RC Car Electronic Speed Controller...control

[AaronInSpace 4]

Has anyone ever controlled a hobby rc car's Electronic Speed Controller before? It seems like its simple PWM same as the car's servo but mine doesn't behave. Sometimes it runs sometimes it doesn't. It may be that I am using a programmable high-end ESC that doesn't like something about my signal. I'm using the Fusion Novak ESC by the way.

[xmob 26]

Have you tried connecting your output to a servo?

 

If the servo moves predictably, at least you have some confirmation that your code is on the right track.

[HylianSavior 37]

Here's the basic method of using an ESC (make sure you're sending servo signals and not just any old PWM signal!):

-Connect ESC to live power (you may or may not hear beeping)

-After a bit, send a neutral servo signal - i.e. it would keep a servo dead center at 90 degrees

-Sending signals above neutral should move it forward, while sending signals below neutral should move it backwards.

 

At least that's how it works from what I remember. There's always a signal you need to send first to "arm" it. Try a program that does a sweep of a bunch of different PWM values.

[AaronInSpace 4]

Hey Hylian, you may have nailed it. I'm gonna test that now. Yes my code does work as expected as I use it on a servo just fine. I just have problems reliably controlling the ESC. Sometimes it responds (thought not always in the correct direction or speed) but not always. Thanks

[bluehash 1,581]

Make sure you calibrate your controller first.STEP6:

http://www.teamnovak.com/download/instr ... fusion.pdf

 

Before beginning this step, the speed control should be

connected to the receiver and to a charged 6 or 7 cell

battery pack, and the transmitter should be adjusted.

Adjustment of your Fusion speed control is required for

proper operation. When the status LED is red, the speed

control is in the neutral position (no throttle or brake).

When the status LED is green, the speed control is either at

the full throttle or full brake position.

1. CONNECT THE BATTERY

Plug the speed control into a fully charged 6 or 7 cell

nickel-cadmium battery pack.

2. TURN ON TRANSMITTER THEN THE SPEED CONTROL

3. PRESS AND HOLD ESC

[AaronInSpace 4]

Thanks Blue. I have that manual and have previously done that procedure half a dozen times but it doesn't seem to work. I apologize for not having mentioned that earlier. I was mostly just checking to see if that is how ESCs are supposed to work in general.

 

Here's my code to do that procedure if your curious:

#include 
#include "common.h"
#include "main.h"
#include "utility.h"

int up = 0;
int command_0ccr1;

void init_clocks_and_io(void)
{
// Stop watchdog
WDTCTL = WDTPW + WDTHOLD;

// Make P1.0 (red led)and P1.6 (green led) an output. SLAU144E p.8-3
P1DIR |= BIT0 + BIT6;

// Set clock to 1 MHz
DCOCTL= 0;
BCSCTL1= CALBC1_1MHZ;
DCOCTL= CALDCO_1MHZ;

// SMCLK = 1 MHz / 8 = 125 KHz (SLAU144E p.5-15)
BCSCTL2 |= DIVS_3;

// P1.2 = TA0.1 (timer A's output). SLAS694C p.41
P1SEL |= BIT2;              

// PWM period = 125 KHz / 2500 = 50 Hz = 20ms periods
TA0CCR0 = 2500;

// Neutral 1.5 ms (2500/20 = counts per ms) * 1.5ms
TA0CCR1 = 188;

// Source Timer A from SMCLK (TASSEL_2), up mode (MC_1).
// Up mode counts up to TACCR0. SLAU144E p.12-20
TA0CTL = TASSEL_2 | MC_1;

// OUTMOD_7 = Reset/set output when the timer counts to TACCR1/TACCR0
// CCIE = Interrupt when timer counts to TACCR1
TA0CCTL1 = OUTMOD_7 | CCIE;



__enable_interrupt();	
}

void forward_fast(void)
{
command_0ccr1 = 250;
}

void neutral(void)
{
command_0ccr1 = 188;
}

void brake(void)
{
command_0ccr1 = 162;
}

void main(void)
{
// Set up clocks and Timer A
init_clocks_and_io();

while (1)
{
	neutral();
	P1OUT |= BIT0;
	P1OUT &= ~BIT6;
	m_delay(20000);
	forward_fast();
	P1OUT |= BIT6;
	P1OUT &= ~BIT0;
	m_delay(20000);
	brake();
	P1OUT |= BIT0 + BIT6;
	m_delay(20000);		
}
}

// This will be called when timer counts to TACCR1.
#pragma vector=TIMER0_A1_VECTOR 
__interrupt void Timer0_A1 (void)
{
int curr_0ccr1 = TA0CCR1;

// Clear interrupt flag
TA0CCTL1 &= ~CCIFG;

if (curr_0ccr1 != command_0ccr1)
{
	// Wait to set the new TACCR1 until TAR has gone past it, so that we
 		// don't get interrupted again in this period.
 		while (TA0R <= curr_0ccr1);
	TA0CCR1 = command_0ccr1;
} 
}