• TI Thinks Resolved

DLP4710EVM-LC: LC commands not working via onboard I2C (J11)

Prodigy 50 points

Replies: 4

Views: 65

Part Number: DLP4710EVM-LC


I'm trying to communicate through onboard i2c header J11, not via USB/Cypress, with the DLP4710EVM-LC.

But cannot read or write any Light Control commands (90h-9Fh).

Other commands working without any problem, both reading/writing.

Is possible using LC command via this i2C? Is needed any master/slave switching via GPIO or some commands before sending LC cmd?

Thank You


Honza Holub


  • DLP4710EVM-LC
  • EVM SW 4.2.2
  • EVM FW 7.0.1

  • Hello Honza,

    Have you disabled the MSP430 on the EVM to avoid I2C bus conflicts? Please see this guide: EVM I2C Access.pdf



  • In reply to Kyle Rakos:

    Hello Kylle

    No, I no disabling MSP430.

    If i good understand that, In schematics of  DLP4710EVM, J11 connector is connected only to "slave" i2c - "Ext I2C" on page 9. This I2C line is connected only to MSP430, and not to DLPC3479 controller. All resistors, thats interconnect IC0_SCL/SDA and MSP430_S_SCL/SDA not fitted ("DNI" on schema).

    Is necessary add this resistors and disable MSP430 via GPIO5 and GPIO9?

    I don't understand it...

    Thank You very much for Your answer
    Honza H
  • In reply to Jan Holub:

    Hello Honza,

    Please see the guide above to perform the proper MSP430 handshake or to find another way to ensure there are no I2C bus conflicts. A standard way to ensure this would be to use the Cypress driver as mentioned in the guide.

    If you need direct I2C access you still need to ensure there are no MSP430 bus conflicts. Also note for I2C line access you can also use TP249 and TP248. If you want to use J11 you will likely need to solder the uninstalled resistors (such as R177  and R178). Please see the schematic for full details. 



  • In reply to Kyle Rakos:

    Ok, Thank You Kyle for clarifying. I will do some hw/sw changes, or use i2c via Cypress.

    Thank You


    Honza H