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Original question:

ADS7138: Configure to high speed mode

ADS7138: HIGH SPEED SUPPORT

Moses Savariyar
Prodigy 30 points
Part Number: ADS7138

Tool/software:

In this case, for every I2C sequence that consist of Start and Stop, do we need to send those opcodes for making it work on high speed?

We need I2C communication to work in 400Khz all the time with ADC7138.

  • 0
    TI__Expert 3910 points

    Hi Moses,

    Apologies for the delay in communications. I believe Rahul describes the operation quite well in the thread that you included. The ADS7138 will continue operating in fast mode (400kHz SCL) until the MCU sends a stop condition. This is simply inherent to the I2C protocol itself. The ADS7138 is unable to enter fast mode by itself upon power up.

    As long as the MCU has sent a fast mode master command, and there hasn't been a STOP condition sent by the controller, then the device will continue operating in fast mode.

    Regards,
    Joel

  • 0
    Prodigy 30 points

    Joel,

            Thanks for the reply. My intention of this specific question was as we need to include the specific opcode for every sequence that we are gonna transmit, Then it will introduce additional overhead to the Sequences right? we have strict timeline to complete the init sequence or for run time process over the i2c communication. i have not seen such opcode sending to change the speed in any other i2c devices. it will work automatically with clock stretching's as per the standard i2c communication.

  • 0 in reply to Moses Savariyar
    Prodigy 30 points

    So if we are sending 8 sequences READ/WRITE, then it  needed 8 times to send opcode? this was my original question for this overhead.

    Also i see there are modes as below.

    standard-mode, fast-mode, fast-mode plus, and high-speed mode.

    Bu default Device will only work on Standard Mode (100Khz) and for other modes we need to send opcode?

  • 0 in reply to Moses Savariyar
    TI__Expert 3910 points

    Hi Moses,

    I was mistaken in my previous reply. The ADS7138 supports fast mode (400kHz) by default. It only requires special configuration to enter high-speed mode (3.4MHz). You will be able to run the device at 400kHz the entire time. This is specified in footnote 1 under the I2C timing requirements section. Apologies for the confusion.

    Regards,
    Joel

  • 0 in reply to Joel Meraz
    Prodigy 30 points

    Thanks but we facing some issues when we continue to operate in 400Khz, let us double check and confirm, Thanks for the reply

  • 0 in reply to Moses Savariyar
    TI__Expert 3910 points

    Hi Moses,

    Can you clarify the nature of the issues you're running into? We might have some resources that may be able to help with that!

    Regards,
    Joel