Kevin Anderson / DataCommClassVersion

Serial communication protocol generic implementation

Dependents:   ClassFRDM ClassLPC

DataComm.cpp@2:ba93026839a9, 2015-03-19 (annotated)

Committer:
askksa12543
Date:
Thu Mar 19 12:02:52 2015 +0000
Revision:
2:ba93026839a9
Parent:
1:9cfb17f74dcd 
initial receive test

Who changed what in which revision?

UserRevisionLine numberNew contents of line
askksa12543 0:60c4436f7667 1 #include "DataComm.h"
askksa12543 0:60c4436f7667 2
askksa12543 1:9cfb17f74dcd 3 //set pin for clock output, initialize it to zero
askksa12543 0:60c4436f7667 4 void DataComm::setClockOut(PinName pin)
askksa12543 0:60c4436f7667 5 {
askksa12543 0:60c4436f7667 6 gpio_init_out_ex(&clock_out, pin, 0);
askksa12543 0:60c4436f7667 7 }
askksa12543 0:60c4436f7667 8
askksa12543 1:9cfb17f74dcd 9 //set pin for clock input
askksa12543 0:60c4436f7667 10 void DataComm::setClockIn(PinName pin)
askksa12543 0:60c4436f7667 11 {
askksa12543 0:60c4436f7667 12 gpio_init_in(&clock_in, pin);
askksa12543 0:60c4436f7667 13 }
askksa12543 0:60c4436f7667 14
askksa12543 1:9cfb17f74dcd 15 //set pin for outgoing serial connection
askksa12543 0:60c4436f7667 16 void DataComm::setSerialOut(PinName pin)
askksa12543 0:60c4436f7667 17 {
askksa12543 0:60c4436f7667 18 gpio_init_out_ex(&serial_out, pin, 0);
askksa12543 0:60c4436f7667 19 }
askksa12543 0:60c4436f7667 20
askksa12543 1:9cfb17f74dcd 21 //set pin for incoming serial connection
askksa12543 0:60c4436f7667 22 void DataComm::setSerialIn(PinName pin)
askksa12543 0:60c4436f7667 23 {
askksa12543 0:60c4436f7667 24 gpio_init_in(&serial_in, pin);
askksa12543 0:60c4436f7667 25 }
askksa12543 0:60c4436f7667 26
askksa12543 1:9cfb17f74dcd 27 //listen for incoming data, check for preamble, return from function if preamble found
askksa12543 0:60c4436f7667 28 void DataComm::listen()
askksa12543 0:60c4436f7667 29 {
askksa12543 1:9cfb17f74dcd 30 //variables
askksa12543 0:60c4436f7667 31 int pre = 0, data_flag = 1;
askksa12543 0:60c4436f7667 32 char temp = 0;
askksa12543 0:60c4436f7667 33
askksa12543 1:9cfb17f74dcd 34 //while preamble not found, load data into the buffer at every clock pulse
askksa12543 0:60c4436f7667 35 while(!pre)
askksa12543 0:60c4436f7667 36 {
askksa12543 0:60c4436f7667 37 //read in data if clock is 1 and data flag is 1
askksa12543 0:60c4436f7667 38 if(gpio_read(&clock_in) && data_flag)
askksa12543 0:60c4436f7667 39 {
askksa12543 0:60c4436f7667 40 //data is left shifted into our temporary variable.
askksa12543 0:60c4436f7667 41 //each new data bit is moved into the least significant bit after the rest of the bits are shifted to the left
askksa12543 0:60c4436f7667 42 //data must be sent from the other microcontroller shifted out from the most significant bit to the least significant bit.
askksa12543 0:60c4436f7667 43 temp = (temp << 1) + gpio_read(&serial_in);
askksa12543 0:60c4436f7667 44 data_flag = 0;
askksa12543 1:9cfb17f74dcd 45 //when preamble is found return from function
askksa12543 0:60c4436f7667 46 if(temp == PREAMBLE)
askksa12543 0:60c4436f7667 47 {
askksa12543 0:60c4436f7667 48 pre = 1;
askksa12543 0:60c4436f7667 49 }
askksa12543 0:60c4436f7667 50 }
askksa12543 0:60c4436f7667 51 //when clock returns to low - reset data flag to accept the next bit.
