47.7.3.4.1 Transfer Size

Depending on the data size to transmit, from 8 to 16 bits, the PDC manages automatically the type of pointer size it has to point to. The PDC performs the following transfer, depending on the mode and number of bits per data.

• Fixed mode:
  • 8-bit data:
1-byte transfer, PDC pointer address = address + 1 byte,
PDC counter = counter - 1
  • 9-bit to 16-bit data:
2-byte transfer. n-bit data transfer with don’t care data (MSB) filled with 0’s,
PDC pointer address = address + 2 bytes,
PDC counter = counter - 1
• Variable mode:
  • In Variable mode, PDC pointer address = address + 4 bytes and PDC counter = counter - 1 for 8 to 16-bit transfer size.
  • When using the PDC, the TDRE and RDRF flags are handled by the PDC. The user’s application does not have to check these bits. Only End of RX Buffer (ENDRX), End of TX Buffer (ENDTX), Buffer Full (RXBUFF), TX Buffer Empty (TXBUFE) are significant. For further details about the Peripheral DMA Controller and user interface, refer to the “Peripheral DMA Controller (PDC)” section.