Hi Guys, I am struggling to get a PCA9685 I2C PWM module to work on a Nucleo_F446ZE board - my first venture into I2C in this world, and the PCA9685 is new to me. Using MBed Studio. I did get the servo working using PWMOut, so I think servo and board are working okay. The PCA9685 module is untest…

This was my code that now works on both my modules. It sweeps each servo in a sine wave pattern at 1Hz frequency. Each servo’s sine wave is shifted by 22.5 degrees (360/16) from it’s neighbour, so servo 0 and servo 7 are synchronised, but 180 degrees phase-shifted. // test PCA9685 module with s…

I thought I found something with setPWMFrequency, but it looks ok. sleep_for(chrono::milliseconds(5)) can be simplified to: sleep_for(5ms) The appendix ms is a predefied literal. But that is not the problem.

Thanks for the help. That bit of code that sets the prescale value was copied from Paolo Sanna’s class, and I did have a good look at it in conjunction with the part of the manual that deals with setting the PWM frequency, and I think it is correct. Here :- uint8_t newmode = (oldmode & 0x7F) | 0x…

have you compared your methods to adafruit/Adafruit-PWM-Servo-Driver-Library/blob/master/Adafruit_PWMServoDriver.cpp /*! * @file Adafruit_PWMServoDriver.cpp * * @mainpage Adafruit 16-channel PWM & Servo driver * * @section intro_sec Introduction * * This is a library for t…

Yup - I saw that writing bit 7 does nothing :grinning: On the module I am using the ~OE pin has a pullup (or is it pulldown with the line above it?) resistor on the board, so the board doc says it can be left open. But I will double check. Not sure who made the module. No-Name from Bangood probably…

Tied the ~OE down - Didn’t help. Sherlock Holmes said: “Once you have removed the impossible, what remains, no matter how improbable, must be the truth.” :grinning: I am starting to think it may be the module. But I will sharpen the code and diagnostic pencil just a little more. Plan B is anothe…

Yes, I have seen a pull down in the Adafruit documentation too. Seems to be true. I’m also interested in the PCA9685 for dimming a bunch of LED spots. So I have ordered two modules for testing, they should arrive on friday and I can join the game also.

I see some mosfets and gamma correction tables in your future. :grinning: // Gamma brightness lookup table <https://victornpb.github.io/gamma-table-generator> // gamma = 2.00 steps = 100 range = 0-100 const uint8_t gamma_lut[100] = { 0, 0, 0, 0, 0, 0, 0, 0, 1, 1, 1, 1, 1, 2, 2, 2, 3, 3, 3, 4, 4, 4,…

Thanks! I have played with LED dimming several years ago, and found also the exponential intensity curve. It was calculated by some Excel sheet to create a table for the AVR. But now I will use also a STM32F4, and this guy has enough power and resources to calc a dimming curve on the fly, otherwise…

Whew! I am still not winning here. Still no wiggling in my servo-farm. I wrote a function (setClearBitInRegister) to allow me to set or clear individual bits in the PCA9685’s registers so I can make my code look a little bit more like the user manual. It does a read-modify-write. Then I wrote a li…

today, I received my PCA9685 module. Connected also some old servo and tried your code, also nothing. I checked the I2C communication with my Saleae logic analyzer, I2C looked fine. Conneted the LA to the PWM0 pin, and it worked! So in my case it was just a broken cord in the servo cable. Another …

Issues with PCA9685 module on Nucleo_F446ZE, MBed 6.0

Electronics and hardware

JojoS (Johannes Stratmann) August 15, 2020, 5:28pm 18

Thanks for feedback and the solution for the puzzle
And I know the rough climate in SA, I’ve been in some places there, lovely country.

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Issues with PCA9685 module on Nucleo_F446ZE, MBed 6.0

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