Linux/TCA8418: Mutliple Keys press events are received.

Part Number: TCA8418

Tool/software: Linux

hi,

I have a keypad matrix 4 rows and 3 cols and 6 function keys as single input (only the 4x3 keys work, the F1-F6 are not working

I have successfully connected our custom board to our custom PCB. I can see the dmesg and it linked to event0

I can run evtest successfully but when I press some buttons (4x3 keys), I see keys events I don't expect. I attached the evtest below. Is there an error in my hardware board schematic? Am I missing something?

keys 1, 4, 7, * all work great

keys 2, 5, 8, 0 show an extra key (previous column)

keys 3, 6, 9, enter show two extra keys (previous 2 columns) for each press

I will attach my keypad schematic. what I am looking for from this forum is to determine if my hardware schematic is correct for the TCA8418 or is there an error (missing pull up resistor or likes). I also don't like the way the designer direct connected F1-F6 and may we just make a 3x6 matrix for all items.

thanks,

Zev.

evtest output

-----------------

root@var-som-mx6:~# evtest
No device specified, trying to scan all of /dev/input/event*
Available devices:
/dev/input/event0:      tca8418
/dev/input/event1:      Logitech USB Optical Mouse
/dev/input/event2:      gpio-keys
Select the device event number [0-2]: 0
Input driver version is 1.0.1
Input device ID: bus 0x18 vendor 0x1 product 0x1 version 0x1
Input device name: "tca8418"
Supported events:
Event type 0 (EV_SYN)
Event type 1 (EV_KEY)
    Event code 28 (KEY_ENTER)
    Event code 59 (KEY_F1)
    Event code 60 (KEY_F2)
    Event code 61 (KEY_F3)
    Event code 62 (KEY_F4)
    Event code 63 (KEY_F5)
    Event code 64 (KEY_F6)
    Event code 512 (KEY_NUMERIC_0)
    Event code 513 (KEY_NUMERIC_1)
    Event code 514 (KEY_NUMERIC_2)
    Event code 515 (KEY_NUMERIC_3)
    Event code 516 (KEY_NUMERIC_4)
    Event code 517 (KEY_NUMERIC_5)
    Event code 518 (KEY_NUMERIC_6)
    Event code 519 (KEY_NUMERIC_7)
    Event code 520 (KEY_NUMERIC_8)
    Event code 521 (KEY_NUMERIC_9)
    Event code 522 (KEY_NUMERIC_STAR)
Event type 4 (EV_MSC)
    Event code 4 (MSC_SCAN)
Properties:
Testing ... (interrupt to exit)

pressing number 1
Event: time 1545109317.211748, type 4 (EV_MSC), code 4 (MSC_SCAN), value 02
Event: time 1545109317.211748, type 1 (EV_KEY), code 513 (KEY_NUMERIC_1), value 1
Event: time 1545109317.211748, type 4 (EV_MSC), code 4 (MSC_SCAN), value 03
Event: time 1545109317.211748, type 4 (EV_MSC), code 4 (MSC_SCAN), value 04
Event: time 1545109317.211748, -------------- SYN_REPORT ------------
Event: time 1545109317.397339, type 4 (EV_MSC), code 4 (MSC_SCAN), value 02
Event: time 1545109317.397339, type 1 (EV_KEY), code 513 (KEY_NUMERIC_1), value 0
Event: time 1545109317.397339, type 4 (EV_MSC), code 4 (MSC_SCAN), value 03
Event: time 1545109317.397339, type 4 (EV_MSC), code 4 (MSC_SCAN), value 04
Event: time 1545109317.397339, -------------- SYN_REPORT ------------

pressing number 2
Event: time 1545109328.440710, type 4 (EV_MSC), code 4 (MSC_SCAN), value 01
Event: time 1545109328.440710, type 1 (EV_KEY), code 514 (KEY_NUMERIC_2), value 1
Event: time 1545109328.440710, type 4 (EV_MSC), code 4 (MSC_SCAN), value 02
Event: time 1545109328.440710, type 1 (EV_KEY), code 513 (KEY_NUMERIC_1), value 1
Event: time 1545109328.440710, type 4 (EV_MSC), code 4 (MSC_SCAN), value 03
Event: time 1545109328.440710, -------------- SYN_REPORT ------------
Event: time 1545109328.579526, type 4 (EV_MSC), code 4 (MSC_SCAN), value 01
Event: time 1545109328.579526, type 1 (EV_KEY), code 514 (KEY_NUMERIC_2), value 0
Event: time 1545109328.579526, type 4 (EV_MSC), code 4 (MSC_SCAN), value 02
Event: time 1545109328.579526, type 1 (EV_KEY), code 513 (KEY_NUMERIC_1), value 0
Event: time 1545109328.579526, type 4 (EV_MSC), code 4 (MSC_SCAN), value 03
Event: time 1545109328.579526, -------------- SYN_REPORT ------------

