The data sheet for LPC81x defines pin 19 "In ISP mode, this is the USART0 receive pin U0_RXD.
In boundary scan mode: TDO (Test Data Out)"
But the schematic of LPC812MAX target RX is connected to pin 18.
What are the correct pins to connect the ISP UART to?
I don't know where is the misunderstanding but both schematic and datasheet are correct.
I checked datasheet, U0_RXD is pin 19
In ISP mode, pin PIO0_0 is connected to function U0_RXD and pin PIO0_4 is connected to function U0_TXD on the USART0 block.
In LPC812 MAX board, the connection is the same as schematic.
Have a nice day,