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Discussion in 'Microcontrollers, Programming and IoT' started by pavankukkala, Jan 19, 2018.

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  1. pavankukkala


    Mar 25, 2014
    My friend have attended the interview on last week. I didnot able to solve the answers for some of the questions . can you please help me.

    1. How the CPU,RAM are logically connected with SPI and I2C?
    2. Which software is used to connect with SPI and I2C peripherals?
    3. What's the mechanism to transfer data between SPI and I2C?
  2. Harald Kapp

    Harald Kapp Moderator Moderator

    Nov 17, 2011
  3. Gumby_Kevbo


    Jan 25, 2018
    It has been 20 years give or take since I used any , but Phillips used to make some 256 byte i2c static ram chips in a dip-8, and microchip made a NVRAM (flash?) with a SPI interface...pretty sure it also came with i2c if you wanted that. The phillips static rams used next to nothing in standby, so I was using a watch battery to make them NV. That battery also ran a RTC chip, which was also on the i2c bus.

    Many microcontrollers these days have on-board NVRAM and/or micro-power standby modes that retain memory, so there is not the need for outboard NVram that there used to be.

    If you only have a couple of chips you need to talk to, SPI works fine and is fast. If you need to talk to a bunch of chips, then the chip enable lines needed for SPI start burning up lots of I/O pins, so i2c starts to make more sense.
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