test_code / Mbed 2 deprecated nucleo_test_soft_serial

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Dependencies:   mbed

Fork of nucleo_test_soft_serial by Eric Nativel

soft_uart.cpp@1:2bd6dc642bb9, 2021-03-05 (annotated)

Committer:
eric11fr
Date:
Fri Mar 05 09:35:03 2021 +0000
Revision:
1:2bd6dc642bb9
a tester

Who changed what in which revision?

UserRevisionLine numberNew contents of line
eric11fr 1:2bd6dc642bb9 1 // UART.C
eric11fr 1:2bd6dc642bb9 2 //
eric11fr 1:2bd6dc642bb9 3 // Generic software uart written in C, requiring a timer set to 3 times
eric11fr 1:2bd6dc642bb9 4 // the baud rate, and two software read/write pins for the receive and
eric11fr 1:2bd6dc642bb9 5 // transmit functions.
eric11fr 1:2bd6dc642bb9 6 //
eric11fr 1:2bd6dc642bb9 7 // * Received characters are buffered
eric11fr 1:2bd6dc642bb9 8 // * putchar(), getchar(), kbhit() and flush_input_buffer() are available
eric11fr 1:2bd6dc642bb9 9 // * There is a facility for background processing while waiting for input
eric11fr 1:2bd6dc642bb9 10 //
eric11fr 1:2bd6dc642bb9 11 // Colin Gittins, Software Engineer, Halliburton Energy Services
eric11fr 1:2bd6dc642bb9 12 //
eric11fr 1:2bd6dc642bb9 13 // The baud rate can be configured by changing the BAUD_RATE macro as
eric11fr 1:2bd6dc642bb9 14 // follows:
eric11fr 1:2bd6dc642bb9 15 //
eric11fr 1:2bd6dc642bb9 16 // #define BAUD_RATE 19200.0
eric11fr 1:2bd6dc642bb9 17 //
eric11fr 1:2bd6dc642bb9 18 // The function init_uart() must be called before any comms can take place
eric11fr 1:2bd6dc642bb9 19 //
eric11fr 1:2bd6dc642bb9 20 // Interface routines required:
eric11fr 1:2bd6dc642bb9 21 // 1. get_rx_pin_status()
eric11fr 1:2bd6dc642bb9 22 // Returns 0 or 1 dependent on whether the receive pin is high or low.
eric11fr 1:2bd6dc642bb9 23 // 2. set_tx_pin_high()
eric11fr 1:2bd6dc642bb9 24 // Sets the transmit pin to the high state.
eric11fr 1:2bd6dc642bb9 25 // 3. set_tx_pin_low()
eric11fr 1:2bd6dc642bb9 26 // Sets the transmit pin to the low state.
eric11fr 1:2bd6dc642bb9 27 // 4. idle()
eric11fr 1:2bd6dc642bb9 28 // Background functions to execute while waiting for input.
eric11fr 1:2bd6dc642bb9 29 // 5. timer_set( BAUD_RATE )
eric11fr 1:2bd6dc642bb9 30 // Sets the timer to 3 times the baud rate.
eric11fr 1:2bd6dc642bb9 31 // 6. set_timer_interrupt( timer_isr )
eric11fr 1:2bd6dc642bb9 32 // Enables the timer interrupt.
eric11fr 1:2bd6dc642bb9 33 //
eric11fr 1:2bd6dc642bb9 34 // Functions provided:
eric11fr 1:2bd6dc642bb9 35 // 1. void flush_input_buffer( void )
eric11fr 1:2bd6dc642bb9 36 // Clears the contents of the input buffer.
eric11fr 1:2bd6dc642bb9 37 // 2. char kbhit( void )
eric11fr 1:2bd6dc642bb9 38 // Tests whether an input character has been received.
eric11fr 1:2bd6dc642bb9 39 // 3. char getchar( void )
eric11fr 1:2bd6dc642bb9 40 // Reads a character from the input buffer, waiting if necessary.
eric11fr 1:2bd6dc642bb9 41 // 4. void turn_rx_on( void )
eric11fr 1:2bd6dc642bb9 42 // Turns on the receive function.
