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I2C Daisy Chain Addressing with Multipurpose Interrupt Disclosure Number: IPCOM000235047D
Publication Date: 2014-Feb-25
Document File: 2 page(s) / 41K

Publishing Venue

The Prior Art Database


Disclosed is a method to perform I2C daisy chain addressing with multipurpose interrupt as a means of expanding the address range on the bus.

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I2C Daisy Chain Addressing with Multipurpose Interrupt

Most I2C parts have a limited address range. The address range is usually defined by hardware (HW) pin straps. This limits the number of I2C address that can be on the same bus. Increasing the address range of an I2C device usually requires additional HW pins.

This solution uses two (2) HW pins, enabling the utilization of the entire range of I2C addresses for as many devices on the one I2C bus. With this method, 10 of the same I2C input/output (I/O) expanders can be used on the same bus using only two (2) address pins; current methods take four (4) address pins. These two (2) HW pins, after setting the I2C address power on, are multipurpose and act as an interrupt pin after address initialization, further reducing the number of pins needed. Every I2C device has an Address In/Interrupt Out pin and an Address Out/Interrupt In pin. All of the I2C devices have these pins connected in a daisy chain format.

To implement the method in a preferred embodiment:

1. At power on/reset, the first device sees the rising edge on the address in pin

2. After a set time, the first device sends out a pulse on the address out pin

3. When the second device sees the single pulse on the Address In pin, it increments its I2C address by one bit

4. Once the second device's address is modified, it send out two pulses on the Address out pin

5. This process is repeated until all devices have had the associated I2C address incremented