QTouch on MCU and Extension Boards

Xplained boards with devices containing a build-in PTC module should try to overload the Table 1 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 1. Recommended Priority for PTC Signals on One Header Boards (EXT1)
Pin number EXT1	MCU board	Extension board	Recommendation
3	Y-line 1	Y-line 1	1^st priority for QTouch Y-lines
4	Y-line 2	Y-line 2	2^nd priority for QTouch Y-lines
5	Y-line 3	Y-line 3	3^rd priority for QTouch Y-lines
6	Y-line 4	Y-line 4	4^th priority for QTouch Y-lines
7	X-line 1	X-line 1	1^st priority for QTouch X-lines
8	X-line 2	X-line 2	2^nd priority for QTouch X-lines
9	X-line 3 (Y-line 5)	X-line 3	3^rd priority for QTouch X-lines
10	X-line 4 (Y-line 6)	X-line 4	4^th 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. Recommended Priority for PTC Signals on Two Header Boards (EXT1)
Pin number on EXT1	MCU board	Extension board	Recommendation
3	Y-line 1	Y-line 1	1^st priority for QTouch Y-lines
4	Y-line 2	Y-line 2	2^nd priority for QTouch Y-lines
5	Y-line 3	Y-line 3	3^rd priority for QTouch Y-lines
6	Y-line 4	Y-line 4	4^th priority for QTouch Y-lines
7	(X-line 5)	X-line 1 duplicated	5^th priority for QTouch X-lines
8	(X-line 6)	X-line 2 duplicated	6^th priority for QTouch X-lines
9	Y-line 5 (X-line 7)	Y-line 5 or X-line 3 duplicated	5^th priority for QTouch Y-lines (Use XY capable lines if possible for supporting one header boards)
10	Y-line 6 (X-line 8)	Y-line 6 or X-line 4 duplicated	6^th priority for QTouch Y-lines (Use XY capable lines if possible for supporting one header boards)
11
12
13
14
15
16	Y-line 7	Y-line 7	7^th priority for QTouch Y-lines
17
18	Y-line 8	Y-line 8	8^th priority for QTouch X-lines

Table 3. Recommended Priority for PTC Signals on Two Header Boards (EXT2)
Pin number on EXT2	MCU board	Extension board	Recommendation
3	X-line 1	X-line 1	1^st priority for QTouch X-lines
4	X-line 2	X-line 2	2^nd priority for QTouch X-lines
5	X-line 3	X-line 3	3^rd priority for QTouch X-lines
6	X-line 4	X-line 4	4^th priority for QTouch X-lines
7	X-line 9	X-line 5	9^th priority for QTouch X-lines
8	X-line 10	X-line 6	10^th priority for QTouch X-lines
9	X-line 11	X-line 7	11^th priority for QTouch X-lines
10	X-line 12	X-line 8	12^th priority for QTouch X-lines
11
12
13
14
15
16
17
18