I/Os available for Capacitive Sensing in PROC-UI – KBA82019

Version: *A


Question: How many I/Os are free for capacitive sensing in PRoC-UI?



The PRoC-TT (68 pin) part has 35 general purpose I/Os (GPIOs) for capacitive sensing while the PRoC-CS (40 pin) has 13 GPIOs for capacitive sensing. The I/Os required for radio control and external modulator capacitor and the I/Os available for capacitive sensing are outlined below:

     Part     Total GPIOs     I/Os Required for Radio Control     I/Os Required for External Modulator Capacitor (Cmod)     I/Os Available for Capacitive Sensing
     35     4 for SPI 1 for radio reset     1     26
     13     4 for SPI and 1 for radio reset     1     7
     35     4 for SPI and 1 for radio reset     1     26

Thus in the case of PRoC-CS (40 pin) you have 7 general purpose I/Os free for capacitive buttons in your design if you want to use the radio. The 7 I/Os can be used to support a maximum of 12 buttons using a matrix layout or it can be used to support a maximum of 14 segments on a capacitive slider using a diplexer. The 68 pin PRoC-CS part has 35 GPIOs (26 for capacitive sensing) and can be used for applications where there is a need for larger number of GPIOs.

The PRoC-TT part supports 35 general purpose I/Os that can be used for capacitive sensing. If you are using the radio, a maximum of 26 XY sensors are available for touch support.