askksa12543 0:60c4436f7667 52 if(!gpio_read(&clock_in) && !data_flag)
askksa12543 0:60c4436f7667 53 {
askksa12543 0:60c4436f7667 54 data_flag = 1;
askksa12543 0:60c4436f7667 55 }
askksa12543 0:60c4436f7667 56 }
askksa12543 0:60c4436f7667 57 }
askksa12543 0:60c4436f7667 58
askksa12543 1:9cfb17f74dcd 59 //set clock speed for sending data, automatically calculate skew time
askksa12543 0:60c4436f7667 60 void DataComm::setClock(int clock)
askksa12543 0:60c4436f7667 61 {
askksa12543 0:60c4436f7667 62 clock_time = clock;
askksa12543 1:9cfb17f74dcd 63 //skew time 90% of the clock
askksa12543 0:60c4436f7667 64 skew_time = (clock * 9)/10;
askksa12543 0:60c4436f7667 65 }
askksa12543 0:60c4436f7667 66
askksa12543 1:9cfb17f74dcd 67 //initiate a connection with a preamble
askksa12543 0:60c4436f7667 68 void DataComm::initiate_connection()
askksa12543 0:60c4436f7667 69 {
askksa12543 1:9cfb17f74dcd 70 //variables
askksa12543 0:60c4436f7667 71 int j=128, done=0, skew_flag=0;
askksa12543 0:60c4436f7667 72
askksa12543 0:60c4436f7667 73 //output preamble
askksa12543 0:60c4436f7667 74 while(!done)
askksa12543 0:60c4436f7667 75 {
askksa12543 0:60c4436f7667 76 //start timer for clock
askksa12543 0:60c4436f7667 77 t.start();
askksa12543 0:60c4436f7667 78 //wait until the timer has reached the set time.
askksa12543 0:60c4436f7667 79 while(t.read_ms() < clock_time)
askksa12543 0:60c4436f7667 80 {
askksa12543 0:60c4436f7667 81 //extract data just before clock goes high
askksa12543 0:60c4436f7667 82 if(!gpio_read(&clock_out) && skew_flag && t.read_ms() > skew_time)
askksa12543 0:60c4436f7667 83 {
askksa12543 0:60c4436f7667 84 //extract data bit
askksa12543 0:60c4436f7667 85 gpio_write(&serial_out, ((PREAMBLE / j) % 2));
askksa12543 0:60c4436f7667 86 skew_flag = 0;
askksa12543 0:60c4436f7667 87 j /= 2; //decrement j to get to next bit location
askksa12543 0:60c4436f7667 88 }
askksa12543 0:60c4436f7667 89 }
askksa12543 0:60c4436f7667 90 //stop and reset the timer
askksa12543 0:60c4436f7667 91 t.stop();
askksa12543 0:60c4436f7667 92 t.reset();
askksa12543 0:60c4436f7667 93 //switch clock signal
askksa12543 0:60c4436f7667 94 gpio_write(&clock_out, !gpio_read(&clock_out));
askksa12543 0:60c4436f7667 95 //reset skew flag
askksa12543 0:60c4436f7667 96 skew_flag = 1;
askksa12543 1:9cfb17f74dcd 97 //last preamble bit sent - return from function set clock to zero
askksa12543 0:60c4436f7667 98 if(j==0)
askksa12543 0:60c4436f7667 99 {
askksa12543 1:9cfb17f74dcd 100 gpio_write(&clock_out, 0);
askksa12543 0:60c4436f7667 101 done = 1;
askksa12543 0:60c4436f7667 102 }
askksa12543 0:60c4436f7667 103 }
askksa12543 0:60c4436f7667 104 }
askksa12543 0:60c4436f7667 105
askksa12543 1:9cfb17f74dcd 106 //send data from character array of a specific size
askksa12543 1:9cfb17f74dcd 107 void DataComm::send_data(char data[], int size)
askksa12543 0:60c4436f7667 108 {
askksa12543 1:9cfb17f74dcd 109 //variables
askksa12543 0:60c4436f7667 110 int i=0, j=128, done=0, skew_flag=0;
askksa12543 0:60c4436f7667 111
askksa12543 0:60c4436f7667 112 //output data
askksa12543 0:60c4436f7667 113 while(!done)
askksa12543 0:60c4436f7667 114 {
askksa12543 0:60c4436f7667 115 //start timer for clock
askksa12543 0:60c4436f7667 116 t.start();
askksa12543 0:60c4436f7667 117 //wait until the timer has reached the set time.
