Actual max number of Haptic Controllers that can be connecte

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johnk0000
 
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Actual max number of Haptic Controllers that can be connecte

Post by johnk0000 »

Hi, I am in the middle of my first haptic project and I have set up several test beard boards with haptic controllers on them. I have a main breadboard with 9 x Haptic Controllers that are all jump cabled together and I can get them all to work (with short wires). I also have several feather boards (mounted on separate half-breadboards) that I am connecting to the bank of haptic controllers

Right now I'm using Feather 32u4 Bluefruit LE running arduino, and I can push the code to the board (from the haptic headband guide) with 9 Haptic actuators and everything works as expected. I also have a single Haptic Controller on the half-breadboard alongside the feather. I have that test Haptic Actuator there so I can easily verify that the feather is working on that single Haptic Controller

My issue is that when I connect the single test Haptic Controller in-line (on I2C) with the other 9 Haptic Controllers (for a total of 10), it doesn't work anymore. The behavior of the haptic actuators is that there is a buzz when the script would normally launch, then they cut out for about 5 seconds, and the cycle repeats. I am thinking that there might be some software that is crashing and then there is a reloading and a restart before repeating the cycle. I do not think it is a power issue as the vibrations are plenty strong with 9 and the little vibration that comes when you try to run 10 seems to be the same power level. I have not tried to connect more than 10 Haptic Controllers

If this is a software issue, is there any way we could see a remedy that would increase the total number of actuators that can be addressed on an I2C bus?

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adafruit_support_bill
 
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Re: Actual max number of Haptic Controllers that can be conn

Post by adafruit_support_bill »

The DRV2605 has a fixed i2c address of 0x5A. You can put multiples of them on the bus if you want them all to act the same. If you want to address them individually, then you would need something like an i2c multiplexer.https://www.adafruit.com/product/2717

As for why 9 work but 10 do not, it could be a power issue, a bus loading issue, or a combination of both. The cyclic-reset nature of the symptoms indicates a llikely power issue. The startup current spike for the motors may be causing a short-term 'brownout' sufficient to cause the processor to reset. How are you powering all this?

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johnk0000
 
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Re: Actual max number of Haptic Controllers that can be conn

Post by johnk0000 »

Ok I'll pick up the multiplexer, that should solve the addressing issue

With regard to the power, I am a bit of a novice, what would the best way to run power directly to the Haptic Controllers be? Ideally they are fully powered

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Re: Actual max number of Haptic Controllers that can be conn

Post by adafruit_support_bill »

With regard to the power, I am a bit of a novice, what would the best way to run power directly to the Haptic Controllers be? Ideally they are fully powered
First you need to estimate your power requirements and pick a power supply that meets or (preferably) exceeds those requirements.

If you are using the vibrator motors from the store, they draw about 66mA each at 3.3v in normal operation. But the startup current is probably close to twice that. For 10 motors, a 1A supply should be plenty for normal operation. But you would need around 1.32A or more to handle the surge if they are all starting at once.

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