ML51/ML54/ML56
Sep. 01, 2020
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ML51/M
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Series
Tec
hnical Reference
Manual
threshold control for each channel can be pre-determined in TKHTHx registers, x denotes adjacent
channels
’ number, for example, TKHTH0.
TKIFx is set if TKDATx is greater than TKHTHx. TKDATx greater than TKHTHx means a potential key
touch occurs. As shown in Figure 6.19-4 Touch Key Controller Interrupt Modes For Threshold Control.
TKHTHx
scan
TKIFx
Figure 6.19-4 Touch Key Controller Interrupt Modes For Threshold Control.
Low Power Consumption Solution
6.19.5.8
Non-stop key scanning in a low power system can be easily achieved. User can use RTC to wake-up
Touch Key controller for key scanning periodically. Touch Key controller requests
HIRC
for key
scanning only when waked-up, and keeps CPU in power-down state. Interrupts generated when a
potential key scanning event occurs, otherwise, Touch Key controller will terminate key scanning
without interrupt and makes itself in power down state.
Wake-up by Key Touch / Release
To enable threshold control for interrupt generation, system keeps in low power until any potential key
touch/release detected.
Wake-up by Any Key Touch
To save system more power consumption, user can use Any Key Wake-up function by setting
SCAN_ALL (TKCON0[3]). All channels enabled but not assigned as reference channel are scanned,
and scanning data is valid in TKDATALL. The CCBDALL may be different from normal and need to
be calibrated individually. Proximity detection is also achievable by using this mode.