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@felmue said in Some questions...:

Hello @ajb2k3

I think you might still be thinking about the wrong module. (I know it's a bit confusing as both these modules are listed on the specs page.)

The Stepmotor Driver Module (HR8825) uses an TCA9554 and not an STM32. So no open source firmware as far as I can see.

Thanks
Felix

I think you may be thinking of the servo module as the ones I have and the product title shows AATMEGA328

the 13.2 uses the STM32

@schlabbermampf said in Making a Robot: USB-C -> ATOM -> 2x SERVO2 ?:

@ajb2k3 yes makes sense, thats what the SERVO2 module shop-description says, i just get it to understand slowly ;D (just discovered the Documentation of all the M5 parts!) since i like to use the 360° servos with speed and direction control via PWM it may be possible to ensure (in software) a limit for the applied power in total.

Looks like bridging the 30 pin MBus over some short distance with a cable is kinda overkill so a single stack it shall be.

Power management strongly depends on what the servos have to lift, so overall weight-balance/efficiency of all parts is what its all about then in the long term (even when plugged into a full power source).

So i want to get my hands on these pieces soon and start digging. happy to share some progress here :D
Thanks for your kind and fast replies :D

edit: here is the stack, quite simple. (hope these servos do not fry to soon):

You will need to add a 200ms wait at the end of the program loop (or was it 500ms) to slow down the command transmissions otherwise they will fry (I have learned that the hard way after killing 3!)

As @felmue stated, the battery packs will not power the servos, the servos will only be powered from the external supply. If you try, the Fire will suffer from "Brown outs" and keep resetting when more then a few try to operate.

@felmue said in Some questions...:

Hello @ajb2k3

correct, but @NilZ was asking about the Stepmotor Driver Module (HR8825). Or did I miss something?

Thanks
Felix

Ahh, I sread the 13.2 on the bottom line and thought that was what he was asking about.
However, the firmware is available here: https://github.com/m5stack/stepmotor_module/tree/master/Firmware for stepmotor module/GRBL-Arduino-Library
and you can change the address in grblmain.cpp by editing

#define I2C_ADDR 0x73

to

#define I2C_ADDR 0x71

or any other available i2c address and the address is handled by the atmega328 controller.

@felmue said in Some questions...:

Hello @NilZ

1. apart from the M5Stack color (white vs. black) there is no difference - you can double-check that yourself as for both the schematic link is the same.
2. yes
3. no, the I2C address is fixed to 0x27. There are no dip switches or solder pads to change the I2C address I can see. That said, in the schematic you'll see that the chip doing I2C has three address pins but they are all tied to VCC.

Thanks
Felix

The GRBL has a set of dip switches that are used to change the I2c address from 0x70 to 0x71

https://docs.m5stack.com/en/module/grbl13.2

1 - None,
2 - Yes,
3 - Yes, if you change the I2c address on one unit, you can use both for 6 axis but you will need to add an external supply to only one module as the power will be passed through the MBUS.

The Atoms are not directly compatible as the bases and modules are 54X54mm and use the 30 pin MBus where as the atom is only 20x20mm and uses the Atom expansion port.

That said the modules communicate using I2C and can be driven but you would need to alter the I2C address of each module to use have separate address and separate power supplies as 24 servos will cause brownouts (I get brownouts with only 6 servos if I don't use a separate power supply. If you change the I2c address' they can be stacked together and use only one external power supply.

I wrote a guide on using two servos with 1 grove port here:
https://www.hackster.io/AJB2K3/2-servos-1-grove-port-9fe6ea

This is what I wanted to try but I don't have a printer yet.

@bram the stamp Pico uses the esp32 Pico D3 the Stamp C uses the ESP32 C3 which is a RiscV processor

unless the block is stacked together. else you can't remove or select them at the same time.