Content originally posted in LPCWare by mc on Sat Nov 16 11:19:00 MST 2013
Hi MAUROFIUNER,
As Mike mentioned boot ROM samples ISP pin at power on. Once BootROM detects this pin low, LPC1769 execute ISP mode(ROM code). Therefore LPC1769 is not executing user code. At that time LPC1769 takes command from UART0 serial port only. Please check LPC17xx User manual paragraph 2, section 32.3, page 615/840 UM10360 Rev. 2 — 19 August 2010 details about ISP pin condition.
Hope it is helpful.
MC