UART and XBee and NIOS II

[Altera_Forum]

Hello,  

 I need help. Based on my intensive internet search, all I need to connect to an Zigbee network using the FPGA (NIOS II) is a UART.  Here are my queries:  (1) Can I use IORD_ALTERA_AVALON_UART_RXDATA(UART_BASE) to recieve the data from the XBee module, and in return, using IOWR_ALTERA_AVALON_UART_TXDATA(UART_BASE, data) to transmit the data?  If yes to (1), what should I be receiving.  I have created an integer array for the receive data: int uart_rx[1024] for each rx request, see code below:  int i = 0;  while(1) {  if ( IORD_ALTERA_AVALON_UART_STATUS(UART1_BASE) && 0XE0 )  {  uart_rx[i] = IORD_ALTERA_AVALON_UART_RXDATA(UART_BASE);  i++;  } }   The array are filled with a bunch of numbers, my second question is, what I am receving?  Thank you.

[Altera_Forum]

You're nearly there... 

 Assuming you're right regarding the requirements of your Zigbee interface (I don't KNOW that is what it requires, but believe it is) then 'Yes' to (1) - you can use the commands you've identified to communicate with a UART peripheral connected to a Nios processor.  However, I think you're code isn't quite what you want.  You've correctly identified that you need to test the UART's 'STATUS' register. I assume you're intending to test whether there is a new receive character in the receive buffer. However, for that your bit mask and AND operator are incorrect.  When a new character is available in the 'RXDATA' register, the 'rrdy' bit is set in the 'STATUS' register. That is bit 7 of the 'STATUS'.  So you need to test if(IORD_ALTERA_AVALON_UART_STATUS(UART1_BASE) & 0X80) to establish whether there is a valid character in the receive buffer.  Your current test is testing the status of 3 bits of the 'STATUS' register - transmit empty, transmit ready & receive char ready. I'm not sure why you would want to test those three bits at the same time.