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Original question:

PGA900 about M0

PGA900: PGA900 transmit ADC data under M0 reset mode by I2C

GibsonR8
Prodigy 220 points
Part Number: PGA900

Hello , I have some questions about PGA900 data transmition.

Here is a related question i found in E2E.In this reply, I mentiond "can also use the Communication Buffer COMBUF feature of the device to get calibrated ADC values without having to put the device into reset every time."

First question is I want to know how to use the Communication Buffer COMBUF in my firmware code?

Here is part of my code , I declare 3 variables to store PADC_DATA. But how should I know this 3 variables are in Communication Buffer COMBUF so that they can be communicated by digital interface when M0 is running?

Second question is how to make an external MCU like STM32 to read PGA900's PADC data by I2C.I read the datasheet, i'm still confused about PGA900's I2C slave address and how to operate this function in my firmware?

  • 0
    TI__Mastermind 31655 points

    Hello Gibson,

    The COMBUF is separate from the UART capabilities. The COMBUF is a group of registers that is able to be read/written while the M0 is running, so commands can be taken in and data read out depending on how it is configured in the firmware. You can find a detailed explanation in the datasheet under the section "Accessing PGA900 Memories While Microprocessor is Running." The example firmware does not include specific code demonstrating the COMBUF use, but there are .c and .h files meant to house the functions.

    I2C communication is also described in detail in the I2C Communication section of the datasheet including examples of I2C transactions. The PGA900 memory is broken up into pages, and each page has its own address (see below). Each page essentially acts like a separate device on the I2C bus. When you access a specific register, you will have to confirm which page it belongs to and write to the proper address from the table below.

    Regards,

    Scott