I2C AND SPI

[pavankukkala]

HI,
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?

 

[Harald Kapp]

3. I2C and SPI are serial bus protocols.
2. ??? You can write your own or use libraries. I do not understand the question.
1. I'm not aware of RAM with SPI or I2C interfaces - though that may exist. For any component to be attached to a cpu via SPI or I2C you need an SPI or I2C interface.

https://en.wikipedia.org/wiki/I²C
https://en.wikipedia.org/wiki/Serial_Peripheral_Interface_Bus

 

[Gumby_Kevbo]

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.