FDC2114EVM: Issue with proximity detection

Isaac Parsons

Part Number: FDC2114EVM
Other Parts Discussed in Thread: FDC2114, FDC2214, LDC2114, , FDC2214EVM

I recently received the FDC2114 Evaluation module and after testing it we are only getting significant changes in the capacitance when the plate is directly touched. For our application we would like to be able to have a bigger change in the capacitance when an object comes within approximately 2cm to 4cm range of the sensor (but not directly touching), after playing with the evaluation board we are only getting about a change in the capacitance of about 0.4pF. What should we do in order to increase the resolution of the changes in the capacitance in the 2cm to 4cm range?

over 7 years ago

0 Kristin Jones93 over 7 years ago

TI__Genius 17440 points

Hi Isaac,

The sensitivity of the system is proportional to the size of the sensor. I would recommend breaking off the default sensors and replacing them with a large copper plate. You may find this application note about proximity sensing with the FDC2x1y devices helpful.

Regards,

0 Isaac Parsons over 7 years ago in reply to Kristin Jones93

Intellectual 450 points

Is there anything that can be done if the sensor plate is a fixed size that cannot be changed?

0 Kristin Jones93 over 7 years ago in reply to Isaac Parsons

TI__Genius 17440 points

The only other option is to minimize the sample rate (by maximizing RCOUNT), but this will have a significantly smaller effect than changing the sensor size.

0 Isaac Parsons over 7 years ago in reply to Kristin Jones93

Intellectual 450 points

Ok, thank you for the help, I appreciate it. I was looking at the datasheet and if I know that the change in the capacitance will be small will changing the bias and increasing the gain allow for a higher resolution of capacitance values?

0 Kristin Jones93 over 7 years ago in reply to Isaac Parsons

TI__Genius 17440 points

Hi Isaac,

Using the gain will improve the resolution, but not the overall magnitude of the shift in capacitance. If the 0.4pF shift in capacitance is enough for your application with the additional resolution from the gain, then this would also be an option. You can also use the FDC2214, which has 28 bits of resolution and is pin-to-pin compatible with the FDC2114.

Regards,

0 Isaac Parsons over 7 years ago in reply to Kristin Jones93

Intellectual 450 points

Ok, Thank you very much for taking the time to reply, this was very helpful

0 Isaac Parsons over 7 years ago in reply to Kristin Jones93

Intellectual 450 points

Sorry, just to confirm did you mean the FDC2214 is compatible with the FDC2114 (instead of the LDC2214 is compatible with the LDC2114)

0 Kristin Jones93 over 7 years ago in reply to Isaac Parsons

TI__Genius 17440 points

My apologies, I did mean the FDC2214 is pin-to-pin compatible with the FDC2114. I will edit my previous reply so this is clear.

Regards,

0 Isaac Parsons over 6 years ago in reply to Kristin Jones93

Intellectual 450 points

Sorry, just wanted to double check before I break something. So I can just desolder the FDC2114 from the FDC2114 evaluation board and solder on the FDC2214 and it will work?

0 Kristin Jones93 over 6 years ago in reply to Isaac Parsons

TI__Genius 17440 points

Hi Isaac,

Yes, you can replace the FDC2114 on the FDC2114EVM with an FDC2214 and the board will still work. The devices are pin to pin compatible and the EVMs are identical except for the FDC device.

Note that you may need to reprogram the firmware on the EVM so that the firmware correctly recognizes the board as an FDC2214EVM. You can do this by opening the GUI and selecting the firmware tab, then selecting the "FDC2x14_LDC13xxRevB_LDC16xxRevB_EVM_Firmware.txt" file located in C:\ti\Sensing Solutions EVM GUI-1.9.4\EVM Firmware

Regards,

0 Isaac Parsons over 6 years ago in reply to Kristin Jones93

Intellectual 450 points

Thanks!

0 Isaac Parsons over 6 years ago in reply to Kristin Jones93

Intellectual 450 points

Hi, i replaced the fdc2114 with the fdc2214. I have double checked and it is in fact the FDC2214, I tried reinstalling the firmware on the GUI, but no matter what I do the gui says that its the fdc2114? Is there somewhere I can directly download the fdc2214 firmware?

thanks