# How do you calculate I2C pull ups?

## How do you calculate I2C pull ups?

These pull-ups would draw 3.3V / 1.77 k = 1.86 mA each when SCL / SDA is low. So, theoretically, if this bus has the absolute maximum amount of capacitance on it, this bus should use at least 1.77 k Ohm pull-up resistors, down to 171 Ohm resistors if their maximum low drive strength is 13.5 mA each during SCL/SDA low.

## How is I2C bus capacitance calculated?

To calculate the bus capacitance simply add up all the area of the traces, the distance to ground and the dielectric and calculate away. So yes it is not simple to do. 2. It is in the i2c spec.

How do you calculate frequency of SCL?

The SCL serial bit clock frequency is equal to the divided by the divider. The frequency divider value can be changed at any point in a program.

### What is the speed of I2C bus Mcq?

What is the speed of I2C bus? Explanation: Common I2C bus speeds are the 100 kbits/s standard mode and the 10 kbits/s low speed mode, but arbitrarily low clock frequencies are also allowed. -> Slave receive – Slave node is sending data to master.

### What is rise time in I2C?

The I2C protocol dictates the maximum allowed rise times based on the maximum clock frequency used. In version 2.6 of the I2C specification, the maximum rise time for standard mode and fast mode is 1,000 ns and 300 ns, respectively.

What is I2C bus capacitance?

I2C bus capacitance. Bus capacitance is a collection of individual pin capacitance with respect to ground, the capacitance between the SDA and SCL, parasitic capacitance, capacitance added by the devices hanging on the bus, bus length (wire), dielectric material, etc.

## What is SPI frequency?

9.3. 4.1 Serial Peripheral Interface (SPI)

SPI0CLK SPI Frequency (kHz)
2 125000
4 62500
8 31250
16 15625

## How Slow Can You Run I2C?

Theoretically minimum I2C speed is 0Hz as per I2C specification.

What is I2C hold time?

Hold Time For Start Condition (tHD;STA): is the minimum time the data should be low before SCL goes low. It is measured as the time taken from 30% amplitude of SDA from a HIGH to LOW transition to 70% of the amplitude of SCL from a HIGH to LOW transition.

### How is SPI speed calculated?

Therefore if the CPU is fully utilized the SPI will transfer one byte (8 clocks) every 200 system clock cycles. 200 * sysclk = 8 * spiclk; spiclk = sysclk/25; We can see that in this example the maximum SPI rate is determined by the CPU’s ability to service the SPI data.

### What is faster I2C or SPI?

I2C is a two wire protocol and SPI is a four wire protocol. I2C supports clock stretching and SPI does not have clock stretching. I2C is slower than SPI.

How do you calculate SPI speed?