PPMout.h

00001 /**
00002  * @file    PPMout.h
00003  * @brief   PPMout - PPM signal generator for K64F
00004  * @author  Patrick Thomas
00005  * @version 1.0
00006  * @see
00007  *
00008  * Copyright (c) 2016
00009  *
00010  * Licensed under the Apache License, Version 2.0 (the "License");
00011  * you may not use this file except in compliance with the License.
00012  * You may obtain a copy of the License at
00013  *
00014  *     http://www.apache.org/licenses/LICENSE-2.0
00015  *
00016  * Unless required by applicable law or agreed to in writing, software
00017  * distributed under the License is distributed on an "AS IS" BASIS,
00018  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
00019  * See the License for the specific language governing permissions and
00020  * limitations under the License.
00021  */
00022 
00023 #ifndef PPMOUT_H
00024 #define PPMOUT_H
00025 
00026 #include "mbed.h"
00027 
00028 #define PIN(n,min,max) ((n) > (max) ? max : ((n) < (min) ? (min) : (n)))
00029 
00030 // System clock
00031 #define BUS_CLOCK 60000000
00032 #define CLOCK_DIVIDER 12
00033 #define CMT_PPS_VAL (CLOCK_DIVIDER - 1)
00034 
00035 // Step array
00036 #define CHANNELS 8
00037 #define ARRAY_SIZE (CHANNELS + 1)
00038 
00039 // Time parameters
00040 #define STEPS_PER_MS (((BUS_CLOCK/CLOCK_DIVIDER)/8)/1000)
00041 #define GAP_LENGTH_MS 0.3
00042 #define FRAME_LENGTH_MS 22.5
00043 
00044 // PPM parameters
00045 #define PPM_RANGE_MS 1
00046 #define PPM_ZERO_MS 0.7
00047 
00048 // Derived step parameters
00049 #define RANGE_STEPS (PPM_RANGE_MS*STEPS_PER_MS)
00050 #define ZERO_STEPS (PPM_ZERO_MS*STEPS_PER_MS)
00051 #define GAP_STEPS (int) (GAP_LENGTH_MS*STEPS_PER_MS)
00052 #define TOTAL_GAP_STEPS (GAP_STEPS*ARRAY_SIZE)
00053 #define FRAME_STEPS (FRAME_LENGTH_MS*STEPS_PER_MS)
00054 #define MAX_NON_GAP_STEPS (FRAME_STEPS - TOTAL_GAP_STEPS)
00055 
00056 /** A library for producing PPM output on the K64F (pin PTD7) using the CMT (Carrier/Modulator Transmitter) module
00057  *
00058  * Example:
00059  * @code
00060  *  #include "mbed.h"
00061  *  #include "PPMout.h"
00062  *
00063  *  PPMout myPPM;
00064  *  Serial pc(USBTX, USBRX);
00065  *
00066  *  int main()
00067  *  {
00068  *      while(1) {
00069  *
00070  *          char buffer[128];
00071  *          float f;
00072  *       
00073  *          pc.gets(buffer, 5);
00074  *          f = (float) atof(buffer);
00075  *      
00076  *          myPPM.update_channel(0, f);
00077  *      }
00078  *  }
00079  * @endcode
00080  */
00081 
00082 class PPMout {
00083     
00084 private:
00085 
00086     static int count_array[ARRAY_SIZE];
00087     static int counter;
00088 
00089     static void CMT_IRQHandler();
00090     void init();
00091     void set_sync_length();
00092     
00093 public:
00094     
00095     /** Create PPMout instance
00096      */
00097     PPMout();
00098     
00099     /** Update a PPM channel value
00100      *  @param channel The channel to update (0-7)
00101      *  @param value The new value for the channel (0-1)
00102      */
00103     void update_channel(int channel, float value);
00104 };
00105 
00106 #endif