// // hello.step.45.c // // step response hello-world // 9600 baud FTDI interface // // Neil Gershenfeld // 10/27/10 // // (c) Massachusetts Institute of Technology 2010 // Permission granted for experimental and personal use; // license for commercial sale available from MIT. // #include #include #include #define output(directions,pin) (directions |= pin) // set port direction for output #define set(port,pin) (port |= pin) // set port pin #define clear(port,pin) (port &= (~pin)) // clear port pin #define pin_test(pins,pin) (pins & pin) // test for port pin #define bit_test(byte,bit) (byte & (1 << bit)) // test for bit set #define bit_delay_time 100 // bit delay for 9600 with overhead #define bit_delay() _delay_us(bit_delay_time) // RS232 bit delay #define half_bit_delay() _delay_us(bit_delay_time/2) // RS232 half bit delay #define charge_delay_1() _delay_us(1) // charge delay 1 #define charge_delay_2() _delay_us(10) // charge delay 2 #define charge_delay_3() _delay_us(100) // charge delay 3 #define settle_delay() _delay_us(100) // settle delay #define char_delay() _delay_ms(1) // char delay #define serial_port PORTB #define serial_direction DDRB #define serial_pin_out (1 << PB2) #define charge_port PORTB #define charge_direction DDRB #define charge_pin (1 << PB3) void put_char(volatile unsigned char *port, unsigned char pin, char txchar) { // // send character in txchar on port pin // assumes line driver (inverts bits) // // start bit // clear(*port,pin); bit_delay(); // // unrolled loop to write data bits // if bit_test(txchar,0) set(*port,pin); else clear(*port,pin); bit_delay(); if bit_test(txchar,1) set(*port,pin); else clear(*port,pin); bit_delay(); if bit_test(txchar,2) set(*port,pin); else clear(*port,pin); bit_delay(); if bit_test(txchar,3) set(*port,pin); else clear(*port,pin); bit_delay(); if bit_test(txchar,4) set(*port,pin); else clear(*port,pin); bit_delay(); if bit_test(txchar,5) set(*port,pin); else clear(*port,pin); bit_delay(); if bit_test(txchar,6) set(*port,pin); else clear(*port,pin); bit_delay(); if bit_test(txchar,7) set(*port,pin); else clear(*port,pin); bit_delay(); // // stop bit // set(*port,pin); bit_delay(); // // char delay // bit_delay(); } //a function to write a DEC value to the serial port void put_decimal(uint16_t value){ uint8_t temp[6]; int8_t p = 0; uint8_t i; while(value > 0) { uint8_t cur_digit = value %10; temp[p++] = cur_digit + '0'; value = value/10; } while(p>0){ put_char(&serial_port, serial_pin_out,temp[--p]); char_delay(); } } int main(void) { // // main // static uint16_t up, down; // // set clock divider to /1 // CLKPR = (1 << CLKPCE); CLKPR = (0 << CLKPS3) | (0 << CLKPS2) | (0 << CLKPS1) | (0 << CLKPS0); // // initialize output pins // set(serial_port, serial_pin_out); output(serial_direction, serial_pin_out); clear(charge_port, charge_pin); output(charge_direction, charge_pin); // // init A/D // ADMUX = (0 << REFS2) | (0 << REFS1) | (0 << REFS0) // Vcc ref | (0 << ADLAR) // right adjust | (0 << MUX3) | (0 << MUX2) | (1 << MUX1) | (0 << MUX0); // PB4 ADCSRA = (1 << ADEN) // enable | (1 << ADPS2) | (1 << ADPS1) | (1 << ADPS0); // prescaler /128 // // main loop // while (1) { settle_delay(); set(charge_port, charge_pin); charge_delay_1(); // // initiate conversion // ADCSRA |= (1 << ADSC); // // wait for completion // while (ADCSRA & (1 << ADSC)) ; // // save result up = ADC; // // settle, discharge, and wait 1 // settle_delay(); clear(charge_port, charge_pin); charge_delay_1(); // // initiate conversion // ADCSRA |= (1 << ADSC); // // wait for completion // while (ADCSRA & (1 << ADSC)); // // save result down = ADC; // // send result // //write up value put_decimal(up); //write comma to separate values put_char(&serial_port, serial_pin_out, ','); char_delay(); //write down value put_decimal(down); //write comma to separate values put_char(&serial_port, serial_pin_out, ','); char_delay(); // // settle, charge, and wait 2 // settle_delay(); set(charge_port, charge_pin); charge_delay_2(); // // initiate conversion // ADCSRA |= (1 << ADSC); // // wait for completion // while (ADCSRA & (1 << ADSC)) ; // // save result up = ADC; // // settle, discharge, and wait 2 // settle_delay(); clear(charge_port, charge_pin); charge_delay_2(); // // initiate conversion // ADCSRA |= (1 << ADSC); // // wait for completion // while (ADCSRA & (1 << ADSC)) ; // // save result down = ADC; // // send result // write up value put_decimal(up); //write comma to separate values put_char(&serial_port, serial_pin_out, ','); char_delay(); //write down value put_decimal(down); //write comma to separate values put_char(&serial_port, serial_pin_out, ','); char_delay(); // // settle, charge, and wait 3 // settle_delay(); set(charge_port, charge_pin); charge_delay_3(); // // initiate conversion // ADCSRA |= (1 << ADSC); // // wait for completion // while (ADCSRA & (1 << ADSC)) ; // // save result up = ADC; // // settle, discharge, and wait 3 // settle_delay(); clear(charge_port, charge_pin); charge_delay_3(); // // initiate conversion // ADCSRA |= (1 << ADSC); // // wait for completion // while (ADCSRA & (1 << ADSC)); // // save result down = ADC; // // send result //write the up value put_decimal(up); //write comma to separate the value put_char(&serial_port, serial_pin_out, ','); char_delay(); //write the down value put_decimal(down); //write comma to separate the value put_char(&serial_port, serial_pin_out, ','); char_delay(); //write carriage return -- needed for Firefly to recognize where the end of line is put_char(&serial_port, serial_pin_out, '\r'); char_delay(); //write line feed -- needed for Firefly to recognize where the end of the line is put_char(&serial_port, serial_pin_out, '\n'); char_delay(); _delay_ms(15); } }