STM32L0 TSC Analog Switch

[Diego Ballen]

Posted on November 17, 2017 at 17:36

Hello everyone,

I was researching about the TSC (Touch Sensing Controller) of my Board Nucleo L053R8 and I found that there it has  something called 'the analog switch'.

The TSC is composed of several groups. Each group is composed of 4 I/Os being one of them dedicated for one  reference capacitor (Cs) while the other 3 are dedicated for connecting capacitive buttons. What I suspect is that one analog switch belong to one group, and it can be used to connect internally the I/Os of a group.

Does anyone have experience with this topic? any code example? Mi goal is to connect internally and programatically two I/Os for certain time and after separate them.

Thank you all. Any help is highly appreciated.

Best regards,

Diego Ballen

#stm32-l0 #analog-switch #tsc

[Imen.D]

Posted on November 20, 2017 at 11:40

Hello

diego_ballen

,

I recommended you to start from the TouchSensing application under the STM32CubeL0 firmware package:

STM32Cube_FW_L0_V1.0\Projects\STM32L053C8-Discovery\Applications\TouchSensing

You may find clarification and more details on how to use the TSC referring to the UM1913: 'Developing applications on STM32Cube with touch sensing' and

http://www.st.com/content/ccc/resource/training/technical/product_training/6b/ea/47/06/18/83/43/67/STM32L4_Peripheral_Touchsense.pdf/files/STM32L4_Peripheral_Touchsense.pdf/jcr:content/translations/en.STM32L4_Peripheral_Touchsense.pdf

Hope this bring you some help.

Best Regards

Imen

[Diego Ballen]

Posted on November 20, 2017 at 18:12

Hello Imen D,

thank you very much for your answer. I was checking the example, but I could not found any part of the code in which some kind of internal switch was activated to join two I/Os and charge the Cs with the Cx. Basically what is done here is to initialize the TSC, start the acquisition by writing a register and then wait until Cs achieves certain voltage. When this happens the conversion is finished.

I could not find any code to control the analog switch to temporaly join two I/Os.

Thank you again for your help.

Best regards,

Diego Ballen

[waclawek.jan · Accepted solution]

Posted on November 20, 2017 at 18:26

I agree that RM could be clearer in this respect, but do you expect it to be anything more than a single write to the analog switch register (TSC_IOASCR)?

JW

[Diego Ballen]

Posted on November 21, 2017 at 10:59

Hello Wacklawek.jan,

thank you very much for your suggestion. I just activate the analog switch for the two pins I wanted to join by writing the TSC_IOASCR register and that made the trick.

Again thanks for your help!

Diego Ballen