Specifications

dsPIC33F Family Reference Manual

When scanning is used, and no simultaneous sampling is performed (SIMSAM = 0), SMPI<3:0>

should be set to one less than the number of inputs being scanned. For example, if CHPS<1:0>

= 00 (only one Sample/Hold channel is used), and AD1CSSL = 0xFFFF, indicating that

AN0-AN15 are being scanned, then set SMPI<3:0> = 1111 so that the internal pointer is incre-

mented only after every 16th sample/conversion sequence. This avoids unused locations in the

blocks corresponding to the analog inputs being scanned.

Similarly, if ALTS=1, indicating that alternating analog input selections are used, then SMPI<3:0>

is set to ‘0001’, thereby incrementing the internal pointer after every 2nd sample.

Note: The module does not perform limit checks on the generated buffer addresses. For

example, you must ensure that the LS bits of the DMAxSTA or DMAxSTB register

used are indeed ‘0’. Also, the number of potential analog inputs multiplied by the

buffer size specified by DMABL<2:0> must not exceed the total length of the DMA

buffer.