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Hi, I have noticed an issue in a bare-metal application when polling the register XUARTPS_ISR (Channel Interrupt Status Register). No issues when I use XUART_SR (Channel Status Register) instead. The issue: When I poll XUART_ISR for TX_FULL and RX_EMPTY the UART interface becomes an unstable state. No sending and receiving after a few bytes is possible. Has somebody noticed the same issue or can somebody explain whats happening? Edit: My current code for the UART interface (Here I use XUARTPS_SR instead. But when I poll XUARTPS_ISR (0x14) it doesn't work.): #include <string.h> #include <dev/io.h> #define UART0_BASE 0xE0000000 #define UART1_BASE 0xE0001000 #define UART_CR_OFFSET 0x0 #define UART_CR_RXRST 0 #define UART_CR_TXRST 1 #define UART_CR_RXEN 2 #define UART_CR_RXDIS 3 #define UART_CR_TXEN 4 #define UART_CR_TXDIS 5 #define UART_MR_OFFSET 0x4 #define UART_IER_OFFSET 0x8 #define UART_BGEN_OFFSET 0x18 #define UART_SR_OFFSET 0x2C #define UART_SR_RXEMPT 1 #define UART_SR_RXFULL 2 #define UART_SR_TXEMPT 3 #define UART_SR_TXFULL 4 #define UART_FIFO_OFFSET 0x30 #define UART_BDIV_OFFSET 0x34 struct uart_reg { unsigned int cr; unsigned int mr; unsigned int ier; unsigned int bgen; unsigned int sr; unsigned int fifo; unsigned int bdiv; }; static struct uart_reg regs; void uart_init(void) { unsigned int tmp; regs.cr = (UART1_BASE + UART_CR_OFFSET); regs.mr = (UART1_BASE + UART_MR_OFFSET); regs.ier = (UART1_BASE + UART_IER_OFFSET); regs.bgen = (UART1_BASE + UART_BGEN_OFFSET); regs.sr = (UART1_BASE + UART_SR_OFFSET); regs.fifo = (UART1_BASE + UART_FIFO_OFFSET); regs.bdiv = (UART1_BASE + UART_BDIV_OFFSET); /* Check if RX/TX is enabled */ tmp = io_rd32(regs.cr); /* Skip init if RX/TX enabled */ if (tmp & ((1 << UART_CR_TXEN) | (1 << UART_CR_RXEN))) return; /* Reset RX/TX paths */ tmp = io_rd32(regs.cr); tmp |= ((1 << UART_CR_TXRST) | (1 << UART_CR_RXRST)); io_wr32(regs.cr, tmp); do tmp = io_rd32(regs.cr); while (tmp & ((1 << UART_CR_TXRST) | (1 << UART_CR_RXRST))); /* Set baudrate to 115200; UART Reference Clock: 100MHz */ io_wr32(regs.bgen, 124); io_wr32(regs.bdiv, 6); /* Set mode: 8 Databit, 1 Stopbit, No Parity */ io_wr32(regs.mr, 0x20); /* Enable RX/TX */ tmp = io_rd32(regs.cr); tmp &= ~((1 << UART_CR_TXEN) | (1 << UART_CR_RXEN)); io_wr32(regs.cr, tmp); } int uart_send(unsigned char *buf, int len) { int i; unsigned int tmp; for (i = 0; i < len; i++) { do tmp = io_rd32(regs.sr); while (tmp & (1 << UART_SR_TXFULL)); io_wr08(regs.fifo, buf[i]); } return len; } int uart_recv(unsigned char *buf, int len) { int i; int ret = 0; unsigned int tmp; tmp = io_rd32(regs.sr); if (tmp & (1 << UART_SR_RXEMPT)) return 0; for (i = 0; i < len; i++) { buf[i] = io_rd08(regs.fifo); ret++; tmp = io_rd32(regs.sr); if (tmp & (1 << UART_SR_RXEMPT)) return ret; } return ret; }

Greetings all, I am new to zedboard. This might be a basic question. I want to send some data via UART0 to DDR memory through direct memory access AXI. (GPS data) Again I want to collect another set of data from UART1 and writing it to DDR memory.(GSM/LTE module) Now if interrupt from one UART( UART1) occurs, I want the processed data of UART0 which is on the DDR memory to be read via UART1(GSM module) and send to a remote server. Any suggestions and advice on how can i design the hardware?