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Describe your issue:
I have successfully attached an MPU-9520/6500 board to my Raspberry Pi 3B+, however I have noticed some possible errors in the documentation on this page
The 10KOhm MPU resistor is in parallel with the Pis 1K8 resistor gives a pull up of roughly 1K5 which is above the 9KOhm shown the TI example. So perfectly acceptable, in fact should give slightly better performance as the rise times will be lower.
Not sure if this is the correct category for documentation moderators please move if necessary.
Yes, your board maybe but in the zoo of the available boards, this is not guaranteed.
Since the MPU can work from anywhere between 2.4 V and 3.6 V VCC, it is the safest bet to recommend going with 3.3 V.
Typically some LDO regulator is used and if you have a drop-out of 0.3 V then the remaining 3.0 V are still sufficient to drive the IC.
Connecting 5 V without a LDO regulator is a sure way to kill it.
The description should stay as it is regarding this point.
I cannot comment on this one, but I would guess this hint comes from practical experience.
I would guess that this is rather applicable to connecting the board to an RPi Pico as it does NOT have the internal pullups and thus the 10 K may be too high.
Otherwise the wording would not make any sense since adding additional resistors in parallel would further reduce the overall resistance and should exactly NOT be applicable to the regular RPis with their internal pull-up.
Fair point on the LDO I’m not that familiar with them and thought they would not output any voltage. Rather than just not regulating.
I wasn’t suggesting making 5V the only option just adding a note that on some boards there maybe a voltage regulator. The Fritzing diagram clearly shows a board with an LDO …
E.g. Add “Some MPU-9250 breakout boards contain a 3V3 Regulator this could be bypassed when using the 3V3 supply from the Pi.”
Could the comment on 10K pull up resistors be moved to the section relating to the Pico? Its current at the top where the MPU-9250 is introduced.
e.g. change
“The Pico does not include any built-in I2C pull-up resistors.”
To
“The Pico does not include any built-in I2C pull-up resistors. Some MPU accelerometer modules include pull-ups, but some are too large at 10K and must be changed or supplemented by smaller parallel resistors.”
As you have now noticed yourself, just being able to “spot” a LDO regulator on such a board is not sufficient, one should also be able to assess the impact and if it makes a difference.
To make things even worse, there are boards with level shifters on them. If you connect such to 5 V you will also have 5 V as logic levels and this typically will destroy your RPi.
To keep things simple, I’m not a fan of mentioning details that do not make a real life difference. Use 3V3 and you will be on the safe side without knowing the gory details of each single board.
Seems to make sense to me. Feel free to raise a PR.