Automatic cascaded address selection

1. An apparatus for addressing electronic circuits, comprising:

a host device comprising an address output; and

a plurality of addressable electronic circuits, each comprising an address input, an address selection input and an address selection output, wherein the plurality of addressable electronic circuits are connected serially with each pair of the serially connected addressable electronic circuits connected by the address selection input and the address selection output,

wherein each of the addressable electronic circuits further comprises a reset input and a reset output, each reset output being connected to a reset input of a following one of the addressable electronic circuits,

wherein each of the addressable electronic circuits releases a respective reset output to release the reset input of the following one of the addressable electronic circuits when the address selection input of the following one of the addressable electronic circuits is stable, and

wherein, upon release of the reset input, the following one of the addressable electronic circuits sets a signal at the address selection input as a unique address.

2. The apparatus of claim 1 , wherein each of the addressable electronic circuits is configured to output a different address value at its address selection output than it receives at its address selection input.

3. The apparatus of claim 1 , wherein each of the addressable electronic circuits is configured to receive an address value at its address selection input, to increment the address value yielding an incremented address value and to output the incremented address value at its address selection output.

4. The apparatus of claim 1 , wherein each of the addressable electronic circuits is configured to receive a unique address at its address selection input to be used to identify that one of the addressable electronic circuits.

5. The apparatus of claim 1 , wherein each of the addressable electronic circuits is configured to receive an address value at its address selection input and to compare the address value with a received address value at the address input.

6. The apparatus of claim 1 , wherein the address input on each of the addressable electronic circuits comprises a serial bus input.

7. The apparatus of claim 1 , wherein the address input on each of the addressable electronic circuits comprises an I2C data input.

8. The apparatus of claim 1 , wherein each of the addressable electronic circuits further comprises a clock port and wherein the host device further comprises a clock port, wherein the clock port on each of the addressable electronic circuits is connected to the host device clock port.

9. The apparatus of claim 8 , wherein each of the addressable electronic circuits is configured to hold its clock port in an inactive state until it has been configured with a unique address at its address selection input.

10. The apparatus of claim 9 , wherein the host device is configured to wait to use its address output until its clock is released from the inactive state by all of the addressable electronic circuits.

11. The apparatus of claim 1 , wherein the address output of the host device comprises an I2C serial data line and wherein the clock port of the host device comprises an I2C serial clock line.

12. The apparatus of claim 1 , wherein each of the addressable electronic circuits is configured to latch in a unique address at its address selection input when a corresponding reset input is released.

13. The apparatus of claim 1 , wherein the address selection input of a first of the serially connected addressable electronic circuits is hardwired to a unique address.

14. The apparatus of claim 1 , wherein the address selection inputs of all but a first of the serially connected addressable electronic circuits are configured to unique addresses by the address selection output of a preceding one of the addressable electronic circuits in a serial chain.

15. The apparatus of claim 1 , wherein the address selection output of each of the addressable electronic circuits comprises a general purpose input/output port.

16. The apparatus of claim 1 , wherein the address selection output of each of the addressable electronic circuits comprises a digital to analog converter output, and wherein the address selection input of each of the addressable electronic circuits comprises an analog to digital converter input, and wherein a unique address for each of the addressable electronic circuits is represented by a unique voltage level from the digital to analog converter outputs.

17. The apparatus of claim 1 , wherein the address selection input of each of the addressable electronic circuits is configured to identify least significant bits of unique addresses and wherein each of the addressable electronic circuits is internally configured with a same set of most significant bits of the unique addresses.

18. A method for addressing electronic circuits, comprising:

in a serial chain of a plurality of addressable electronic circuits, all but a first of the addressable electronic circuits receiving at least a portion of a different unique address from a preceding one of the addressable electronic circuits;

each of the addressable electronic circuits releasing a reset signal to a following one of the addressable electronic circuits upon outputting one of the different unique addresses for the following one of the addressable electronic circuits, wherein the releasing the reset signal sets the following one of the addressable electronic circuits with the unique address received from the preceding one of the addressable electronic circuits;

each of the addressable electronic circuits holding a status signal in an inactive state until it has received its unique address; and

a host device transmitting an address and data to at least one of the addressable electronic circuits after all of the addressable electronic circuits have released the status signal from the inactive state.

19. The method of claim 18 , wherein the status signal comprises a clock signal of a bus connected to the plurality of addressable electronic circuits.

20. A system for assigning unique addresses to each of a plurality of electronic circuits, comprising:

means in each of the plurality of electronic circuits for reading one of the unique addresses at an address selection input when a reset input is released;

means in each of the plurality of electronic circuits for calculating another of the unique addresses based on the unique address at the address selection input; and

means in each of the plurality of electronic circuits for signaling when the unique address at the address selection input has been read,

wherein the reset input is released based on a reset signal received from a reset output of a preceding one of the plurality of electronic circuits.