Very interested in this, can you elaborate on what you have done exactly? It's all quite new to me so what you wrote is not all that clearjoan wrote:I rejigged the Arduino software to use Gordon's WiringPi library, used 6 gpio lines for control, and I can now drive (4) DC motors backwards/forwards with variable speed.
I didn't have any problems with the signal levels. I suppose a 3.3V low is pretty much the same as a 5V low and a 3.3V high is high enough to count as a 5V high.BBsan2k wrote:Sorry for bringing this up again,
but isn't there a problem using 3.3V Raspberry Pi? How did you manage to controll the motor shield?
There are simpler ways to drive motors from the Pi, e.g. http://www.ebay.co.uk/itm/140743762410poing wrote:Very interested in this, can you elaborate on what you have done exactly? It's all quite new to me so what you wrote is not all that clearjoan wrote:I rejigged the Arduino software to use Gordon's WiringPi library, used 6 gpio lines for control, and I can now drive (4) DC motors backwards/forwards with variable speed.
Code: Select all
#include <stdio.h>
#include <errno.h>
#include <string.h>
#include <wiringPi.h>
#include <softPwm.h>
typedef unsigned char uint8_t;
#define _BV(bit) (1 << (bit))
#define MOTORLATCH 0
#define MOTORCLK 1
#define MOTORENABLE 2
#define MOTORDATA 3
#define MOTOR_1_PWM 4
#define MOTOR_2_PWM 5
#define MOTOR1_A 2
#define MOTOR1_B 3
#define MOTOR2_A 1
#define MOTOR2_B 4
#define MOTOR4_A 0
#define MOTOR4_B 6
#define MOTOR3_A 5
#define MOTOR3_B 7
#define FORWARD 1
#define BACKWARD 2
#define BRAKE 3
#define RELEASE 4
#define RANGE 100
#define DC_MOTORS 4
static unsigned char latch_state;
void latch_tx(void)
{
unsigned char i;
digitalWrite(MOTORLATCH, LOW);
digitalWrite(MOTORDATA, LOW);
for (i=0; i<8; i++)
{
digitalWrite(MOTORCLK, LOW);
if (latch_state & _BV(7-i))
{
digitalWrite(MOTORDATA, HIGH);
}
else
{
digitalWrite(MOTORDATA, LOW);
}
digitalWrite(MOTORCLK, HIGH);
}
digitalWrite(MOTORLATCH, HIGH);
}
void enable(void)
{
pinMode(MOTORLATCH, OUTPUT);
pinMode(MOTORENABLE, OUTPUT);
pinMode(MOTORDATA, OUTPUT);
pinMode(MOTORCLK, OUTPUT);
latch_state = 0;
latch_tx();
digitalWrite(MOTORENABLE, LOW);
}
typedef struct motorInf_t
{
uint8_t pwmfreq;
};
motorInt_t motorInf[DC_MOTORS];
void DCMotorInit(uint8_t num, uint8_t freq)
{
motorInf[num].pwmfreq = freq;
enable();
switch (num)
{
case 1:
latch_state &= ~_BV(MOTOR1_A) & ~_BV(MOTOR1_B);
latch_tx();
initPWM(1, freq);
break;
case 2:
latch_state &= ~_BV(MOTOR2_A) & ~_BV(MOTOR2_B);
latch_tx();
initPWM(2, freq);
break;
case 3:
latch_state &= ~_BV(MOTOR3_A) & ~_BV(MOTOR3_B);
latch_tx();
initPWM(3, freq);
break;
case 4:
latch_state &= ~_BV(MOTOR4_A) & ~_BV(MOTOR4_B);
latch_tx();
initPWM(4, freq);
break;
}
}
int motorMap [] = {MOTOR_1_PWM, MOTOR_2_PWM};
void setPWM(uint8_t num, int freq)
{
softPwmWrite (motorMap [num], freq) ;
}
void initPWM(uint8_t num, int freq)
{
softPwmCreate (motorMap [num], 0, RANGE) ;
setPWM(num, freq);
}
void DCMotorRun(uint8_t motornum, uint8_t cmd)
{
uint8_t a, b;
switch (motornum)
{
case 1:
a = MOTOR1_A; b = MOTOR1_B;
break;
case 2:
a = MOTOR2_A; b = MOTOR2_B;
break;
case 3:
a = MOTOR3_A; b = MOTOR3_B;
break;
case 4:
a = MOTOR4_A; b = MOTOR4_B;
break;
default:
return;
}
switch (cmd)
{
case FORWARD:
latch_state |= _BV(a);
latch_state &= ~_BV(b);
latch_tx();
break;
case BACKWARD:
latch_state &= ~_BV(a);
latch_state |= _BV(b);
latch_tx();
break;
case RELEASE:
latch_state &= ~_BV(a);
latch_state &= ~_BV(b);
latch_tx();
break;
}
}
void DCMotorSetSpeed(uint8_t motornum, int speed)
{
switch (motornum)
{
case 1:
setPWM(1, speed);
break;
case 2:
setPWM(2, speed);
break;
case 3:
setPWM(3, speed);
break;
case 4:
setPWM(4, speed);
break;
}
}
int main ()
{
int i, j ;
if (wiringPiSetup () == -1)
{
fprintf (stdout, "oops: %s\n", strerror (errno)) ;
