If all you have is 20K resistors you may want to try putting 2-4 of them in parallel for each of the two I2C lines this will put your pullups in the range of 5K (4 resistors in parallel) to 10K (2 resistors in parallel). 20K is a bit weak for an I2C pullup. You may also want to take a look at the information in this TI publication on I2C pullup resistor calculations: www.ti.com/.../slva689.pdf
↧