Problems Communicating with Adafruit PCA9685

Robotics & Edge Computing Jetson & Embedded Systems Jetson AGX Xavier
1

Hello All,

I am planning on controlling an RC car motor and servo (Traxxas 2075) using the PCA9685 servo driver, and a traxxas ESC. (The driver is powered by a 4 x AA battery pack) I have connected my driver to the Xavier as follows (Bus 1):

GND Pin 6 → Servo Driver (GND)
VCC Pin 2 → Servo Driver (VCC – 5V)
SDA Pin 27 → Servo Driver (SDA)
SCL Pin 28 → Servo Driver (SCL)

But whenever I run the command

sudo i2cdetect -y -r 1

I get this result:
https://imgur.com/a/v69Glc6

And everytime I try to run the example file from JetsonHacks (https://github.com/jetsonhacks/JHPWMDriver) I receive the error:

PCA9685 Write Byte error: 121PCA9685

Any ideas on why it is not connecting?

Thanks, Luke

EDIT
My mistake, I had the address set to 0x40 in this line:

PCA9685 *pca9685 = new PCA9685(0x40);

When the servo was actually connected at address 0x70.
Problem solved.

2

Good to know you resolved the problem, and looking forward to see your project video sharing in forum.
Thanks.

3

Hi, I am having the same problem as you.
Can you explain what you did to solve it ?
sudo i2cdetect -y -r 1
[sudo] password for prophet:
0 1 2 3 4 5 6 7 8 9 a b c d e f
00: – – – – – UU – – – – – – –
10: – – – – – – – – – – – – – – – –
20: – – – – – – – – – – – – – – – –
30: – – – – – – – – – – – – – – – –
40: UU UU – – – – – – – – – – – – – –
50: – – – – – – – – – – – – – – – –
60: – – – – – – – – – – – – – – – –
70: – – – – 74 – – –
prophet@prophet-desktop:~$

or this
sudo i2cdetect -y -r 0
0 1 2 3 4 5 6 7 8 9 a b c d e f
00: – – – – – – – – – – – – –
10: – – – – – – – – – – – – – – – –
20: – – – – – – – – – – – – – – – –
30: – – – – – – – – – – – – – – – –
40: – – – – – – – – – – – – – – – –
50: 50 – – – – – 56 – – – – – – – – –
60: – – – – – – – – – – – – – – – –
70: – – – – – – – –

4

hello cespedesk

is there still an issue to communicate with Adafruit PCA9685?
may I also have your confirmation that which platform you’re working with?

since you’d also report an issue on Nano platform here: Topic 75767,
however, you’d confirmed it works in Topic 146769.
thanks

5

I don’t know how but the servos are working, looks like my numbers are just diferent but it connected.Thanks.