eric11fr 1:2bd6dc642bb9 43 // 5. void turn_rx_off( void )
eric11fr 1:2bd6dc642bb9 44 // Turns off the receive function.
eric11fr 1:2bd6dc642bb9 45 // 6. void putchar( char )
eric11fr 1:2bd6dc642bb9 46 // Writes a character to the serial port.
eric11fr 1:2bd6dc642bb9 47 #include "mbed.h"
eric11fr 1:2bd6dc642bb9 48 #include <stdio.h>
eric11fr 1:2bd6dc642bb9 49
eric11fr 1:2bd6dc642bb9 50 #define BAUD_RATE 9600
eric11fr 1:2bd6dc642bb9 51 #define IN_BUF_SIZE 256
eric11fr 1:2bd6dc642bb9 52
eric11fr 1:2bd6dc642bb9 53 #define TRUE 1
eric11fr 1:2bd6dc642bb9 54 #define FALSE 0
eric11fr 1:2bd6dc642bb9 55
eric11fr 1:2bd6dc642bb9 56 static unsigned char inbuf[IN_BUF_SIZE];
eric11fr 1:2bd6dc642bb9 57 static unsigned char qin = 0;
eric11fr 1:2bd6dc642bb9 58 static unsigned char qout = 0;
eric11fr 1:2bd6dc642bb9 59
eric11fr 1:2bd6dc642bb9 60 static char flag_rx_waiting_for_stop_bit;
eric11fr 1:2bd6dc642bb9 61 static char flag_rx_off;
eric11fr 1:2bd6dc642bb9 62 static char rx_mask;
eric11fr 1:2bd6dc642bb9 63 static char flag_rx_ready;
eric11fr 1:2bd6dc642bb9 64 static char flag_tx_ready;
eric11fr 1:2bd6dc642bb9 65 static char timer_rx_ctr;
eric11fr 1:2bd6dc642bb9 66 static char timer_tx_ctr;
eric11fr 1:2bd6dc642bb9 67 static char bits_left_in_rx;
eric11fr 1:2bd6dc642bb9 68 static char bits_left_in_tx;
eric11fr 1:2bd6dc642bb9 69 static char rx_num_of_bits;
eric11fr 1:2bd6dc642bb9 70 static char tx_num_of_bits;
eric11fr 1:2bd6dc642bb9 71 static int internal_rx_buffer;
eric11fr 1:2bd6dc642bb9 72 static int internal_tx_buffer;
eric11fr 1:2bd6dc642bb9 73 static int user_tx_buffer;
eric11fr 1:2bd6dc642bb9 74
eric11fr 1:2bd6dc642bb9 75 DigitalOut TX(PA_4);
eric11fr 1:2bd6dc642bb9 76 DigitalIn RX(PA_3);
eric11fr 1:2bd6dc642bb9 77 Ticker ticker;
eric11fr 1:2bd6dc642bb9 78
eric11fr 1:2bd6dc642bb9 79
eric11fr 1:2bd6dc642bb9 80
eric11fr 1:2bd6dc642bb9 81 //Background functions to execute while waiting for input.
eric11fr 1:2bd6dc642bb9 82 void idle(){
eric11fr 1:2bd6dc642bb9 83 wait_us(0.2);
eric11fr 1:2bd6dc642bb9 84 }
eric11fr 1:2bd6dc642bb9 85
eric11fr 1:2bd6dc642bb9 86 //Sets the transmit pin to the high state.
eric11fr 1:2bd6dc642bb9 87 void set_tx_pin_high() {
eric11fr 1:2bd6dc642bb9 88 TX = 1;
eric11fr 1:2bd6dc642bb9 89 }
eric11fr 1:2bd6dc642bb9 90
eric11fr 1:2bd6dc642bb9 91 //Sets the transmit pin to the low state.