pressing number 3
Event: time 1545109337.702155, type 4 (EV_MSC), code 4 (MSC_SCAN), value 00
Event: time 1545109337.702155, type 1 (EV_KEY), code 515 (KEY_NUMERIC_3), value 1
Event: time 1545109337.702155, type 4 (EV_MSC), code 4 (MSC_SCAN), value 01
Event: time 1545109337.702155, type 1 (EV_KEY), code 514 (KEY_NUMERIC_2), value 1
Event: time 1545109337.702155, type 4 (EV_MSC), code 4 (MSC_SCAN), value 02
Event: time 1545109337.702155, type 1 (EV_KEY), code 513 (KEY_NUMERIC_1), value 1
Event: time 1545109337.702155, -------------- SYN_REPORT ------------
Event: time 1545109337.887568, type 4 (EV_MSC), code 4 (MSC_SCAN), value 00
Event: time 1545109337.887568, type 1 (EV_KEY), code 515 (KEY_NUMERIC_3), value 0
Event: time 1545109337.887568, type 4 (EV_MSC), code 4 (MSC_SCAN), value 01
Event: time 1545109337.887568, type 1 (EV_KEY), code 514 (KEY_NUMERIC_2), value 0
Event: time 1545109337.887568, type 4 (EV_MSC), code 4 (MSC_SCAN), value 02
Event: time 1545109337.887568, type 1 (EV_KEY), code 513 (KEY_NUMERIC_1), value 0
Event: time 1545109337.887568, -------------- SYN_REPORT ------------

pressing number 4
Event: time 1545109348.313482, type 4 (EV_MSC), code 4 (MSC_SCAN), value 12
Event: time 1545109348.313482, type 1 (EV_KEY), code 516 (KEY_NUMERIC_4), value 1
Event: time 1545109348.313482, type 4 (EV_MSC), code 4 (MSC_SCAN), value 13
Event: time 1545109348.313482, type 4 (EV_MSC), code 4 (MSC_SCAN), value 14
Event: time 1545109348.313482, -------------- SYN_REPORT ------------
Event: time 1545109348.475754, type 4 (EV_MSC), code 4 (MSC_SCAN), value 12
Event: time 1545109348.475754, type 1 (EV_KEY), code 516 (KEY_NUMERIC_4), value 0
Event: time 1545109348.475754, type 4 (EV_MSC), code 4 (MSC_SCAN), value 13
Event: time 1545109348.475754, type 4 (EV_MSC), code 4 (MSC_SCAN), value 14
Event: time 1545109348.475754, -------------- SYN_REPORT ------------

pressing number 5
Event: time 1545109359.762071, type 4 (EV_MSC), code 4 (MSC_SCAN), value 11
Event: time 1545109359.762071, type 1 (EV_KEY), code 517 (KEY_NUMERIC_5), value 1
Event: time 1545109359.762071, type 4 (EV_MSC), code 4 (MSC_SCAN), value 12
Event: time 1545109359.762071, type 1 (EV_KEY), code 516 (KEY_NUMERIC_4), value 1
Event: time 1545109359.762071, type 4 (EV_MSC), code 4 (MSC_SCAN), value 13
Event: time 1545109359.762071, -------------- SYN_REPORT ------------
Event: time 1545109359.901037, type 4 (EV_MSC), code 4 (MSC_SCAN), value 11
Event: time 1545109359.901037, type 1 (EV_KEY), code 517 (KEY_NUMERIC_5), value 0
Event: time 1545109359.901037, type 4 (EV_MSC), code 4 (MSC_SCAN), value 12
Event: time 1545109359.901037, type 1 (EV_KEY), code 516 (KEY_NUMERIC_4), value 0
Event: time 1545109359.901037, type 4 (EV_MSC), code 4 (MSC_SCAN), value 13
Event: time 1545109359.901037, -------------- SYN_REPORT ------------

