PIC32MX675F256H

uart tx issue.c

#include <p32xxxx.h>
#include <stdint.h>
#include <sys/kmem.h>

uint8_t  __attribute__((coherent)) buf[200];

void main()
{
    
    uint32_t i;
    for(i = 0;i<200;i++)
    {
        buf[i] = 65;
    }
    
    // Configure BAUD rate
    U1BRG = 4; //4 Mbps assuming an 80Mhz PB clock
    U1MODESET = 1 << _U1AMODE_BRGH_POSITION; // BRGH = 1
    //U1ASTAbits.UTXISEL = 1;
    U1MODESET = 1 << _U1AMODE_ON_POSITION; // Enable UART
    U1STASET = 1 << _U1STA_UTXEN_POSITION; // TX enabled
    
    IFS0bits.U1TXIF = 0;
    
    DMACONSET = 0x8000; //Enable DMA
    DCH0SSA = KVA_TO_PA(&buf); // Source Address
    DCH0SSIZ  = 200; //Source size
    DCH0DSIZ = 1; // Destination size
    DCH0CSIZ = 1; //Cell Size
    DCH0ECONbits.CHSIRQ = _UART1_TX_IRQ;
    DCH0ECONSET = 16; //UART IRQ & enable IRQ cell trigger
    DCH0DSA = KVA_TO_PA(&U1TXREG); // Destination Address

    DCH0CONSET  = 0x80; //Enable DMA Channel
    
    while(1)
    {}
}