uart1 of 2136?

Started by Jack Key August 2, 2006
Hi. I am using UART1 along with UART0, Timer 0, I2C1, SPI1 on my LPC2136 board. My problem is that when I write a byte to U1THR, it gets transmitted and the interrupt is set. In the interrupt, I send another byte which also gets sent, but I dont get any further interrupt for U1THR empty.
One possible thing is that the interrupt may not be getting reset, but I transmitted the value of U1IIR through UART0, which shows 0xC1, which means fifos are enabled and no interrupt is pending.
What could be the reason for me not getting any further interrupt. My UART1 settings are as follows:
1. FIFOs enabled.
2. Transmit and receive interrupt enabled.
3. No parity, one stop bit, 8-bit word length
4. The last step of UART1 initialization, which is never called again, is clearing of the DLAB bit.
5. I have enabled UART1 interrupt. It is as IRQ with 4th highest priority.
Just for your information:
Highest priority - unused (reserved for USB, when I shift to 2148)
second highest priority - timer 0 interrupt
thirt highest priority - unused (UART0, but disabled later)
fourth highest priority - UART1
fifth highest priority - I2C1
Kindly help me.

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An Engineer's Guide to the LPC2100 Series