Sending TWI commands/data without the preceding device address?

Hello, I am trying to communicate with a Newhaven LCD display using the ADSP-21469 EZ-KIT and the TWI interface in Master mode.  I have set everything up and am able to send commands and data to the display and I am able to see the acknowledgement bit assert using an oscilloscope.  However, the device is not displaying anything after duplicating the manufacturer's initialization procedure.  One thing I've noticed is that the TWI controller always sends the slave address prior to each byte of data, and I am wondering if this is the problem.  Is it possible to simply send a byte of data without the preceding slave address when using the TWI interface?  Thank you in advance for your help!

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  • +1
    •  Analog Employees 
    on Apr 4, 2019 6:53 AM

    Hi Jeff,

    As mentioned in the HRM under "Master Mode Addressing" section, whether enabled as a master-transmitter or master-receiver with 7-bit addressing using the TWIMLENbit, the TWI master performs all addressing and data transfers as required. This includes generating the repeated start condition, re-transmission of the 7-bits of the first address byte, and acknowledgement and generation of a new transfer direction change (indicated by the TWIMLENbit).

    Please find the attached TWI Code for your reference. We have configured ADSP-21479 as a master and another ADSP-21479 as a slave. Please use this as reference and modify as per your requirement.

    TWI_Master_21479.zip

    TWI_Slave_21479.zip
     
    Regards,
    Lalitha.S

Reply
  • +1
    •  Analog Employees 
    on Apr 4, 2019 6:53 AM

    Hi Jeff,

    As mentioned in the HRM under "Master Mode Addressing" section, whether enabled as a master-transmitter or master-receiver with 7-bit addressing using the TWIMLENbit, the TWI master performs all addressing and data transfers as required. This includes generating the repeated start condition, re-transmission of the 7-bits of the first address byte, and acknowledgement and generation of a new transfer direction change (indicated by the TWIMLENbit).

    Please find the attached TWI Code for your reference. We have configured ADSP-21479 as a master and another ADSP-21479 as a slave. Please use this as reference and modify as per your requirement.

    TWI_Master_21479.zip

    TWI_Slave_21479.zip
     
    Regards,
    Lalitha.S

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