Hi!
I've have a setup where I have I2C bus range extender to control IO Pi Plus from the distance of 30m. The I2C range extender has it own power and it provides +5V, ground, SCL and SDA pins, nothing else. I noticed that this poses a problem as the +3.3V is missing and I2C level converter seems to depends on it. I solved this by building voltage divider to feed also +3.3V from the +5V.
My question is: Have you thought that future versions of IO Pi Plus could have voltage divider built in, so users could only power the board via +5V, ground, SCL and SDA pins? Or am I missing something here?
If you or anyone is interested, I'm using this range extender: https://shop.controleverything.com/products/long-distance-i2c-bus-extender
Seems like these are bit hard to find from Europe. Maybe AB Electronics could build one of their own in the future :)
Powering IO Pi Plus
2083 Views - Created 26/08/2017
26/08/2017
Posted by:
jayden
27/08/2017
Posted by:
andrew
Location:
United Kingdom
Hi
The 3.3V bus on the IO Pi Plus is only needed to set the I2C pins to the same voltage as the Raspberry Pi GPIO, the 3.3V side of the level translator should work with anything between 2V to 5V. Looking at the specs for your range extender it works at 5V for the extended side of the I2C bus so you should be able to get away with bridging the 3.3V and 5V pins on the IO Pi Plus.
We will have a look at adding a voltage divider or at least the pads to add one for the 3.3V bus on the next revision of the board and I will have a look into designing our own I2C range extender.
The 3.3V bus on the IO Pi Plus is only needed to set the I2C pins to the same voltage as the Raspberry Pi GPIO, the 3.3V side of the level translator should work with anything between 2V to 5V. Looking at the specs for your range extender it works at 5V for the extended side of the I2C bus so you should be able to get away with bridging the 3.3V and 5V pins on the IO Pi Plus.
We will have a look at adding a voltage divider or at least the pads to add one for the 3.3V bus on the next revision of the board and I will have a look into designing our own I2C range extender.
08/09/2017
Posted by:
jayden
Just confirming: So you're saying that at the far end of the Raspberry, beyond extender, I can use 5V also for the 3.3V pin to make it work?
08/09/2017
Posted by:
andrew
Location:
United Kingdom
It may be worth measuring the voltage on the two I2C pins next to the 3.3V pin on the IO Pi Plus to make sure they are at 5V but if they are then you can use 5V for the 3.3V pin.
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