pressing number 6
Event: time 1545109370.390124, type 4 (EV_MSC), code 4 (MSC_SCAN), value 10
Event: time 1545109370.390124, type 1 (EV_KEY), code 518 (KEY_NUMERIC_6), value 1
Event: time 1545109370.390124, type 4 (EV_MSC), code 4 (MSC_SCAN), value 11
Event: time 1545109370.390124, type 1 (EV_KEY), code 517 (KEY_NUMERIC_5), value 1
Event: time 1545109370.390124, type 4 (EV_MSC), code 4 (MSC_SCAN), value 12
Event: time 1545109370.390124, type 1 (EV_KEY), code 516 (KEY_NUMERIC_4), value 1
Event: time 1545109370.390124, -------------- SYN_REPORT ------------
Event: time 1545109370.575728, type 4 (EV_MSC), code 4 (MSC_SCAN), value 10
Event: time 1545109370.575728, type 1 (EV_KEY), code 518 (KEY_NUMERIC_6), value 0
Event: time 1545109370.575728, type 4 (EV_MSC), code 4 (MSC_SCAN), value 11
Event: time 1545109370.575728, type 1 (EV_KEY), code 517 (KEY_NUMERIC_5), value 0
Event: time 1545109370.575728, type 4 (EV_MSC), code 4 (MSC_SCAN), value 12
Event: time 1545109370.575728, type 1 (EV_KEY), code 516 (KEY_NUMERIC_4), value 0
Event: time 1545109370.575728, -------------- SYN_REPORT ------------

pressing number 7
Event: time 1545109379.717056, type 4 (EV_MSC), code 4 (MSC_SCAN), value 22
Event: time 1545109379.717056, type 1 (EV_KEY), code 519 (KEY_NUMERIC_7), value 1
Event: time 1545109379.717056, type 4 (EV_MSC), code 4 (MSC_SCAN), value 23
Event: time 1545109379.717056, type 4 (EV_MSC), code 4 (MSC_SCAN), value 24
Event: time 1545109379.717056, -------------- SYN_REPORT ------------
Event: time 1545109379.925596, type 4 (EV_MSC), code 4 (MSC_SCAN), value 22
Event: time 1545109379.925596, type 1 (EV_KEY), code 519 (KEY_NUMERIC_7), value 0
Event: time 1545109379.925596, type 4 (EV_MSC), code 4 (MSC_SCAN), value 23
Event: time 1545109379.925596, type 4 (EV_MSC), code 4 (MSC_SCAN), value 24
Event: time 1545109379.925596, -------------- SYN_REPORT ------------

prssing number 8
Event: time 1545109387.805598, type 4 (EV_MSC), code 4 (MSC_SCAN), value 21
Event: time 1545109387.805598, type 1 (EV_KEY), code 520 (KEY_NUMERIC_8), value 1
Event: time 1545109387.805598, type 4 (EV_MSC), code 4 (MSC_SCAN), value 22
Event: time 1545109387.805598, type 1 (EV_KEY), code 519 (KEY_NUMERIC_7), value 1
Event: time 1545109387.805598, type 4 (EV_MSC), code 4 (MSC_SCAN), value 23
Event: time 1545109387.805598, -------------- SYN_REPORT ------------
Event: time 1545109387.990950, type 4 (EV_MSC), code 4 (MSC_SCAN), value 21
Event: time 1545109387.990950, type 1 (EV_KEY), code 520 (KEY_NUMERIC_8), value 0
Event: time 1545109387.990950, type 4 (EV_MSC), code 4 (MSC_SCAN), value 22
Event: time 1545109387.990950, type 1 (EV_KEY), code 519 (KEY_NUMERIC_7), value 0
Event: time 1545109387.990950, type 4 (EV_MSC), code 4 (MSC_SCAN), value 23
Event: time 1545109387.990950, -------------- SYN_REPORT ------------

pressing number 9
Event: time 1545109396.270974, type 4 (EV_MSC), code 4 (MSC_SCAN), value 20
Event: time 1545109396.270974, type 1 (EV_KEY), code 521 (KEY_NUMERIC_9), value 1
Event: time 1545109396.270974, type 4 (EV_MSC), code 4 (MSC_SCAN), value 21
Event: time 1545109396.270974, type 1 (EV_KEY), code 520 (KEY_NUMERIC_8), value 1
Event: time 1545109396.270974, type 4 (EV_MSC), code 4 (MSC_SCAN), value 22
Event: time 1545109396.270974, type 1 (EV_KEY), code 519 (KEY_NUMERIC_7), value 1
Event: time 1545109396.270974, -------------- SYN_REPORT ------------
Event: time 1545109396.456231, type 4 (EV_MSC), code 4 (MSC_SCAN), value 20
Event: time 1545109396.456231, type 1 (EV_KEY), code 521 (KEY_NUMERIC_9), value 0
Event: time 1545109396.456231, type 4 (EV_MSC), code 4 (MSC_SCAN), value 21
Event: time 1545109396.456231, type 1 (EV_KEY), code 520 (KEY_NUMERIC_8), value 0
Event: time 1545109396.456231, type 4 (EV_MSC), code 4 (MSC_SCAN), value 22
Event: time 1545109396.456231, type 1 (EV_KEY), code 519 (KEY_NUMERIC_7), value 0
Event: time 1545109396.456231, -------------- SYN_REPORT ------------

