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CC3220MOD: Level shifter is mandatory for interfacing GLCD(5V) and MCU(3.3V)

Naveen K1
Intellectual 870 points
Part Number: CC3220MOD

Hi,

 

We are using CC3220MODSF12MOBR for the IOT project, We are supply 3.3V .

We need to interface GLCD(Parallel Communication, total 12 GPIO's connected) & its VDD required 5V.

My doubt is GLCD is only receives data, it will not transmit any data right? So,

1. Can we directly connect MCU GPIO pins to the LCD without using "3.3V to 5V Level shifter"?

2. If we connect directly without level shifter, Is there any problems to the microcontroller? or It will work efficiently?

 

Kindly recommend with good solutions because its difficult to find 3.3V GLCD & having urgent requirement.

 

Thanks & Regards,

Naveen K

  • 0
    TI__Mastermind 30760 points

    Hi Naveen,

    I think the consideration should be on whether the inputs for the GLCD can work with the logic level from the MCU. If the logic high/low levels of the digital I/Os on the CC3220 are not within spec for the display, I would suggest using a level shifter. Please refer to the datasheet of the GLCD.

    Best,
    Ben M

  • 0 in reply to Benjamin Moore
    Intellectual 870 points

    Dear Ben,

    Thank you very much for your information.

    I have discussed with LCD manufacturer, LCD VDD should be 5V, and it may detect 3.3V level as high.

    But my doubt is we are giving 5V to LCD, So it will not damages to the CC3220 pins right?

    (Because all LCD pins are input only pins, No output pins right)

    PFA the LCD Datasheet.

    Regards,

    Naveen KGT-G12864A-BTSESW(AQ).pdf

  • 0 in reply to Naveen K1
    TI__Mastermind 30760 points

    Hi Naveen,

    Please refer to the CC3220 datasheet regarding I/O attributes and requirements. See sections 4.2, 4.5, and the electrical characteristics for the pins. 

    http://www.ti.com/lit/swas035

    A level shifter is recommended for such a design.

    Best,

    Ben M

  • 0 in reply to Benjamin Moore
    Intellectual 870 points

    Dear Ben,

    Thanks for the information.

    My doubt is, LCD pins only receives data, it will not transmit data right, So it will not damages to the CC3220 pins right? So level shifter not required right?

    Regards,

    Naveen K

  • 0 in reply to Naveen K1
    TI__Genius 15590 points

    Hi Naveen,

    Although I agree that using a level-shifter is probably the best/safest option,...as long as your LCD can detect 3.3V as a level high, and you're meeting the I/O requirements from the CC3220 datasheet, then this should be ok.

    Thanks,

    Alexis

  • 0 in reply to Alexis Crandall20
    Intellectual 870 points

    Hi Alexis,

    Thank you for the information.

    1.Series Resistor is required for Microctroller GPIO’s to increase the micr0controller life?

    Some peoples are suggesting to use 1KOhm series resistor to connect microcontroller-GPIO’s with onboard/External communicating devices.

    Examples: Connect 1K series Resistor from

    1. MCU1 UART pin to MCU2 UART pin,
    2. MCU(Microcontroller) to LCD
    3. Amplifier Output pin to Microcontroller pin.
    4. Optocoupler output pin to Microcontroller pin, etc....

    2. GPIO pins required series resistor to protect or increase the life of the microcontroller. Is it true? Could you suggest series resistor?

    Thanks and Regards,

    Naveen K

  • 0 in reply to Naveen K1
    TI__Genius 15590 points

    Hi Naveen,

    No series resistors are not required for the GPIO interface...although it is common to use 22Ohm series resistors to help with signal integrity. 

    Thanks,

    Alexis