LPC1227 GPIO pins Reset Value Causing Problems

Discussion created by lpcware Employee on Jun 15, 2016
Latest reply on Jun 15, 2016 by lpcware
Content originally posted in LPCWare by th_shak on Mon Jan 28 13:18:29 MST 2013
According to the datasheet of LPC1227 all IO pins are set to digital mode with pull-ups enabled at reset. This causes very serious problems. If we have some leds connected to GPIO pins they will light at reset, or even worst, if we have a step-up circuit connected directly to a GPIO pin it will "fry" since we are in reset, it will go high and without any control from the software the produced voltage will climb to "thousands" of volts. What is this silly mistake you have done and how we can overcome it without connecting external pull-down resistors to the "critical" pins? You could set the reset value to Open Drain mode! :mad:(These are not theoretical assumptions, but facts that I have tested and I'm 100% sure that are happening exactly as I'm saying).