f * 1000.0f) }, |
AdamGreen | 0:457832d52954 | 41 | { "South East", 135.0f, 2.2f * 1000.0f }, |
AdamGreen | 0:457832d52954 | 42 | { "South South East", 157.5f, PARALLEL_R(2.2f * 1000.0f, 3.9f * 1000.0f) }, |
AdamGreen | 0:457832d52954 | 43 | { "South", 180.0f, 3.9f * 1000.0f }, |
AdamGreen | 0:457832d52954 | 44 | { "South South West", 202.5f, PARALLEL_R(3.9f * 1000.0f, 16.0f * 1000.0f) }, |
AdamGreen | 0:457832d52954 | 45 | { "South West", 225.0f, 16.0f * 1000.0f }, |
AdamGreen | 0:457832d52954 | 46 | { "West South West", 247.5f, PARALLEL_R(16.0f * 1000.0f, 120.0f * 1000.0f) }, |
AdamGreen | 0:457832d52954 | 47 | { "West", 270.0f, 120.0f * 1000.0f }, |
AdamGreen | 0:457832d52954 | 48 | { "West North West", 292.5f, PARALLEL_R(120.0f * 1000.0f, 64.9f * 1000.0f) }, |
AdamGreen | 0:457832d52954 | 49 | { "North West", 315.0f, 64.9f * 1000.0f }, |
AdamGreen | 0:457832d52954 | 50 | { "North North West", 337.5f, PARALLEL_R(64.9f * 1000.0f, 33.0f * 1000.0f) } |
AdamGreen | 0:457832d52954 | 51 | }; |
AdamGreen | 0:457832d52954 | 52 | |
AdamGreen | 0:457832d52954 | 53 | |
AdamGreen | 0:457832d52954 | 54 | CWindVane::CWindVane(PinName WindVanePin, float WindVaneSeriesResistance) |
AdamGreen | 0:457832d52954 | 55 | : m_WindVaneAnalogIn(WindVanePin) |
AdamGreen | 0:457832d52954 | 56 | { |
AdamGreen | 0:457832d52954 | 57 | for (size_t i = 0 ; i < ARRAY_SIZE(g_WindVaneDescriptionTable) ; i++) |
AdamGreen | 0:457832d52954 | 58 | { |
AdamGreen | 0:457832d52954 | 59 | SDescription* pDescription = &g_WindVaneDescriptionTable[i]; |
AdamGreen | 0:457832d52954 | 60 | |
AdamGreen | 0:457832d52954 | 61 | m_WindVaneVoltageTable[i] = pDescription->SensorResistance / |
AdamGreen | 0:457832d52954 | 62 | (pDescription->SensorResistance + WindVaneSeriesResistance); |
AdamGreen | 0:457832d52954 | 63 | } |
AdamGreen | 0:457832d52954 | 64 | } |
AdamGreen | 0:457832d52954 | 65 | |
AdamGreen | 0:457832d52954 | 66 | const char* CWindVane::GetWindDirectionAsString() |
AdamGreen | 0:457832d52954 | 67 | { |
AdamGreen | 0:457832d52954 | 68 | return g_WindVaneDescriptionTable[DetermineWindDirectionIndex()].DirectionString; |
AdamGreen | 0:457832d52954 | 69 | } |
AdamGreen | 0:457832d52954 | 70 | |
AdamGreen | 0:457832d52954 | 71 | float CWindVane::GetWindDirectionAsAngle() |
AdamGreen | 0:457832d52954 | 72 | { |
AdamGreen | 0:457832d52954 | 73 | return g_WindVaneDescriptionTable[DetermineWindDirectionIndex()].DirectionAngle; |
AdamGreen | 0:457832d52954 | 74 | } |
AdamGreen | 0:457832d52954 | 75 | |
AdamGreen | 0:457832d52954 | 76 | size_t CWindVane::DetermineWindDirectionIndex() |
AdamGreen | 0:457832d52954 | 77 | { |
AdamGreen | 0:457832d52954 | 78 | float WindVaneSensorVoltage = m_WindVaneAnalogIn.read(); |
AdamGreen | 0:457832d52954 | 79 | |
AdamGreen | 0:457832d52954 | 80 | // Default to the first entry being closest. |
AdamGreen | 0:457832d52954 | 81 | size_t ClosestIndex = 0; |
AdamGreen | 0:457832d52954 | 82 | float ClosestDelta = fabs(m_WindVaneVoltageTable[0] - WindVaneSensorVoltage); |
AdamGreen | 0:457832d52954 | 83 | |
AdamGreen | 0:457832d52954 | 84 | // Walk the rest of the entries to see if there is another which is closer. |
AdamGreen | 0:457832d52954 | 85 | for (size_t i = 1 ; i < ARRAY_SIZE(m_WindVaneVoltageTable) ; i++) |
AdamGreen | 0:457832d52954 | 86 | { |
AdamGreen | 0:457832d52954 | 87 | float Delta = fabs(m_WindVaneVoltageTable[i] - WindVaneSensorVoltage); |
AdamGreen | 0:457832d52954 | 88 | if (Delta < ClosestDelta) |
AdamGreen | 0:457832d52954 | 89 | { |
AdamGreen | 0:457832d52954 | 90 | ClosestDelta = Delta; |
AdamGreen | 0:457832d52954 | 91 | ClosestIndex = i; |
AdamGreen | 0:457832d52954 | 92 | } |
AdamGreen | 0:457832d52954 | 93 | } |
AdamGreen | 0:457832d52954 | 94 | |
AdamGreen | 0:457832d52954 | 95 | return ClosestIndex; |
AdamGreen | 0:457832d52954 | 96 | } |