• State
  • Locked Locked
  • Replies 7 replies
  • Subscribers 34 subscribers
  • Views 658 views
  • Users 0 members are here
Support feedback
Options
Options
Related

This thread has been locked.

If you have a related question, please click the "Ask a related question" button in the top right corner. The newly created question will be automatically linked to this question.

TCA8424 / ANY KEYBOARD INTERFACE

Ran Feldman
Intellectual 780 points
Other Parts Discussed in Thread: TCA8424

Hi,

Does the TCA8424 can be interfaced to any keyboard? meaning be used for example with a 8*8 keyboard that is not running under Win8 and not using the HID feature?

From the Data Sheet it looks like it does, the controller will issue an interrupt and a low cost MCU can read the I2C data.

What should be done with Row*Col that are not used? (I understand that the pins will be automatically pulled down/up on start up, is that enough, can they be left "floating"?

Thanks,

Rani  

  • 0
    TI__Expert 6395 points

    Hello Rani,

    Yes the TCA8424 can be interfaced with any keyboard.  You will have to write firmware for the MCU to read and interpret the I2C data.

    Unused row pins can be left floating. (You will be using all 8 column pins)

    If you plan on ignoring the HID spec completely here are some pointers:

    • Ignore both the HID descriptor and Report Descriptor both in the OTP and in the MCU (It is not necessary for these registers to be read on startup)
    • You must read the input report on startup. After this the device will operate normally. (It will be all 0's per the HID spec on the initial read)
    • If you plan on using special function keys such as volume up and down I would suggest implementing these as regular keys in the keyboard map as it will simplify your firmware (vs trying to use the HID multiple report ID method)
    • Some example firmware is available for implementing the HID commands for sleep mode and using the LED drivers on theTCA8424 product page
    • An OTP creation guide and template(you must click the read abstract to see this template) is also available on the product page

    Let me know if you have any questions.

    Regards,

    Andrew

  • 0 in reply to Andrew_Mason
    Prodigy 30 points

    Hello Andrew,
    I understand that TC8424 has pre-programmed keyboard map. Where can i find the detailed information on these map?
    We are going to design a 104-key keyboard using TCA8424.


    Thanks.

    Best regards,

    Ren

  • 0 in reply to Ren Li
    TI__Expert 6395 points

    Hello Ren,

    By default the keyboard map is un-programmed and you can use the EVM with the software provided to program it yourself if desired.

    Regards,

    Andrew

  • 0 in reply to Andrew_Mason
    Prodigy 30 points

    Hi Andrew,

    Thanks for your advice.

    What about for production? We do not want to programme each chip during production.

    Does TI supplied chips with preprogrammed standard keyboard map for production

    purchase?

    Thanks again for your help to advice as I understand my question may be more logistics related.

    Best,

    Ren

  • 0 in reply to Ren Li
    TI__Expert 6395 points

    Hello Ren,

    Do you know your expected volumes for the project?  If you do not feel comfortable providing the information on the forums I can post my email address for you to send directly to me.

    Regards,

    Andrew

  • 0 in reply to Andrew_Mason
    Prodigy 30 points

    Dear Andrew,

    Thanks. Please post your email address to write to you directly.

    Alternatively, you could send your email address to my email address registered in my TI account.

    Thanks/regards,

    Ren

  • 0 in reply to Ren Li
    TI__Expert 6395 points

    Hello Ren,

    Please contact me at a-mason@ti.com.

    Regards,

    Andrew