pressing asterisk
Event: time 1545109408.351310, type 4 (EV_MSC), code 4 (MSC_SCAN), value 32
Event: time 1545109408.351310, type 1 (EV_KEY), code 522 (KEY_NUMERIC_STAR), value 1
Event: time 1545109408.351310, type 4 (EV_MSC), code 4 (MSC_SCAN), value 33
Event: time 1545109408.351310, type 4 (EV_MSC), code 4 (MSC_SCAN), value 34
Event: time 1545109408.351310, -------------- SYN_REPORT ------------
Event: time 1545109408.559884, type 4 (EV_MSC), code 4 (MSC_SCAN), value 32
Event: time 1545109408.559884, type 1 (EV_KEY), code 522 (KEY_NUMERIC_STAR), value 0
Event: time 1545109408.559884, type 4 (EV_MSC), code 4 (MSC_SCAN), value 33
Event: time 1545109408.559884, type 4 (EV_MSC), code 4 (MSC_SCAN), value 34
Event: time 1545109408.559884, -------------- SYN_REPORT ------------

pressing 0
Event: time 1545109417.783275, type 4 (EV_MSC), code 4 (MSC_SCAN), value 31
Event: time 1545109417.783275, type 1 (EV_KEY), code 512 (KEY_NUMERIC_0), value 1
Event: time 1545109417.783275, type 4 (EV_MSC), code 4 (MSC_SCAN), value 32
Event: time 1545109417.783275, type 1 (EV_KEY), code 522 (KEY_NUMERIC_STAR), value 1
Event: time 1545109417.783275, type 4 (EV_MSC), code 4 (MSC_SCAN), value 33
Event: time 1545109417.783275, -------------- SYN_REPORT ------------
Event: time 1545109417.968590, type 4 (EV_MSC), code 4 (MSC_SCAN), value 31
Event: time 1545109417.968590, type 1 (EV_KEY), code 512 (KEY_NUMERIC_0), value 0
Event: time 1545109417.968590, type 4 (EV_MSC), code 4 (MSC_SCAN), value 32
Event: time 1545109417.968590, type 1 (EV_KEY), code 522 (KEY_NUMERIC_STAR), value 0
Event: time 1545109417.968590, type 4 (EV_MSC), code 4 (MSC_SCAN), value 33
Event: time 1545109417.968590, -------------- SYN_REPORT ------------

pressing enter
Event: time 1545109429.240499, type 4 (EV_MSC), code 4 (MSC_SCAN), value 30
Event: time 1545109429.240499, type 1 (EV_KEY), code 28 (KEY_ENTER), value 1
Event: time 1545109429.240499, type 4 (EV_MSC), code 4 (MSC_SCAN), value 31
Event: time 1545109429.240499, type 1 (EV_KEY), code 512 (KEY_NUMERIC_0), value 1
Event: time 1545109429.240499, type 4 (EV_MSC), code 4 (MSC_SCAN), value 32
Event: time 1545109429.240499, type 1 (EV_KEY), code 522 (KEY_NUMERIC_STAR), value 1
Event: time 1545109429.240499, -------------- SYN_REPORT ------------
Event: time 1545109429.402877, type 4 (EV_MSC), code 4 (MSC_SCAN), value 30
Event: time 1545109429.402877, type 1 (EV_KEY), code 28 (KEY_ENTER), value 0
Event: time 1545109429.402877, type 4 (EV_MSC), code 4 (MSC_SCAN), value 31
Event: time 1545109429.402877, type 1 (EV_KEY), code 512 (KEY_NUMERIC_0), value 0
Event: time 1545109429.402877, type 4 (EV_MSC), code 4 (MSC_SCAN), value 32
Event: time 1545109429.402877, type 1 (EV_KEY), code 522 (KEY_NUMERIC_STAR), value 0
Event: time 1545109429.402877, -------------- SYN_REPORT ------------

pressing F1
thru F6 do nothing

^Croot@var-som-mx6:~#

my device tree mapping on i2c

-------------------

keypad: tca8418@34 {
        compatible = "ti,tca8418";
        reg = <0x34>;
        row-output-enabled;
        col-debounce-filter-period = <5>;
        pull-up-enabled;
        debounce-delay-ms = <4>;
         interrupt-parent = <&gpio5>;
         interrupts = <13 IRQ_TYPE_EDGE_FALLING>;
         keypad,num-columns = <10>;Schematic_KEYPAD.pdf keypad,num-rows = <8>;
         linux,no-autorepeat;

linux,keymap = <
       MATRIX_KEY(0x00, 0x02, KEY_NUMERIC_1) /*ROW0, COLUMN2*/
       MATRIX_KEY(0x00, 0x01, KEY_NUMERIC_2) /*ROW0, COLUMN1*/
                     MATRIX_KEY(0x00, 0x00, KEY_NUMERIC_3) /*ROW0, COLUMN0*/

