capsense definitions

emalund · ‎2017-09-21

Posted on September 21, 2017 at 18:54

how are capsense pins defined, e.g. TSC_GROUP4_IO1 does not correlate.

also any links to capsense info beyond AN4310 would be appreciated

emalund · ‎2017-09-21

Posted on September 21, 2017 at 19:20

I am tasked with modifying something that has two 'finger caps' attached to PB 13 & 14, in the software they are described as group6_io3 and group 6_io4 which correlates bitwise to PB 10&11. something does not make sense

Vangelis Fortounas · ‎2017-09-21

Posted on September 21, 2017 at 19:22

hello!

Try

http://www.stmicroelectronics.com.cn/content/ccc/resource/technical/document/user_manual/84/34/0d/e0/46/36/4c/f5/DM00210526.pdf/files/DM00210526.pdf/jcr:content/translations/en.DM00210526.pdf

document.

Regards

vf

emalund · ‎2017-09-21

Posted on September 21, 2017 at 21:05

thanks, with that link and the reference manual page 810 I have gotten where the 'finger cap' is defined, not very intuitive, but oh well. What I still can't find is the pin definition for the sampling cap. since I have to totally revise the capsense, I need to figure this out.

waclawek.jan · ‎2017-09-21

Posted on September 22, 2017 at 00:30

Hi Erik,

I don't use the TSC module and you did not tell us which chip are you using, but according to 'L4x5/4x6 RM you select the pins used for sampling capacitor in the TSC_IOSCR register.

The signals numbers (Gx_IOy) are converted to physical pin number through the Alternate Function table from the respective datasheet, but you've probably figured that out already.

Jan

emalund · ‎2017-09-22

Posted on September 22, 2017 at 14:35

Hi, Jan it's been a while

sorry I tell everybody to mention the chip and forget myself it is STM32F091

The signals numbers (Gx_IOy) are converted to physical pin number through the Alternate Function table from the respective datasheet

true for button pins, false for capacitor pins

Vangelis Fortounas · ‎2017-09-22

Posted on September 22, 2017 at 15:06

Hello !

true for button pins, false for capacitor pins

As

Waclawek.Jan

mentioned above, TSC_IOSCR reg assigns the sampl. capacitor bit to external pins through AF.

Rgrds

vf

waclawek.jan · ‎2017-09-22

Posted on September 22, 2017 at 15:45

Erik,

This is the mapping of physical pins to Gx_IOy, from the DS, for Group 6 (into which fall both your ''fingers''):

My understanding of TSC based on reading of RM0091 is, that

- during one ''normal'' conversion, only one ''channel'' or ''electrode'' (which is one of your ''fingers'') input is used per group, selected by setting one bit in TSC_IOCCR, respective to this input

- there is one ''capacitor'' or ''sampling'' input per group, selected by setting one bit in TSC_IOSCR (note that ST is kind enough to provide several names for the same functionality, keeping us alert while reading 😉 )

- in your case, as you have two ''fingers'', you have to perform two separate conversions, swapping the ''channel'' between them (i.e. rewriting TSC_IOCCR)

So, you have to connect your sampling capacitor to PB11 or PB12 and set the according bit in TSC_IOSCR.

I repeat that I have never used TSC just reread the RM chapter a couple of times.

JW