82K pullup, the I2C signals will take fooooreeeeeveeeer to transition from low to high.
Be ready to really lower the bus speed with that.
Got a spec on the NXT?
There is no 10K resistor internally or on the board. See the schematic for the A4/SDA & A5/SCL lines.http://arduino.cc/en/uploads/Main/Arduino_Uno_Rev3-schematic.pdf
From the ATMega32 spec with a couple of things >> emphasized <<.
The 2-wire Serial Interface (TWI) is ideally suited for typical microcontroller applications. The
TWI protocol allows the systems designer to interconnect up to 128 different devices using only
two bi-directional bus lines, one for clock (SCL) and one for data (SDA).
>>The only external hardwareneeded to implement the bus is a single pull-up resistor for each of the TWI bus lines. <<
All devices connected to the bus have individual addresses, and mechanisms for resolving bus
contention are inherent in the TWI protocol.
As depicted in Figure 22-1,
>>both bus lines are connected to the positive supply voltage through pull-up resistors. <<
>> The bus drivers of all TWI-compliant devices are open-drain or open-collector.<<
This implements a wired-AND function which is essential to the operation of the interface. A low
level on a TWI bus line is generated when one or more TWI devices output a zero. A high level
is output when all TWI devices tri-state their outputs,
>>allowing the pull-up resistors to pull the line high. <<
Note that all AVR devices connected to the TWI bus must be powered in order to allow any
The number of devices that can be connected to the bus is only limited by the bus capacitance
limit of 400 pF and the 7-bit slave address space. A detailed specification of the electrical characteristics
of the TWI is given in ”Two-wire Serial Interface Characteristics” on page 327. Two
different sets of specifications are presented there, one relevant for bus speeds below 100kHz,
and one valid for bus speeds up to 400kHz.
4.7K is usually spec'ed for pullups. 2.2K for long wires. You can see the rising signal really degrade with a 10K pullup.