I wish to send data back-and-forth between a Master and one of a few dozen slaves within a mesh-network style arrangement.
Assume that all units are (identical) microcontrollers within my control, i.e., can be programmed. In the interest of maximizing data throughput to several hundred kb/s, I am considering SPI.
Are there any strategies or existing implementations to achieve such a topology while using only 1 or 2 pins/signal-lines in total, aside from MOSI, MISO, and CLOCK?
These 1 or 2 pins could be for a custom handshaking or slave-selection method, however what I don't want to do is spend one pin per EACH slave (or use multiplexing) due to some constraints, including the wiring arrangement and limited physical space on the hardware of each master and slave.
I see I2C raising its hand here, but would like to maintain the advantages of SPI (e.g., simplicity and much faster data transfer). I expect throughput would decrease somewhat in this kind of bus implementation especially if I use software-addressing/polling, but perhaps there is some smarter solution to not drag it down too much?