// // hello.load.45.c // // step response loading 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 // Several Macros #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 101 // bit delay for 9600 with overhead PLAY WITH THIS IF COMPUTER HAS TROUBLE READING SENSOR BOARD INPUT. SYMPTOM: UNSTABLE SCREEN INPUT #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(10) // 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 // The statements below test each bit of the txchar supplied and serially set those 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(); } int main(void) { // // main // static unsigned char up_lo,up_hi,down_lo,down_hi; // // set clock divider to /1 // // The CLKPCE bit must be written to logic one to enable change of the CLKPS bits (done next). // The CLKPCE bit is only updated when the other bits in CLKPR are simultaniosly written to zero. CLKPR = (1 << CLKPCE); // CLKPS3-0 set to 0000, which means that the clock is divided by 1 to derive the internal clock CLKPR = (0 << CLKPS3) | (0 << CLKPS2) | (0 << CLKPS1) | (0 << CLKPS0); // // initialize output pins // // Activate Pull up resistor on PB2 (PIN 2 of PORTB) set(serial_port, serial_pin_out); // Define PIN2 on PORTB as output pin output(serial_direction, serial_pin_out); // Clear PB3, where the shield pins of the sensor are connected clear(charge_port, charge_pin); // Define PB3 as an output 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 as input ADCSRA = (1 << ADEN) // enable ADC | (1 << ADPS2) | (1 << ADPS1) | (1 << ADPS0); // prescaler /128. System clock frequency/input to ADC. // // main loop // while (1) { // // send framing // put_char(&serial_port, serial_pin_out, 1); char_delay(); put_char(&serial_port, serial_pin_out, 2); char_delay(); put_char(&serial_port, serial_pin_out, 3); char_delay(); put_char(&serial_port, serial_pin_out, 4); // // The follwing sequence takes three readings of ADC. For each reading, one ADC sample is taken // when PB3 is high and one when PB3 is low. // The ADC readings in the first round is taken after 1ms, in the second after 10 ms, and in the // third after 100 ms // Below is the first round with 1ms delay // // settle, charge, and wait 1 // Set PB3 // settle_delay(); set(charge_port, charge_pin); charge_delay_1(); // // initiate conversion // ADCSRA |= (1 << ADSC); // // wait for completion. ADSC reads 1 while the conversion is in progress. // while (ADCSRA & (1 << ADSC)) ; // // save result // up_lo = ADCL; up_hi = ADCH; // // 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_lo = ADCL; down_hi = ADCH; // // send result // put_char(&serial_port, serial_pin_out, up_lo); char_delay(); put_char(&serial_port, serial_pin_out, up_hi); char_delay(); put_char(&serial_port, serial_pin_out, down_lo); char_delay(); put_char(&serial_port, serial_pin_out, down_hi); 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_lo = ADCL; up_hi = ADCH; // // 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_lo = ADCL; down_hi = ADCH; // // send result // put_char(&serial_port, serial_pin_out, up_lo); char_delay(); put_char(&serial_port, serial_pin_out, up_hi); char_delay(); put_char(&serial_port, serial_pin_out, down_lo); char_delay(); put_char(&serial_port, serial_pin_out, down_hi); 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_lo = ADCL; up_hi = ADCH; // // 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_lo = ADCL; down_hi = ADCH; // // send result // put_char(&serial_port, serial_pin_out, up_lo); char_delay(); put_char(&serial_port, serial_pin_out, up_hi); char_delay(); put_char(&serial_port, serial_pin_out, down_lo); char_delay(); put_char(&serial_port, serial_pin_out, down_hi); char_delay(); } }