16.11 Example Setup Code

This code example illustrates using DMA1 to transfer 10 bytes of data from 0x1000 in Flash memory to the UART transmit buffer.

void initializeDMA(){
//Select DMA1 by setting DMASELECT register to 0x00
    DMASELECT = 0x00;
//DMAnCON1 - DPTR remains, Source Memory Region PFM, SPTR increments, SSTP
    DMAnCON1 = 0x0B;
//Source registers
//Source size
    DMAnSSZH = 0x00;
    DMAnSSZL = 0x0A;
//Source start address, 0x1000
    DMAnSSAU = 0x00;
    DMAnSSAH = 0x10;
    DMAnSSAL = 0x00;
//Destination registers
//Destination size
    DMAnDSZH = 0x00;
    DMAnDSZL = 0x01;
//Destination start address, 
    DMAnDSA = &U1TXB;
//Start trigger source U1TX. Refer the datasheet for the correct code 
    DMAnSIRQ = 0xnn;
//Change arbiter priority if needed and perform lock operation
    DMA1PR = 0x01;        // Change the priority only if needed
    PRLOCK = 0x55;            // This sequence 
    PRLOCK = 0xAA;            // is mandatory 
    PRLOCKbits.PRLOCKED = 1;  // for DMA operation
//Enable the DMA & the trigger to start DMA transfer
    DMAnCON0 = 0xC0;