eric11fr 1:2bd6dc642bb9 92 void set_tx_pin_low() {
eric11fr 1:2bd6dc642bb9 93 TX = 0;
eric11fr 1:2bd6dc642bb9 94 }
eric11fr 1:2bd6dc642bb9 95
eric11fr 1:2bd6dc642bb9 96 //Returns 0 or 1 dependent on whether the receive pin is high or low
eric11fr 1:2bd6dc642bb9 97 int get_rx_pin_status() {
eric11fr 1:2bd6dc642bb9 98 return RX.read();
eric11fr 1:2bd6dc642bb9 99 }
eric11fr 1:2bd6dc642bb9 100
eric11fr 1:2bd6dc642bb9 101 void timer_isr(void)
eric11fr 1:2bd6dc642bb9 102 {
eric11fr 1:2bd6dc642bb9 103 char mask, start_bit, flag_in;
eric11fr 1:2bd6dc642bb9 104
eric11fr 1:2bd6dc642bb9 105
eric11fr 1:2bd6dc642bb9 106 // Transmitter Section
eric11fr 1:2bd6dc642bb9 107 if ( flag_tx_ready )
eric11fr 1:2bd6dc642bb9 108 {
eric11fr 1:2bd6dc642bb9 109
eric11fr 1:2bd6dc642bb9 110 if ( --timer_tx_ctr<=0 )
eric11fr 1:2bd6dc642bb9 111 {
eric11fr 1:2bd6dc642bb9 112 mask = internal_tx_buffer&1;
eric11fr 1:2bd6dc642bb9 113 internal_tx_buffer >>= 1;
eric11fr 1:2bd6dc642bb9 114 if ( mask )
eric11fr 1:2bd6dc642bb9 115 {
eric11fr 1:2bd6dc642bb9 116 set_tx_pin_high();
eric11fr 1:2bd6dc642bb9 117 }
eric11fr 1:2bd6dc642bb9 118 else
eric11fr 1:2bd6dc642bb9 119 {
eric11fr 1:2bd6dc642bb9 120 set_tx_pin_low();
eric11fr 1:2bd6dc642bb9 121 }
eric11fr 1:2bd6dc642bb9 122 timer_tx_ctr = 3;
eric11fr 1:2bd6dc642bb9 123 if ( --bits_left_in_tx<=0 )
eric11fr 1:2bd6dc642bb9 124 {
eric11fr 1:2bd6dc642bb9 125 flag_tx_ready = FALSE;
eric11fr 1:2bd6dc642bb9 126 }
eric11fr 1:2bd6dc642bb9 127 }
eric11fr 1:2bd6dc642bb9 128 }
eric11fr 1:2bd6dc642bb9 129 // Receiver Section
eric11fr 1:2bd6dc642bb9 130 if ( flag_rx_off==FALSE )
eric11fr 1:2bd6dc642bb9 131 {
eric11fr 1:2bd6dc642bb9 132 if ( flag_rx_waiting_for_stop_bit )
eric11fr 1:2bd6dc642bb9 133 {
eric11fr 1:2bd6dc642bb9 134 if ( --timer_rx_ctr<=0 )
eric11fr 1:2bd6dc642bb9 135 {
eric11fr 1:2bd6dc642bb9 136 flag_rx_waiting_for_stop_bit = FALSE;
eric11fr 1:2bd6dc642bb9 137 flag_rx_ready = FALSE;
eric11fr 1:2bd6dc642bb9 138 internal_rx_buffer &= 0xFF;
eric11fr 1:2bd6dc642bb9 139 if ( internal_rx_buffer!=0xC2 )
eric11fr 1:2bd6dc642bb9 140 {
eric11fr 1:2bd6dc642bb9 141 inbuf[qin] = internal_rx_buffer;
eric11fr 1:2bd6dc642bb9 142 if ( ++qin>=IN_BUF_SIZE )
eric11fr 1:2bd6dc642bb9 143 {
eric11fr 1:2bd6dc642bb9 144 qin = 0;
eric11fr 1:2bd6dc642bb9 145 }
eric11fr 1:2bd6dc642bb9 146 }
eric11fr 1:2bd6dc642bb9 147 }