askksa12543 0:60c4436f7667 118 while(t.read_ms() < clock_time)
askksa12543 0:60c4436f7667 119 {
askksa12543 0:60c4436f7667 120 //extract data just before clock goes high
askksa12543 0:60c4436f7667 121 if(!gpio_read(&clock_out) && skew_flag && t.read_ms() > skew_time)
askksa12543 0:60c4436f7667 122 {
askksa12543 0:60c4436f7667 123 //extract data bit
askksa12543 0:60c4436f7667 124 gpio_write(&serial_out, ((data[i] / j) % 2));
askksa12543 0:60c4436f7667 125 skew_flag = 0;
askksa12543 0:60c4436f7667 126 j /= 2; //decrement j to get to next bit location
askksa12543 0:60c4436f7667 127 }
askksa12543 0:60c4436f7667 128 }
askksa12543 0:60c4436f7667 129 //stop and reset the timer
askksa12543 0:60c4436f7667 130 t.stop();
askksa12543 0:60c4436f7667 131 t.reset();
askksa12543 0:60c4436f7667 132 //switch clock signal
askksa12543 0:60c4436f7667 133 gpio_write(&clock_out, !gpio_read(&clock_out));
askksa12543 0:60c4436f7667 134 //reset skew flag
askksa12543 0:60c4436f7667 135 skew_flag = 1;
askksa12543 1:9cfb17f74dcd 136 //last bit sent - move to next character or return from function
askksa12543 0:60c4436f7667 137 if(j==0)
askksa12543 0:60c4436f7667 138 {
askksa12543 0:60c4436f7667 139 i++;
askksa12543 1:9cfb17f74dcd 140 if(i>size)
askksa12543 1:9cfb17f74dcd 141 {
askksa12543 1:9cfb17f74dcd 142 //return from function, set clock to zero
askksa12543 0:60c4436f7667 143 done = 1;
askksa12543 1:9cfb17f74dcd 144 gpio_write(&clock_out, 0);
askksa12543 1:9cfb17f74dcd 145 }
askksa12543 0:60c4436f7667 146 j=128;
askksa12543 0:60c4436f7667 147 }
askksa12543 0:60c4436f7667 148 }
askksa12543 0:60c4436f7667 149 }
askksa12543 0:60c4436f7667 150
askksa12543 1:9cfb17f74dcd 151 //receive data return pointer to character array that data is stored in
askksa12543 0:60c4436f7667 152 char* DataComm::receive_data()
askksa12543 0:60c4436f7667 153 {
askksa12543 1:9cfb17f74dcd 154 //variables
askksa12543 0:60c4436f7667 155 int i=0, j=0, done = 0, data_flag = 1;
askksa12543 1:9cfb17f74dcd 156 char temp, data[MAX];
askksa12543 0:60c4436f7667 157
askksa12543 1:9cfb17f74dcd 158 //read characters until postamble is found
askksa12543 0:60c4436f7667 159 while(!done)
askksa12543 0:60c4436f7667 160 {
askksa12543 0:60c4436f7667 161 //read in data if clock is 1 and data flag is 1
askksa12543 0:60c4436f7667 162 if(gpio_read(&clock_in) && data_flag)
askksa12543 0:60c4436f7667 163 {
askksa12543 0:60c4436f7667 164 //data is left shifted into our temporary variable.
askksa12543 0:60c4436f7667 165 //each new data bit is moved into the least significant bit after the rest of the bits are shifted to the left
askksa12543 0:60c4436f7667 166 //data must be sent from the other microcontroller shifted out from the most significant bit to the least significant bit.
askksa12543 1:9cfb17f74dcd 167 temp = (temp << 1) + gpio_read(&serial_in);
askksa12543 0:60c4436f7667 168 data_flag = 0;
askksa12543 0:60c4436f7667 169 j++;
askksa12543 0:60c4436f7667 170 }
askksa12543 0:60c4436f7667 171 //when clock returns to low - reset data flag to accept the next bit.
