I'm having trouble finding the answer for this. If I have two analog devices, LCD and 3 axis accelerometer in my case, if the aref is effectively at 5v can I still read the 3.3v from the 3axis accurately? Or, can I set aref to 3.3v and still have the 5v LCD (backpack i2c) work on a4 and a5?
Thanks!
Analog 3v3 and 5v together?
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Re: Analog 3v3 and 5v together?
i you mean the analog lcd is using the i2c? Anyway what you can do is use a voltage divider to divide that 3.3v peak gyro output down to 1.1v then use the internal analog reference on the arduino. This will help you get more bits from the ADC... Otherwise with a 5v reference you'll only have about 650/1024 points on the adc.
That shouldn't be a problem with the I2c, but all your analog pins will max out at 1.1v input so be careful. You'll probably want someone else to agree with me before trying it
That shouldn't be a problem with the I2c, but all your analog pins will max out at 1.1v input so be careful. You'll probably want someone else to agree with me before trying it
- baldengineer
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Re: Analog 3v3 and 5v together?
AREF has no bearing on I2C. In fact, when I2C is enabled, a separate open-collector driver is used. This is why pull-ups on I2C are used.sbrooke wrote: Or, can I set aref to 3.3v and still have the 5v LCD (backpack i2c) work on a4 and a5?
A LCD isn't an analog device.sbrooke wrote:
If I have two analog devices, LCD and 3 axis accelerometer in my case, if the aref is effectively at 5v can I still read the 3.3v from the 3axis accurately?
So there's no reason you couldn't set AREF to 3V3 and drive your LCD.
Please be positive and constructive with your questions and comments.