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TSC Group1 unexpected behavior STM32L552ZE

CDan.1
Associate II

Hi,

I have designed a keypad with 11 touchkey's. For this I have used TSC group 1,3,4 and 6. As FW i have used the STM32_TouchSensing_Library and I have a problem. All groups are working ok, sensing touch corectlyexcept group 1. This group has the sampleing cap on the other side of the package (PC3 IO4) and the other 3 chanels on the other side (PB12, 13, 14). From this group I always get the max count interrupt when i acticate the acq. The thing is I always get the max value that i set (EX: 1FFF or 3FFF-16383). I have checked and double checked the configuartion of the pins, the configuration of the TSC before ACQ and it is ok. I have also measured the pins and what i have noticed is that on the sampeling cap (pin PC3 and GND) I do not have a puls like on the other sampeling caps, for the other groups. If I configure the pins as output the pin works ok. Could there be any other reason for this channel to not work, anything that I missed a special setting or something? I have tested the FW on another fresh PCB and I get the same result all channel work except the channels from group1.

Update.

I have converted one of the channel from group 1 in sample pin (G1_IO1) and left pin G1_IO4 as a channel. After I did this the other 2 channles in the goup (G1_IO2 and G1_IO3) started workking ok with G1_IO1 as sampeling channel. But G1_IO4 still dose not work, From my point of view seems to be something with channel G1_IO4 (PC3), could there be other settings that need to be done or what could it be? The package that I am using is STM32l552ZET6.

Any help is greatly appreciated.

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