Im making a system where I'm using all the above mentioned interrupts. I have had the TC0, PWM and the ADC running nicely until now, but when I add the UART0 the TC0 goes dead (it's running a 1 Khz clock) I want the UART0 to give me interrupts when it receives a byte and only when that occours. When I send data I don't want to receive any interrupts (It's a Master/Slave configuration where I send som commands and the remote unit answers) I have configured TC0 at Vic slot 0, the ADC at 1 and now the UART0 at 2. I've read some posts that could indicate that all those interrupts might not work together. On the other hand, it could be my init or ISR that is wrong ... My init and ISR for the UART0 is as follows: void UART::init() { PINSEL0 |= 0x000000005; // Enable RxD0 and TxD0 U0LCR = 0x03; // 8 bits, no Parity, 1 Stop bit U0IER = 0; // Disable UART0 RX setBaudRate(9600); // 9600 Baud Rate @ 15MHz VPB Clock VICVectAddr2 = (unsigned long)UART_ISR; VICVectCntl2 = 0x20 | 6; /* UART1 Interrupt */ VICIntEnable = 1 << 6; /* Enable UART1 Interrupt */ U0FCR = 0x07; // Enable FIFOs and reset them U0IER = 1; // Enable UART0 RX uint32_t dummy = U0IIR; // Read IrqID - Required to Get Interrupts Started } void UART::setBaudRate(uint32_t baudRate) { uint32_t DLreload; //Hardcoded to 15 MHz PClk (VPBDIV = 0x0) DLreload = static_cast<uint32_t>((15000000u / baudRate) / 16u); U0LCR |= 0x80; /* Set DLAB */ U0DLL = DLreload; U0DLM = (DLreload >> ; U0LCR &= ~0x80; /* Clear DLAB */ } void UART_ISR(void) { uint8_t interruptMask = U0LSR; //Also resets interrupts in LSR uint8_t IIR = U0IIR; //Active low if((IIR & 0x1) == 0) { //Data ready in RxBuffer if((IIR & 0x04) != 0) { if(!(interruptMask & 0x01)) { uint8_t byte = U0RBR; //Handle byte ...... } } } // Acknowledge interrupt in VIC VICVectAddr = 0u; }