Hi everybody.
I'm fairly new to Arduino and this is my first post in the forum so I hope I'm in the right category.
I am working on my fist bigger project, which will be a robot arm with 4-6 Servos but have run into problems when trying to get my set up working with even one servo.
I have tried several different libraries, examples from said libraries, code & tutorials from different online sources and I've read just about everything I can find on the PCA9685 but to no avail.
For some reason I can't get any servo to move with any code I use or any slot I plug it into, but I did figure out that the communication with the board works and that there is a Voltage on the PCA9685'S pins by using the "PWMtest" Example from the Adafruits PWM Servo Library.
I got an LED to fade up and down and I can measure a voltage on all pins that's fading up and down like it's supposed to. When I use servos and the servo example or any other code I write / find it doesn't work.
I have re-wired everything several times to make sure I didn't mess up anywhere and I have tested this with several different MG995 Servos and with a SG90 Micro Servo to make sure those are not the issue.
I have attached a picture of my circuit and one showing a voltage measurement at the power terminal of the PCA.
At first I thought my power supply might be the issue, but it's delivering the exact voltage i set on the buck converter to the power terminal on the PCA9685. I have set the buck converter to 5V as well as 6V (which is the recommended voltage for the MG995) and the current is limited to about 1.5 Amps for testing with one Servo right now but I can increase it to about 6 Amps if I need to, based on my power supply.
I tried to use the small SG90 Servo and power it straight from the Arduino by connecting V+ on the PCA to the 5V pin on Arduino,but it doesn't work either. (And yes I have only tried this with 1 micro servo to test and I'm aware you can't power servos of the Arduino).
I also ran an I2C Scan and it finds a device at the standard address of 0x40 and as stated above I can apparently send signals to the PCA since the LED experiment works.
I am using:
Arduino Uno R3
PCA9685
XL4016 Buck Converter
Power Supply with Output of 19.5 V, 6.7 A max.
I will be using MG995 Servos for the final Arm but I also have a SG90 micro servo which I've used to test as well, same results
Here is the PWMtest code that makes an LED fade up and down successfully:
/***************************************************
This is an example for our Adafruit 16-channel PWM & Servo driver
PWM test - this will drive 16 PWMs in a 'wave'
Pick one up today in the adafruit shop!
------> http://www.adafruit.com/products/815
These displays use I2C to communicate, 2 pins are required to
interface. For Arduino UNOs, thats SCL -> Analog 5, SDA -> Analog 4
Adafruit invests time and resources providing this open source code,
please support Adafruit and open-source hardware by purchasing
products from Adafruit!
Written by Limor Fried/Ladyada for Adafruit Industries.
BSD license, all text above must be included in any redistribution
****************************************************/
#include <Wire.h>
#include <Adafruit_PWMServoDriver.h>
// called this way, it uses the default address 0x40
Adafruit_PWMServoDriver pwm = Adafruit_PWMServoDriver();
// you can also call it with a different address you want
//Adafruit_PWMServoDriver pwm = Adafruit_PWMServoDriver(0x41);
#if defined(ARDUINO_ARCH_SAMD)
// for Zero, output on USB Serial console, remove line below if using programming port to program the Zero!
#define Serial SerialUSB
#endif
void setup() {
#ifdef ESP8266
Wire.pins(2, 14); // ESP8266 can use any two pins, such as SDA to #2 and SCL to #14
#endif
Serial.begin(9600);
Serial.println("16 channel PWM test!");
pwm.begin();
pwm.setPWMFreq(1600); // This is the maximum PWM frequency
// if you want to really speed stuff up, you can go into 'fast 400khz I2C' mode
// some i2c devices dont like this so much so if you're sharing the bus, watch
// out for this!
#ifdef TWBR
// save I2C bitrate
uint8_t twbrbackup = TWBR;
// must be changed after calling Wire.begin() (inside pwm.begin())
TWBR = 12; // upgrade to 400KHz!
#endif
}
void loop() {
// Drive each PWM in a 'wave'
for (uint16_t i=0; i<4096; i += 8) {
#ifdef ESP8266
yield();
#endif
for (uint8_t pwmnum=0; pwmnum < 16; pwmnum++) {
pwm.setPWM(pwmnum, 0, (i + (4096/16)*pwmnum) % 4096 );
}
}
}
Here is (one of) the example codes i tried to use, which doesn't work for me:
/***************************************************
This is an example for our Adafruit 16-channel PWM & Servo driver
Servo test - this will drive 16 servos, one after the other
Pick one up today in the adafruit shop!
------> http://www.adafruit.com/products/815
These displays use I2C to communicate, 2 pins are required to
interface. For Arduino UNOs, thats SCL -> Analog 5, SDA -> Analog 4
Adafruit invests time and resources providing this open source code,
please support Adafruit and open-source hardware by purchasing
products from Adafruit!
Written by Limor Fried/Ladyada for Adafruit Industries.
BSD license, all text above must be included in any redistribution
****************************************************/
#include <Wire.h>
#include <Adafruit_PWMServoDriver.h>
// called this way, it uses the default address 0x40
Adafruit_PWMServoDriver pwm = Adafruit_PWMServoDriver();
// you can also call it with a different address you want
//Adafruit_PWMServoDriver pwm = Adafruit_PWMServoDriver(0x41);
// Depending on your servo make, the pulse width min and max may vary, you
// want these to be as small/large as possible without hitting the hard stop
// for max range. You'll have to tweak them as necessary to match the servos you
// have!
#define SERVOMIN 150 // this is the 'minimum' pulse length count (out of 4096)
#define SERVOMAX 600 // this is the 'maximum' pulse length count (out of 4096)
// our servo # counter
uint8_t servonum = 0;
void setup() {
Serial.begin(9600);
Serial.println("16 channel Servo test!");
pwm.begin();
pwm.setPWMFreq(50); // Analog servos run at ~60 Hz updates
yield();
}
// you can use this function if you'd like to set the pulse length in seconds
// e.g. setServoPulse(0, 0.001) is a ~1 millisecond pulse width. its not precise!
void setServoPulse(uint8_t n, double pulse) {
double pulselength;
pulselength = 1000000; // 1,000,000 us per second
pulselength /= 50; // 50 Hz
Serial.print(pulselength); Serial.println(" us per period");
pulselength /= 4096; // 12 bits of resolution
Serial.print(pulselength); Serial.println(" us per bit");
pulse *= 1000;
pulse /= pulselength;
Serial.println(pulse);
pwm.setPWM(n, 0, pulse);
}
void loop() {
// Drive each servo one at a time
Serial.println(servonum);
for (uint16_t pulselen = SERVOMIN; pulselen < SERVOMAX; pulselen++) {
pwm.setPWM(servonum, 0, pulselen);
}
delay(500);
for (uint16_t pulselen = SERVOMAX; pulselen > SERVOMIN; pulselen--) {
pwm.setPWM(servonum, 0, pulselen);
}
delay(500);
servonum ++;
if (servonum > 7) servonum = 0;
}
I hope someone can help me because after days of googeling and experimenting I'm stuck.
If you need any additional information, let me know.
Thanks a lot in advance 
