Sensor scan time depends on the hardware scan time and the sensor initialization time.
Hardware scan time = (2^N - 1)/ Mod clock
Sensor initialization is the time required to setup the widget before starting to scan.
When there are several widgets in the design, the setup time is increased. If you have all the sensors in the one widget, then the widget set up time is reduced.
If possible you can have a single widget for all the 10 sensors, provided you get similar signal from all the sensors.
According to my observation Scan time in Method 2 is greater than the scan time in Method 1
This is not expected. Can you let us know how you are measuring scan time?
Thanks BragadeeshV_41 for the reply.
I have went through one query in cypress community in which you have suggested that capsense buttons(more then 1) must be of same dimension in order to give them under one widget.
Actually in my project all button buttons are not of same dimension, so we get different signal value. So according to my understanding I can't keep all sensors under one widget. Am I correct?
Correct me if I am wrong.
I am measuring sensor scan time from the following path
In this it gave me the total scan time for all the widgets.
Associate Engineer, Embedded Common
L&T TECHNOLOGY SERVICES LIMITED
L3 Building, Manyata Embassy Business park
Nagawara Hobli, Bengaluru-560045
If buttons that have different Cp are grouped together under one widget then each button might produce different signal since they have the same hardware and threshold parameters. If the touch performance is good, you can use it like that.
You need to set sense clock such that it charges and discharges the sensor with max Cp in that widget. You can use SmartSense to determine the sense clock frequency.
Hardware scan time is not the actual scan time as mentioned in the previous response. It involves the sensor initialization time also. This needs to be taken into account. For example toggle a gpio pin before and after the CapSense_ScanAllWidgets() and CapSense_ProcessAllWidgets to know the actual scan time/ processing time.
If needed, you can try using low level CapSense APIs for reduced execution time by scanning/ processing only specific widgets according to your application using CapSense_ProcessWidgetExt() , CapSense_CSDSetupWidget and CapSense_Scan().
If you want to further reduce the scan time, you may have to reduce the Cp of the sensor by:
1. Connecting hatch to shield
2. Reducing trace length
3. Reducing button diameter