return 1 ;
}
for (i = 0 ; i < NUM_MOTORS ; ++i)
{
softPwmCreate (motorMap [i], 0, RANGE) ;
}
// Bring all up in stages 25%, 50%, 75% 100%
for (j = 25 ; j <= RANGE ; j+=25)
{
printf("pwm %d%%\n", j);
for (i = 0 ; i < NUM_MOTORS ; ++i)
{
softPwmWrite (motorMap [i], j) ;
}
delay(6000);
}
// Bring all up in stages 25%, 50%, 75% 100%
for (j = RANGE-25 ; j >= 0; j-=25)
{
printf("pwm %d%%\n", j);
for (i = 0 ; i < NUM_MOTORS ; ++i)
{
softPwmWrite (motorMap [i], j) ;
}
delay(6000);
}
return 0;
}Code: Select all
#include <stdio.h>
#include <errno.h>
#include <string.h>
#include <wiringPi.h>
#include <softPwm.h>
typedef unsigned char uint8_t;
#define _BV(bit) (1 << (bit))
#define MOTORLATCH 0
#define MOTORCLK 1
#define MOTORENABLE 2
#define MOTORDATA 3
#define MOTOR_1_PWM 4
#define MOTOR_2_PWM 5
#define MOTOR1_A 2
#define MOTOR1_B 3
#define MOTOR2_A 1
#define MOTOR2_B 4
#define MOTOR4_A 0
#define MOTOR4_B 6
#define MOTOR3_A 5
#define MOTOR3_B 7
#define FORWARD 1
#define BACKWARD 2
#define BRAKE 3
#define RELEASE 4
static unsigned char latch_state;
void latch_tx(void)
{
unsigned char i;
digitalWrite(MOTORLATCH, LOW);
digitalWrite(MOTORDATA, LOW);
for (i=0; i<8; i++)
{
digitalWrite(MOTORCLK, LOW);
if (latch_state & _BV(7-i))
{
digitalWrite(MOTORDATA, HIGH);
}
else
{
digitalWrite(MOTORDATA, LOW);
}
digitalWrite(MOTORCLK, HIGH);
}
digitalWrite(MOTORLATCH, HIGH);
}
void enable(void)
{
pinMode(MOTORLATCH, OUTPUT);
pinMode(MOTORENABLE, OUTPUT);
pinMode(MOTORDATA, OUTPUT);
pinMode(MOTORCLK, OUTPUT);
latch_state = 0;
latch_tx();
digitalWrite(MOTORENABLE, LOW);
}
void DCMotorInit(uint8_t num)
{
switch (num)
{
case 1:
latch_state &= ~_BV(MOTOR1_A) & ~_BV(MOTOR1_B);
latch_tx();
break;
case 2:
latch_state &= ~_BV(MOTOR2_A) & ~_BV(MOTOR2_B);
latch_tx();
break;
case 3:
latch_state &= ~_BV(MOTOR3_A) & ~_BV(MOTOR3_B);
latch_tx();
break;
case 4:
latch_state &= ~_BV(MOTOR4_A) & ~_BV(MOTOR4_B);
latch_tx();
break;
}
}
void DCMotorRun(uint8_t motornum, uint8_t cmd)
{
uint8_t a, b;
switch (motornum)
{
case 1:
a = MOTOR1_A; b = MOTOR1_B;
break;
case 2:
a = MOTOR2_A; b = MOTOR2_B;
break;
case 3:
a = MOTOR3_A; b = MOTOR3_B;
break;
case 4:
a = MOTOR4_A; b = MOTOR4_B;
break;
default:
return;
}
switch (cmd)
{
case FORWARD:
latch_state |= _BV(a);
latch_state &= ~_BV(b);
latch_tx();
break;
case BACKWARD:
latch_state &= ~_BV(a);
latch_state |= _BV(b);
latch_tx();
break;
case RELEASE:
latch_state &= ~_BV(a);
latch_state &= ~_BV(b);
latch_tx();
break;
}
}
int main ()
{
int i, j ;
if (wiringPiSetup () == -1)
{
fprintf (stdout, "oops: %s\n", strerror (errno)) ;
return 1 ;
}
pinMode(MOTOR_1_PWM, OUTPUT);
pinMode(MOTOR_2_PWM, OUTPUT);
digitalWrite(MOTOR_1_PWM, 0);
digitalWrite(MOTOR_2_PWM, 0);
enable();
DCMotorInit(1);
DCMotorInit(2);
DCMotorRun(1, FORWARD);
digitalWrite(MOTOR_1_PWM, 1);
sleep(1);
DCMotorRun(1, RELEASE);
sleep(1);
DCMotorRun(1, BACKWARD);
sleep(1);
DCMotorRun(1, RELEASE);
sleep(1);
DCMotorRun(2, FORWARD);
digitalWrite(MOTOR_2_PWM, 1);
sleep(1);
DCMotorRun(2, RELEASE);
sleep(1);
DCMotorRun(2, BACKWARD);
sleep(1);
DCMotorRun(2, RELEASE);
sleep(1);
}
Code: Select all
MOTORLATCH D12 YELLOW 0 P1-11
MOTORCLK D4 GREEN 1 P1-12
MOTORENABLE D7 BROWN 2 P1-13
MOTORDATA D8 PINK 3 P1-15
MOTOR1 PWM D11 WHITE 4 P1-16
MOTOR2 PWM D3 BLUE 5 P1-18
MOTOR3 PWM D5
MOTOR4 PWM D6
Those are geared motors. They're not very powerful, but still require a fair amount of current to start. Same thing happened to me with two 12V 1A geared motors. They worked fine connected to 10 AA NiMH in series, but not once all the cabling and a couple of used relays were in place. With exactly the same symptom: just a tick, no power. New relays and proper cabling did the job.cbis wrote:The motors are part of the sainsmart 4x4 car built to go with the motor shield I'm using..
