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Pro Trinket Tachometer using 5V ItsyBitsy 32u4
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Pro Trinket Tachometer using 5V ItsyBitsy 32u4

by stanleytpig on Sat Aug 17, 2019 5:42 pm

Hello, I am attempting to build a “Pro Trinket Tachometer” following instructions on your website (https://learn.adafruit.com/pro-trinket- ... uit-design); however, I am substituting the 5V ItsyBitsy 32u4 for the Pro Trinket. I have a couple of questions; 1) Can I use the same pins identified for the Pro Trinket on the ItsyBitsy, meaning are A3, A4, and 3 on Pro Trinket the same as A3, A4 and 3 on the ItsyBitsy? From the ItsyBitsy pinout it looks like logic pins 2 and 3 are for I2C – I am very confused. Also, it appears that ItsyBitsy logic pin 3 does not have a pullup resistor.

Well I’m guessing that on the ItsyBitsy I should use logic pin #2 as I2C data pin, pin #3 as the I2C clock pin – is this correct and do I need pull-up resistors for I2C? Lastly, on the ItsyBitsy can I use logic pin #4 as the sensor input from the Reflective IR Sensor and will I need to use a pullup resistor? Any assistance you can provide would be greatly appreciated. Thanks.

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Re: Pro Trinket Tachometer using 5V ItsyBitsy 32u4

by adafruit_support_bill on Sun Aug 18, 2019 8:02 am

1) Can I use the same pins identified for the Pro Trinket on the ItsyBitsy

The pinouts of the 32U4 for both interrupts and the i2c bus are different. You need to use Pins 2 and 3 for SDA and SCL. Pullups are not necessary if you are using one of our display boards.

That leaves pins 0, 1 and 7 as options for the interrupt input. All pins have internal pullups that can be enabled via pinmode.

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Re: Pro Trinket Tachometer using 5V ItsyBitsy 32u4

by stanleytpig on Sun Aug 18, 2019 2:38 pm

that is perfect - thanks very much.

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