Hi all Does any one know why PORT0.27 at LPC1768 is open drain?when i add external 10k pull up resistor then this pin work properly but when i remove external resistor it doesnt work and for example if i apply high level via LPC_GPIO0->FIOSET|=(1<<27); then this pin goes to 0.3volt instead of 3.3volt and when apply low level via LPC_GPIO0->FIOCLR|=(1<<27); it goes to 0 volt. I enable chip pull up resistor on this pin but it seems doesnt work.What should i do?
www.nxp.com/.../UM10360.pdf [2] Pins P0[27] and P0[28] are open-drain for I2C-bus compliance.
>>I enable chip pull up resistor on this pin but it seems doesnt work.What should i do? Reading the manual and catching the nuances is what most of us try to do before going to board design.