eric11fr 1:2bd6dc642bb9 148 }
eric11fr 1:2bd6dc642bb9 149 else // rx_test_busy
eric11fr 1:2bd6dc642bb9 150 {
eric11fr 1:2bd6dc642bb9 151 if ( flag_rx_ready==FALSE )
eric11fr 1:2bd6dc642bb9 152 {
eric11fr 1:2bd6dc642bb9 153 start_bit = get_rx_pin_status();
eric11fr 1:2bd6dc642bb9 154 // Test for Start Bit
eric11fr 1:2bd6dc642bb9 155 if ( start_bit==0 )
eric11fr 1:2bd6dc642bb9 156 {
eric11fr 1:2bd6dc642bb9 157 flag_rx_ready = TRUE;
eric11fr 1:2bd6dc642bb9 158 internal_rx_buffer = 0;
eric11fr 1:2bd6dc642bb9 159 timer_rx_ctr = 4;
eric11fr 1:2bd6dc642bb9 160 bits_left_in_rx = rx_num_of_bits;
eric11fr 1:2bd6dc642bb9 161 rx_mask = 1;
eric11fr 1:2bd6dc642bb9 162 }
eric11fr 1:2bd6dc642bb9 163 }
eric11fr 1:2bd6dc642bb9 164 else // rx_busy
eric11fr 1:2bd6dc642bb9 165 {
eric11fr 1:2bd6dc642bb9 166 if ( --timer_rx_ctr<=0 )
eric11fr 1:2bd6dc642bb9 167 { // rcv
eric11fr 1:2bd6dc642bb9 168 timer_rx_ctr = 3;
eric11fr 1:2bd6dc642bb9 169 flag_in = get_rx_pin_status();
eric11fr 1:2bd6dc642bb9 170 if ( flag_in )
eric11fr 1:2bd6dc642bb9 171 {
eric11fr 1:2bd6dc642bb9 172 internal_rx_buffer |= rx_mask;
eric11fr 1:2bd6dc642bb9 173 }
eric11fr 1:2bd6dc642bb9 174 rx_mask <<= 1;
eric11fr 1:2bd6dc642bb9 175 if ( --bits_left_in_rx<=0 )
eric11fr 1:2bd6dc642bb9 176 {
eric11fr 1:2bd6dc642bb9 177 flag_rx_waiting_for_stop_bit = TRUE;
eric11fr 1:2bd6dc642bb9 178 }
eric11fr 1:2bd6dc642bb9 179 }
eric11fr 1:2bd6dc642bb9 180 }
eric11fr 1:2bd6dc642bb9 181 }
eric11fr 1:2bd6dc642bb9 182 }
eric11fr 1:2bd6dc642bb9 183 }
eric11fr 1:2bd6dc642bb9 184
eric11fr 1:2bd6dc642bb9 185 void init_uart( void )
eric11fr 1:2bd6dc642bb9 186 {
eric11fr 1:2bd6dc642bb9 187 flag_tx_ready = FALSE;
eric11fr 1:2bd6dc642bb9 188 flag_rx_ready = FALSE;
eric11fr 1:2bd6dc642bb9 189 flag_rx_waiting_for_stop_bit = FALSE;
eric11fr 1:2bd6dc642bb9 190 flag_rx_off = FALSE;
eric11fr 1:2bd6dc642bb9 191 rx_num_of_bits = 8;//10
eric11fr 1:2bd6dc642bb9 192 tx_num_of_bits = 10;//10
eric11fr 1:2bd6dc642bb9 193
eric11fr 1:2bd6dc642bb9 194 set_tx_pin_low();
eric11fr 1:2bd6dc642bb9 195 ticker.attach_us(&timer_isr, 1000000.0 / (BAUD_RATE * 3.0));
eric11fr 1:2bd6dc642bb9 196
eric11fr 1:2bd6dc642bb9 197 }
eric11fr 1:2bd6dc642bb9 198
eric11fr 1:2bd6dc642bb9 199 char _getchar( void )
eric11fr 1:2bd6dc642bb9 200 {
eric11fr 1:2bd6dc642bb9 201 char ch;
eric11fr 1:2bd6dc642bb9 202
eric11fr 1:2bd6dc642bb9 203 do
