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I2C address 0x30 is unchangeable #3

cax opened this issue Oct 29, 2017 · 7 comments


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commented Oct 29, 2017

By hardware design, the motor shield allows selecting one of four i2c addresses (0x2d, 0x2e, 0x2f , 0x30) by soldering connection between relevant pads (AD0, AD1) on the shield.

At the moment, the alternative firmware has 0x30 as a hard-coded address, which does not allow using of more then one shield in the project.

There are 2 possible solutions I can think of:

  1. re-implement the pad-soldering address selection feature

  2. compile and publish 4 different firmware binaries, each for different hard-coded i2c address from the 0x2d-0x30 range.
    Shield users will choose the address and flash the relevant firmware bin file.

It should be easy for you, as you already have the compilation toolchain installed.
Thank you in advance!


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commented Oct 31, 2017

Here are the lines from the original firmware source code that may be helpful:

#define AD0_Pin GPIO_PIN_0
#define AD0_GPIO_Port GPIOF
#define AD1_Pin GPIO_PIN_1
#define AD1_GPIO_Port GPIOF

uint8_t i2c_base_add=0x2d;
uint8_t ad0_val,ad1_val;




hi2c1.Init.OwnAddress1 = i2c_base_add<<1;


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commented Nov 1, 2017

I had no patience, so I installed the toolchain, patched the value of 0x60 (2 * 0x30) in main.c to suit addresses 0x2d, 0x2e, 0x2f , 0x30, compiled firmware for each address, flashed and tested with motor shield.

Now it's possible to use more than one motor shield at once.

Attached is the zip with firmware files for 4 different addresses.


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commented Nov 8, 2017

I was looking for this so bad and had no idea how to "install the toolchain". Thank you so much for this.. testing it now!


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commented Nov 22, 2017

I have a branch to fix the firmware to use the solder pads on the back here:
I will test it when I get time, which should be by the weekend. It builds on #6 so if we can get that one reviewed first then it will speed up incorporation of the next PR once I've done the testing.


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commented Jan 18, 2018

I'm interested by the firmware fix, but I see that the merge request upon which it builds has been closed. What is the status of this branch? Has it been tested?


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commented Aug 11, 2018

Please check this PR to address this issue


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commented Aug 12, 2018

Solved, thank you danielfmo for your help.

@pbugalski pbugalski closed this Aug 12, 2018

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