askksa12543 0:60c4436f7667 172 if(!gpio_read(&clock_in) && !data_flag)
askksa12543 0:60c4436f7667 173 {
askksa12543 0:60c4436f7667 174 data_flag = 1;
askksa12543 0:60c4436f7667 175 }
askksa12543 1:9cfb17f74dcd 176 //after filling a new byte check for postamble.
askksa12543 0:60c4436f7667 177 if(j>7)
askksa12543 0:60c4436f7667 178 {
askksa12543 1:9cfb17f74dcd 179 //finished when postamble found, otherwise store the byte
askksa12543 1:9cfb17f74dcd 180 if(temp == POSTAMBLE)
askksa12543 1:9cfb17f74dcd 181 done=1;
askksa12543 1:9cfb17f74dcd 182 else
askksa12543 1:9cfb17f74dcd 183 data[i] = temp;
askksa12543 1:9cfb17f74dcd 184 //increment i, reset j
askksa12543 0:60c4436f7667 185 i++;
askksa12543 0:60c4436f7667 186 j=0;
askksa12543 0:60c4436f7667 187 }
askksa12543 0:60c4436f7667 188 }
askksa12543 1:9cfb17f74dcd 189 return data;
askksa12543 0:60c4436f7667 190 }
askksa12543 1:9cfb17f74dcd 191
askksa12543 1:9cfb17f74dcd 192 //close connection by sending postamble
askksa12543 1:9cfb17f74dcd 193 void DataComm::close_connection()
askksa12543 1:9cfb17f74dcd 194 {
askksa12543 1:9cfb17f74dcd 195 //variables
askksa12543 1:9cfb17f74dcd 196 int j=128, done=0, skew_flag=0;
askksa12543 1:9cfb17f74dcd 197
askksa12543 1:9cfb17f74dcd 198 //output postamble
askksa12543 1:9cfb17f74dcd 199 while(!done)
askksa12543 1:9cfb17f74dcd 200 {
askksa12543 1:9cfb17f74dcd 201 //start timer for clock
askksa12543 1:9cfb17f74dcd 202 t.start();
askksa12543 1:9cfb17f74dcd 203 //wait until the timer has reached the set time.
askksa12543 1:9cfb17f74dcd 204 while(t.read_ms() < clock_time)
askksa12543 1:9cfb17f74dcd 205 {
askksa12543 1:9cfb17f74dcd 206 //extract data just before clock goes high
askksa12543 1:9cfb17f74dcd 207 if(!gpio_read(&clock_out) && skew_flag && t.read_ms() > skew_time)
askksa12543 1:9cfb17f74dcd 208 {
askksa12543 1:9cfb17f74dcd 209 //extract data bit
askksa12543 1:9cfb17f74dcd 210 gpio_write(&serial_out, ((POSTAMBLE / j) % 2));
askksa12543 1:9cfb17f74dcd 211 skew_flag = 0;
askksa12543 1:9cfb17f74dcd 212 j /= 2; //decrement j to get to next bit location
askksa12543 1:9cfb17f74dcd 213 }
askksa12543 1:9cfb17f74dcd 214 }
askksa12543 1:9cfb17f74dcd 215 //stop and reset the timer
askksa12543 1:9cfb17f74dcd 216 t.stop();
askksa12543 1:9cfb17f74dcd 217 t.reset();
askksa12543 1:9cfb17f74dcd 218 //switch clock signal
askksa12543 1:9cfb17f74dcd 219 gpio_write(&clock_out, !gpio_read(&clock_out));
askksa12543 1:9cfb17f74dcd 220 //reset skew flag
askksa12543 1:9cfb17f74dcd 221 skew_flag = 1;
askksa12543 1:9cfb17f74dcd 222 //last postamble bit sent - return from function and set clock to zero
askksa12543 1:9cfb17f74dcd 223 if(j==0)
askksa12543 1:9cfb17f74dcd 224 {
askksa12543 1:9cfb17f74dcd 225 gpio_write(&clock_out, 0);
askksa12543 1:9cfb17f74dcd 226 done = 1;
askksa12543 1:9cfb17f74dcd 227 }
askksa12543 1:9cfb17f74dcd 228 }
askksa12543 1:9cfb17f74dcd 229 }