Firmware implementation

AN2927

10/12

Figure 11 shows an example where there is a small amount of noise and some

measurements are rejected (i.e. r1 and r2).

In this example, the burst group 3 (BG3) is repeated until all measurements within this group

pass. More time is required for a complete acquisition.

Figure 11.

Example 2

Figure 12 shows an example where there is a lot of noise and the maximum limit (i.e. 20) is

reached. In this case, the complete electrode acquisition is rejected.

In this example, the maximum number of rejected measurements is reached and the

acquisition is stopped on that electrode.

Figure 12.

Example 3

Note:

The maximum number of rejected measurements is set in the configuration file of the ST

touch sensing library.

Calculation of Min/Max limits

measurement of each burst group. This multiplication factor is set inside the configuration

each burst group is always “Pass”. In case the first measurement is “incorrect”, and the

consecutive ones are “correct”, the burst group will still be determined “Fail”.

Acquisition OK

BG1

Pass

BG3

Fail

BG2

Pass

BG4

Pass

BG3

Fail

BG3

Pass

Remaining measurements

are skipped

r1

r2

Start

Acquisition stopped

BG1

Pass

BG2

Fail

BG2

Fail

BG3

Fail (max.)

BG2

Pass

BG3

Fail

Start

r1

r2

r3

r21