2.5.2.2 QTouch on MCU and Extension Boards

Xplained boards with devices containing a build-in PTC module should try to overload the Table 2-3 functions with QTouch® lines to make it compatible with the QTouch extension boards.

QTouch Design of Small Boards

For small extensions with only one header (EXT1), four Y- and four X-lines are the maximum of touchlines that can be expected to be available for compatibility for the series of small MCU boards. Both the MCU and the extension board should be designed with this rule set.

For compatibility with some of the first extension boards Y-lines noted in parentheses might optionally be implemented on the MCU board, but this should only be done with XY-capable QTouch lines for (Y-line 5 and 6).

Table 2-5. Recommended Priority for PTC Signals on One Header Boards (EXT1)
Pin number EXT1MCU boardExtension boardRecommendation
3Y-line 1Y-line 11st priority for QTouch Y-lines
4Y-line 2Y-line 22nd priority for QTouch Y-lines
5Y-line 3Y-line 33rd priority for QTouch Y-lines
6Y-line 4Y-line 44th priority for QTouch Y-lines
7X-line 1X-line 11st priority for QTouch X-lines
8X-line 2X-line 22nd priority for QTouch X-lines
9X-line 3 (Y-line 5)X-line 33rd priority for QTouch X-lines
10X-line 4 (Y-line 6)X-line 44th priority for QTouch X-lines
11
12
13
14
15
16(Y-line 7)
17
18(Y-line 8)

QTouch Design of Medium and Large Boards

For medium QTouch extension boards with header EXT1 and EXT2, only the four first lines on each header should be used to ensure compatibility with most MCU boards.

If more than four Y-lines are required on the extension kit, use the ones marked in the table with the loss of compatibility with one or more MCU board. If four or less Y-lines are required, duplicate the four first X-lines from the EXT2 header on the EXT1 header to make it compatible with small MCU boards.

MCU boards should be designed with the minimum of four Y-lines on EXT1 and four X-lines on EXT2. For compatibility with the QT1 Xplained Pro board, Y-lines 5-8 can optionally be designed in. For compatibility to small extension boards, XY-lines should be designed in on pin 7-10.

Table 2-6. Recommended Priority for PTC Signals on Two Header Boards (EXT1)
Pin number on EXT1MCU boardExtension boardRecommendation
3Y-line 1Y-line 11st priority for QTouch Y-lines
4Y-line 2Y-line 22nd priority for QTouch Y-lines
5Y-line 3Y-line 33rd priority for QTouch Y-lines
6Y-line 4Y-line 44th priority for QTouch Y-lines
7(X-line 5)X-line 1 duplicated5th priority for QTouch X-lines
8(X-line 6)X-line 2 duplicated6th priority for QTouch X-lines
9Y-line 5 (X-line 7)Y-line 5 or X-line 3 duplicated5th priority for QTouch Y-lines (Use XY capable lines if possible for supporting one header boards)
10Y-line 6 (X-line 8)Y-line 6 or X-line 4 duplicated6th priority for QTouch Y-lines (Use XY capable lines if possible for supporting one header boards)
11
12
13
14
15
16Y-line 7Y-line 77th priority for QTouch Y-lines
17
18Y-line 8Y-line 88th priority for QTouch X-lines
Table 2-7. Recommended Priority for PTC Signals on Two Header Boards (EXT2)
Pin number on EXT2MCU boardExtension boardRecommendation
3X-line 1X-line 11st priority for QTouch X-lines
4X-line 2X-line 22nd priority for QTouch X-lines
5X-line 3X-line 33rd priority for QTouch X-lines
6X-line 4X-line 44th priority for QTouch X-lines
7X-line 9X-line 59th priority for QTouch X-lines
8X-line 10X-line 610th priority for QTouch X-lines
9X-line 11X-line 711th priority for QTouch X-lines
10X-line 12X-line 812th priority for QTouch X-lines
11
12
13
14
15
16
17
18