                     MATRIX_KEY(0x01, 0x02, KEY_NUMERIC_4) /*ROW1, COLUMN2*/
                     MATRIX_KEY(0x01, 0x01, KEY_NUMERIC_5) /*ROW1, COLUMN1*/
                     MATRIX_KEY(0x01, 0x00, KEY_NUMERIC_6) /*ROW1, COLUMN0*/

                     MATRIX_KEY(0x02, 0x02, KEY_NUMERIC_7) /*ROW2, COLUMN2*/
                     MATRIX_KEY(0x02, 0x01, KEY_NUMERIC_8) /*ROW2, COLUMN1*/
                     MATRIX_KEY(0x02, 0x00, KEY_NUMERIC_9) /*ROW2, COLUMN0*/

                     MATRIX_KEY(0x03, 0x02, KEY_NUMERIC_STAR) /*ROW3, COLUMN2*/
                     MATRIX_KEY(0x03, 0x01, KEY_NUMERIC_0) /*ROW3, COLUMN1*/
                     MATRIX_KEY(0x03, 0x00, KEY_ENTER)       /*ROW3, COLUMN0*/

                     MATRIX_KEY(0x07, 0x04, KEY_F1) /*ROW4, COLUMN4*/
                     MATRIX_KEY(0x07, 0x05, KEY_F2) /*ROW4, COLUMN5*/
                     MATRIX_KEY(0x07, 0x06, KEY_F3) /*ROW4, COLUMN6*/
                     MATRIX_KEY(0x07, 0x07, KEY_F4) /*ROW4, COLUMN7*/
       MATRIX_KEY(0x07, 0x08, KEY_F5) /*ROW4, COLUMN8*/
        MATRIX_KEY(0x07, 0x09, KEY_F6) /*ROW4, COLUMN9*/
        >;

};

over 5 years ago

0 ZB over 5 years ago

Prodigy 135 points

Could not seem to upload the PDF of the schematic so i pasted the link from dropbox

Keyboard Schematic:

https://www.dropbox.com/s/jg1z76kipx5pxgz/Schematic_KEYPAD.pdf?dl=0

thanks!

Zev

0 Max Robertson over 5 years ago in reply to ZB

TI__Guru 62910 points

Hi Zev,

Due to some restrictions on filesharing sites at our company I can't access the dropbox link you provided. However, I can tell you that the most likely cause of seeing multiple key presses corresponding to adjacent columns is that the signals take too long to transition back to a high level due to the presence of parasitic capacitance. The ROW inputs of this device are only weakly pulled up internally, and so adding external pull-up resistances (~10 kOhms, for example) typically helps speed up the low-to-high transition. If you don't have these pull-ups in your current implementation, I would recommend first adding them and seeing if this clear up the problem. (If not, let me know and let's brainstorm further.)

Regards,
Max

0 ZB over 5 years ago in reply to Max Robertson

Prodigy 135 points

the schematic. added as an image :)

0 Max Robertson over 5 years ago in reply to ZB

TI__Guru 62910 points

That worked - thanks! I see you already have some pull-up resistances, but is it possible to remove (or reduce) the capacitances C1, C2, and C3? These may be slowing down the signals enough that the voltage is still considered "low" when scanning the adjacent column.

Regards,
Max

0 ZB over 5 years ago in reply to Max Robertson

Prodigy 135 points

Ok. Give me a day. I can't reduce but I can remove C1, C2 and C3.
Everything else look ok?

0 Max Robertson over 5 years ago in reply to ZB

TI__Guru 62910 points

Yes, the rest of the schematic looks OK to me.

Regards,
Max

0 ZB over 5 years ago in reply to Max Robertson

Prodigy 135 points

Max,
Thank you for your help. i removed C1, C2 and C3 (left them open) and then it all started to work perfectly.
Zev.

0 Max Robertson over 5 years ago in reply to ZB

TI__Guru 62910 points

Zev,

Glad to hear it! Thanks for the update. Note that this device does implement a "debounce" filter internally, so it should be fine to operate without these capacitors on your PCB.

Max

Interface

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Linux/TCA8418: Mutliple Keys press events are received.