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switched to fast PWM, added workaround for UART transmission errors

This commit is contained in:
Christian Kroll 2014-06-15 04:27:26 +02:00
parent 1752f5a0a1
commit 39796a93be
2 changed files with 107 additions and 124 deletions
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107
schaltungen/displayboard_servo/software/src/main.c
View File

@ -14,13 +14,17 @@
#define BUFSIZE 10
/* ugly workaround for massive out of sequence power values,
* USART code seems to forget characters from time to time */
#define MAX_ALLOWED_DEVIATION 50
#define MAX_FAILS 3
#define DEBUG2
volatile uint16_t syscounter = 0;
volatile uint16_t power;
uint8_t data_count = 0;
char data_in[BUFSIZE];
volatile uint16_t current_pulse_width = 250;
void reset_input_buffer(void) {
data_count = 0;
@ -28,11 +32,14 @@ void reset_input_buffer(void) {
}
static void timer_init(void) {
// CTC Mode for Timer 1 (16Bit) with prescale of 64
TCCR1B |= _BV(WGM12) | _BV(CS11) | _BV(CS10);
OCR1A = 2250; // set Servo to max. position
TIMSK |= _BV(OCIE1A); // enable timer interrupt
TCCR1A |= _BV(COM1A0); // toggle OCR1A on overflow
// set Timer 1 to fast PWM mode, with prescale of 64, clear OC1A as soon as
// TCNT1 reaches OCR1A, set OC1A as soon as it reaches ICR1
// NOTE: one tick is equivalent to 8 usecs
TCCR1A = _BV(COM1A1) | _BV(WGM11);
TCCR1B = _BV(WGM13) | _BV(WGM12) | _BV(CS11) | _BV(CS10);
ICR1 = 2500; // period of 20 msecs
OCR1A = 250; // inital pulse width of 2 msecs (10% duty cycle)
TIMSK |= _BV(TOIE1); // enable overflow interrupt
// CTC Mode for Timer 0 (8Bit) with prescale of 1024
TCCR0B |= _BV(CS02) | _BV(CS00); // prescaler
@ -47,6 +54,9 @@ static void ports_init(void) {
}
static void work_uart() {
static uint16_t power;
static uint8_t fail_counter = 0;
uint16_t new_power = 0, diff = 0;
uint16_t c = uart_getc();
if ( !(c & UART_NO_DATA) ) {
@ -70,19 +80,28 @@ static void work_uart() {
#endif
if (cur == 13 || cur == '\n') {
new_power = atoi(data_in);
new_power = new_power <= POWER_MAX ? new_power : POWER_MAX;
diff = new_power > power ? new_power - power : power - new_power;
power = atol(data_in);
if(power > POWER_MAX) power = POWER_MAX;
#ifdef DEBUG
uart_puts_P("power = ");
if(diff < MAX_ALLOWED_DEVIATION || fail_counter > MAX_FAILS) {
#ifdef UART_DEBUG
uart_puts_P("Transmitted power = ");
uart_print_uint16(power);
uart_puts_P("\r\n");
#endif
if(power > 0) {
power = new_power;
fail_counter = 0;
set_servo(power);
}
else {
#ifdef UART_DEBUG
uart_puts_P("Oooooooops!!! Transmitted power = ");
uart_print_uint16(new_power);
uart_puts_P("\r\n");
#endif
fail_counter++;
}
reset_input_buffer();
}
}
@ -94,15 +113,10 @@ static void work_uart() {
* \param display The power value from 0 to 400 (including bounds)
*/
void set_servo(uint16_t display) {
int diff;
if( display > POWER_MAX ) display = POWER_MAX;
display = POWER_MAX-display; // invert the value / servo
display = display * 10; // *10 otherwise we need float
display = display / ((POWER_MAX * 10) / SERVO_STEPS);
display = display + SERVO_STEPS;
// invert value and ensure that we don't exceed the limit
display = POWER_MAX - (display < POWER_MAX ? display : POWER_MAX);
// *10 otherwise we need float
display = (display * 10u) / ((POWER_MAX * 10u) / SERVO_STEPS) + SERVO_STEPS;
#ifdef DEBUG
uart_puts_P("display = ");
@ -110,37 +124,11 @@ void set_servo(uint16_t display) {
uart_puts_P("\r\n");
#endif
if( display < 125 ) display = 125; // just make sure, the timer
if( display > 250 ) display = 250; // is never out ouf 20ms grid
// check if timer is currently in the small pulse, then sleep here 2ms
// and do again
if(OCR1A <= 2250) {
_delay_ms(10);
cli();
current_pulse_width = display;
sei();
}
//cli(); // read and write atomic
TIMSK &= ~(_BV(OCIE1A));
diff = OCR1A - (2500-display);
if(diff <=20 && diff >= -20) {
OCR1A = 2500-display;
}
else {
if(diff <=20) {
OCR1A = OCR1A+5;
}
else if ( diff >= -20 ) {
OCR1A = OCR1A-5;
}
}
//sei();
TIMSK |= _BV(OCIE1A);
}
/**
* \brief the method moves the servo one complete cycle
*/
@ -153,17 +141,16 @@ static void demo_display(void) {
wait(100);
}
int main(void) {
sei();
ports_init();
timer_init();
uart_init(UART_BAUD_SELECT(38400,F_CPU));
reset_input_buffer();
// demo_display();
while(1) {
work_uart();
@ -183,14 +170,8 @@ int main(void) {
return(0);
}
/**
* \brief this is our timer for PWM generation and system clock
* the system clock varies a bit, but this does not matter
*/
ISR(TIMER1_COMPA_vect) {
OCR1A = 2500-OCR1A; // Das Servosignal wird aus der Differenz von
// Periodenlänge (2500*0,008ms=20ms) und letztem
// Vergleichswert (OCR1A) gebildet
ISR(TIMER1_OVF_vect) {
OCR1A = current_pulse_width;
}
ISR(TIMER0_COMPA_vect) {

6
schaltungen/displayboard_servo/tester.py
View File

@ -13,7 +13,7 @@ while 1:
tdata = ser.read()
if tdata == 'a':
print power
print 'Local power = ' + str(power)
ser.write(str(power) + '\x0d')
#ser.write('100\n')
ser.flush()
@ -30,7 +30,9 @@ while 1:
if power < 0:
power = 0
incdec = 0
#else:
else:
sys.stdout.write(tdata)
sys.stdout.write(ser.readline())
#data_left = ser.inWaiting()
#tdata += ser.read(data_left)
#print tdata