I2C

Question 1

What are the two wires in I2C?

Answer 1

> SDA (Data)

> SCL (Clock)

Question 2

How long is a packet?

Answer 2

8 bits

Question 3

How is each bit transferred over SDA?

Answer 3

On a clock edge

Question 4

What is the start sequence?

Answer 4

SDA goes low while SCL goes high

Question 5

What is the stop sequence?

Answer 5

SDA goes high while SCL goes low

Question 6

What is the general structure for a 1-byte tranaction?

Answer 6

[Picture2]

Question 7

How does the receiver acknowlege a bit has been recieved?

Answer 7

By holding the SDA line LOW for one clock cycle

Question 8

How long is an I2C address?

Answer 8

7-bits

Question 9

What is the 8th bit when an address is being sent?

Answer 9

The direction.
0 = writing
1 = reading
e.g.
AAAAAAA1

Question 10

What is the process for reading from a slave?

Answer 10

1. Master transmits slave address with write direction
2. The slave acknowleges the by holding the line low for one clock cycle
3. The master transmits the register the slave must transmit
4. the master continues to clock the SCL allowing the data to be recieved by the master
5. The master sends a stop condition after the 8-bits have been recieved

Question 11

What type of architecture is I2C?

Answer 11

Master-slave

Question 12

How many slaves can be connected to an I2C bus?

Answer 12

2^7 - 1 = 127

Question 13

What is address 0 on an I2C bus?

Answer 13

Used to address all slaves

Question 14

What can also limit the number of slaves on an I2C bus?

Answer 14

Number of devices is limited by capacitive loading of the lines

Question 15

What makes I2C more robust than UART?

Answer 15

Because it has acknowlegments

Question 16

What is the process for reading multiple values from a slave?

Answer 16

It is possible to read a burst of values from multiple registers if the slave is configured to do so.
If the master continues to clock the SCL line then the slave will continue sending data

Question 17

What is the process for writing values to a slave?

Answer 17

1. Master transmits slave address with write direction
2. The slave acknowleges the by holding the line low for one clock cycle
3. The master transmits the register the slave must write to
4. the master continues to clock the SCL and transmits the data to the slave
5. The master sends a stop condition after the bits have been sent

Question 18

What is the process for writing multiple values to a slave?

Answer 18

This is done in a similar way to burst reading