I2C controller without sensor.

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yzfoot
 
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I2C controller without sensor.

Post by yzfoot »

Searching for a standalone I2C controller but not finding. . I understand there are copious sensors of all sort with I2C connections but that is not what I want. I want an I2C interface that I can add my own devices to. Is there not such a chip ? I look at I2C devices I have and don't see such a chip. Is that function accomplished some other way ? Enlightenment of any sort appreciated.

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Re: I2C controller without sensor.

Post by adafruit_support_bill »

It depends on what you want to control. We use the PCA9685 as an i2c interface/control chip for many of our DC/Stepper motor control boards. The PWM outputs of the PCA9685 are used to control the dual H-Bridge motor driver chips.

The MCP23017 is used as an i2c interface/control chip for our character LCD boards.

If your devices have analog interfaces, you can use an i2c ADC/DAC like the PCF8591.

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Re: I2C controller without sensor.

Post by adafruit_support_carter »

I2C is generally a (very common) peripheral of the microcontroller. What devices are you working with?
I want an I2C interface that I can add my own devices to.
What does "own devices" refer to here?

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Re: I2C controller without sensor.

Post by dastels »

I2C support is generally incorporated into microcontrollers.

There are chips to add I2C capabilities to CPUs/MCUs that don't contain an I2C interface. E.g. https://www.nxp.com/products/interfaces ... er:PCF8584.

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Re: I2C controller without sensor.

Post by yzfoot »

I don't want to add I2C to an MCU that doesn't have it, found a chip that does that. I want to connect a micro controller that has I2C to this new device that provides I2C connectivity. On the other side of that new device is/are my "own devices". Currently I'd like that to be a small bank of user input switches, in the future maybe the digital side of an ADC, or who knows what might be desired later. The key is I2C connectivity with whatever the market doesn't then provide as a sensor. I know many many things now provide I2C connectivity, probably even those that I called out but not everything imaginable so one might want to 'roll their own' and when that comes up I'd like to be prepared.

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Re: I2C controller without sensor.

Post by dastels »

AH. In that case I'll second Bill and suggest the MCP23017: 2 8-bit digital port, each bit can be input or output with option pullups.

I've used it A LOT. E.g. https://learn.adafruit.com/digital-circ ... m-emulator That's the only published project.

Another approach is SeeSaw https://learn.adafruit.com/adafruit-see ... 9-breakout, which is a configurable I2C interface.

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Re: I2C controller without sensor.

Post by yzfoot »

I looked at the PCA9685, seems the controllable pins are all outputs, filed for later.
MCP23017 Looks promising !
PCF8591 Looks good for analog only use

Thanks for the info, I think this is what I was looking for, very much appreciated.

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Re: I2C controller without sensor.

Post by yzfoot »

MCP23008 on order due tomorrow. While waiting I looked more at your seesaw device, that's pretty much what I had envisioned when I started this search. I see in the docs references to both the SAMD09 and ATTiny8x7 micro controllers. Is the seesaw available with my choice of micro controllers ? I also notice the docs are from 2017. Maybe thing have evolved.

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Re: I2C controller without sensor.

Post by dastels »

I'm not sure about that, but it *is* a nice platform, and the firmware is easy enough to customize... mostly just fiddling with the config file.

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Re: I2C controller without sensor.

Post by adafruit_support_carter »

The SAMD09 based seesaw was the original - along with a few other SAMD variants. The ATTiny8x7 seesaw is newer and created due to supply issues obtaining SAMD processors. But the ATTiny8x7 was written to the original c2017 SAMD seesaw spec.

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Re: I2C controller without sensor.

Post by yzfoot »

Thanks again. Informative as usual from Adafriut !

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