ADS7138: HIGH SPEED SUPPORT

Moses Savariyar

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.

over 1 year ago

0 Joel Meraz over 1 year ago

TI__Mastermind 19230 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 Moses Savariyar over 1 year ago

Intellectual 440 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 Moses Savariyar over 1 year ago in reply to Moses Savariyar

Intellectual 440 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 Joel Meraz over 1 year ago in reply to Moses Savariyar

TI__Mastermind 19230 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 Moses Savariyar over 1 year ago in reply to Joel Meraz

Intellectual 440 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 Joel Meraz over 1 year ago in reply to Moses Savariyar

TI__Mastermind 19230 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

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ADS7138: HIGH SPEED SUPPORT