On our custom LPC54018 board, we need to use simultaneously 6 uart channels.
Our modem runs at 115,200 BPS and I am getting FIFO receive overflow errors and losing characters in the modem initialization stage. Since the modem response in not a constant length, I need to get an interrupt for every incoming character (In the interrupt I empty the rx buffer in any case). I tried disabling all other uart channels but I am still getting the overflow errors. I tried changing the watermark from kUSART_RxFifo1 to kUSART_RxFifo8, setting the uart interrupt priority to 3, using BOARD_BootClockFROHF96M() and also BOARD_BootClockPLL180M(), without resolving the problem. I can see that the modem's CTS line is low but also tried without using it.
I tried directly using the uart interrupt with my own ring buffer and also using the uart driver with its ring buffer.
I have already looked at the SDK uart examples.
Anyone can help or see a problem in the attached code?