I am building a dev board based on LPC2103. I am having some problem with the ROM bootloader: I can autobaud, but almost any command would cause it to autobaud again at a different baudrate, and no actual bootloader access is possible. The USB to serial chip is a STM32F042F4P6 programmed with a USB to serial firmware, and that MCU has access to P0.14 and RESET lines beside UART0.
What is causing this problem? The chips has date code 1209. (I bought it back in 2014, but allowed it to sit in my parts bin for a few years before finally came up with the project.)
Do you have like a schematic on how this has been done? have measure the clock of the LPC2103 to warranty it is stabilize once the boot it is assure by the USB to UART.