The LPC845 has dedicated OD outputs on PIO10 & 11. They have a high-current mode, but this appears to be available only if the respective PIO registers have been set to Fast-mode Plus I2C. I want to use the sink capability (which is obviously on the chip) in GPIO mode, but this does not appear to be available: I2CMODE = 0 = Standard Mode or Fast Mode I2C; I2CMODE = 1 = Standard GPIO w/OD; I2CMODE = 2 = Fast Mode Plus I2C; I2CMODE = 3 = Reserved.
Looking at the bits, it looks like a value of 3 would be high-power GPIO, but does anyone know?
This is what I have found, on UM11029 11.4.6 I2C-bus mode, "The I2C-bus pins PIO0_10 and PIO0_11 can be programmed to support a true open-drain mode independently of whether the I2C function is selected or another digital function."
Please read the complete paragraph to see all the information, let me know if you have another question.
Best Regards, Miguel.