7 years, 6 months ago.

Special port expander question

Dear Developers,

I'm in a slightly complicated situation, which can be shortly described.

I have a 30×32 matrix, each element is an individual solenoid type linear actuator. All elements must be driven directly and individually based on a strict pattern. The actual prototype is using four MCP23017 i2c port expanders, and all elements connected in a multiplexed matrix (with darlingtons and transistors) and works flawlessly. The problem is simple: the actuators must be in "closed" state continuously for a long time (from 0,3 to 1,2 seconds, depends on the pattern), for each line of the matrix. That means, at least 0,3 × 32 = 9,6 seconds needed for a single round, but it may be up to almost 40 seconds, which is too long.

My idea for the next step is to drive each row (or column) of the matrix with an individual set of port expanders (for example, 2 MCP23X17 may be enough for a single line), and forget the multiplexed connection. Unfortunately only 8 drivers can be daisy-chained with individual addresses. M'kay I can drive one set on i2c and another on SPI, but it's till only 16, which is not enough (yet not elegant).

The question: is there any suggestion for a port expander to use which can drive all 960 lines independently? (I reached PCA9635 LED drivers which is addressable up to 126 drivers on a single i2c line.)

Any suggestion, please?

Thanks in advance,

Tamás