> For the complete documentation index, see [llms.txt](https://diamondsystems.gitbook.io/user-manuals/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://diamondsystems.gitbook.io/user-manuals/sbcs/helios/hardware-user-manual/16.performing-an-a-d-conversion/16.4-select-the-polarity.md).

# 16.4 Select the Polarity

Select the polarity from among the available options in the table in section 15.2. If the polarity is the same as for the previous A/D conversion it does not need to be set again. Write this setting along with the singleended/differential setting to the register at page 2 base+13. To access page 2, the page must be set with the page register at base+1. 

outp(base+1, 2);                  // set page 

outp(base+13, 0x00);          // example: sets bipolar, single-ended 

outp(base+13, 0x08);         // example: sets unipolar, single-ended