eric11fr 1:2bd6dc642bb9 204 {
eric11fr 1:2bd6dc642bb9 205 while ( qout==qin )
eric11fr 1:2bd6dc642bb9 206 {
eric11fr 1:2bd6dc642bb9 207 idle();
eric11fr 1:2bd6dc642bb9 208 }
eric11fr 1:2bd6dc642bb9 209 ch = inbuf[qout] & 0xFF;
eric11fr 1:2bd6dc642bb9 210 if ( ++qout>=IN_BUF_SIZE )
eric11fr 1:2bd6dc642bb9 211 {
eric11fr 1:2bd6dc642bb9 212 qout = 0;
eric11fr 1:2bd6dc642bb9 213 }
eric11fr 1:2bd6dc642bb9 214 }
eric11fr 1:2bd6dc642bb9 215 while ( ch==0x0A || ch==0xC2 );
eric11fr 1:2bd6dc642bb9 216 return( ch );
eric11fr 1:2bd6dc642bb9 217 }
eric11fr 1:2bd6dc642bb9 218
eric11fr 1:2bd6dc642bb9 219 void _putchar( int ch )
eric11fr 1:2bd6dc642bb9 220 {
eric11fr 1:2bd6dc642bb9 221 while ( flag_tx_ready );
eric11fr 1:2bd6dc642bb9 222 user_tx_buffer = ch;
eric11fr 1:2bd6dc642bb9 223
eric11fr 1:2bd6dc642bb9 224 // invoke_UART_transmit
eric11fr 1:2bd6dc642bb9 225 timer_tx_ctr = 3;
eric11fr 1:2bd6dc642bb9 226 bits_left_in_tx = tx_num_of_bits;
eric11fr 1:2bd6dc642bb9 227 internal_tx_buffer = (user_tx_buffer<<1) | 0x200;;
eric11fr 1:2bd6dc642bb9 228 flag_tx_ready = TRUE;
eric11fr 1:2bd6dc642bb9 229 }
eric11fr 1:2bd6dc642bb9 230
eric11fr 1:2bd6dc642bb9 231 void flush_input_buffer( void )
eric11fr 1:2bd6dc642bb9 232 {
eric11fr 1:2bd6dc642bb9 233 qin = 0;
eric11fr 1:2bd6dc642bb9 234 qout = 0;
eric11fr 1:2bd6dc642bb9 235 }
eric11fr 1:2bd6dc642bb9 236
eric11fr 1:2bd6dc642bb9 237 char kbhit( void )
eric11fr 1:2bd6dc642bb9 238 {
eric11fr 1:2bd6dc642bb9 239 return( qin!=qout );
eric11fr 1:2bd6dc642bb9 240 }
eric11fr 1:2bd6dc642bb9 241
eric11fr 1:2bd6dc642bb9 242 void turn_rx_on( void )
eric11fr 1:2bd6dc642bb9 243 {
eric11fr 1:2bd6dc642bb9 244 flag_rx_off = FALSE;
eric11fr 1:2bd6dc642bb9 245 }
eric11fr 1:2bd6dc642bb9 246
eric11fr 1:2bd6dc642bb9 247 void turn_rx_off( void )
eric11fr 1:2bd6dc642bb9 248 {
eric11fr 1:2bd6dc642bb9 249 flag_rx_off = TRUE;
eric11fr 1:2bd6dc642bb9 250 }
eric11fr 1:2bd6dc642bb9 251
eric11fr 1:2bd6dc642bb9 252 void printStr(char* str){
eric11fr 1:2bd6dc642bb9 253 int i = 0;
eric11fr 1:2bd6dc642bb9 254 int len = strlen(str);
eric11fr 1:2bd6dc642bb9 255 // pc.printf(":%d",len);
eric11fr 1:2bd6dc642bb9 256 for(i = 0; i<len; i++){
eric11fr 1:2bd6dc642bb9 257 wait(0.01);
eric11fr 1:2bd6dc642bb9 258 _putchar(str[i]);
eric11fr 1:2bd6dc642bb9 259 }
eric11fr 1:2bd6dc642bb9 260 }
eric11fr 1:2bd6dc642bb9 261