Getting FPC1020a to communicate

Hi all,

I'm working on communicating with the fpc1020a module. I am using the libraries found on this arduino post, which provides the libraries and programming instructions. The unit I am using is from amazon found here. The modules look almost identical, and both are using the same ARM MCU (GD32F105).

Upon following the instructions I see no response from 3 separate devices, whether I have tried talking to it over UART or hooked it up to a scope and touched it while watching for signals on any of its pins. The device in the instructions is slightly different, but I confirmed the pinout is the same by tracing the pins back the the MCU. The only difference I can confirm is the MCU claims to be operated at 3.3V (based on the Datasheet and Manual) rather than the instruction's claim of 5V. After using 5V on one chip I realized it got incredibly hot to the touch, but it feels normal when using 3.3V so that is what I am using. I decided not to use this chip anymore.

Hooking the TX pin of the FPC1020a up to a scope I see it go high (3.3V) for UART, but no matter what I send to the FPC1020a's RX line, I get no response.

Has anyone actually used this device before? Any help is appreciated, I am very lost. I am wondering if there is some kind of initialization that needs to be done before it will start to respond.

My setup:

ESP32 TX -> FPC1020a RX
ESP32 RX -> FPC1020a TX
ESP32 Vin -> 3.3V
ESP32 GND -> GND
FPC1020a Vin -> 3.3V
FPC1020a GND -> GND

I did not wire up the FPC1020a's V-TOUCH or TOUCH pins, since it says it is not needed on the instructions, however the instructions also list the V-TOUCH pin as POWER in the I/O section, which is a bit confusing.

TIA

Hi, I have the same device. Did you had any luck communicating and getting it to work?

Also I cannot find lot of support materials for the FPC1020A version....

Just made a discovery. You could simply use the given 1020 sample in Arduino forum. However Rx and Tx swapped on the 1020A model. Please wire based on the following diagram. All works well..

Hi.. do you have any working sketch? I am trying to compile INO from your ZIP but everytime I am ending with error:

FPC1020.cpp:6:0:
FPC1020.h:45:28: error: expected ')' before '*' token
FPC1020(SoftwareSerial *ser);
^

I'm working on a library for the module and I should have it up on Github soon. After all, its a good time to stay inside.

I could use some help with something else. On day 1, I applied 5v to the module Vcc, and the board got quite toasty. I'm running it on 3v3 now and it's fine. However, I cannot seem to get IRQ to work. It could be that my 5v ruined something on my board and I don't have another to verify.

As far as I understand from the Chinese documentation, it basically behaves like a capacitive button, like a TTP223 (it is a TTP223). However, probing the Vdd pin on the chip shows it's effectively at ground potential. I have traced it to an NPN transistor (Y1) closest to the connector GND pin, and that transistor is being driven by the identical one next to it, which is driven by the uC. The output of the uC is always high and I can't figure out how to turn it off. It is keeping the Vdd low by turning on both transistors and bringing Vdd to ground potential.

I could be wrong, but I'm thinking that it's wired wrongly on the PCB and that Vdd should have been on the Emitter side. Shorting out the first stage transistor (connected to uC), effectively turning of the second transistor, gives 3v3 at the Vdd but still no luck with the IRQ output.

Secondly, I traced the input detection pin to the IC and found that it is connected to the metal part of the sensor, with a capacitor in between. The application note given in the datasheet for the TP223 does not include this cap and could be a source of why it's not working as well.

I can only speculate as I don't have other modules to test on and I might have toasted mine with 5v. In the meantime, I'm working on the library as all of the documentation is in Mandarine.