Low power high digital I/O count microcontroller

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ayates
 
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Low power high digital I/O count microcontroller

Post by ayates »

New to the current microcontroller space... The last time I played in this area was the days of the 6502 and 6809 with assembler code :)

I'm considering a project where low power is a requirement, along with a large number of digital inputs and outputs; approximately 24 inputs and 36 outputs, where 33 of the outputs would be driving 3mA LEDs @ 12 VDC, I would like to program in some type of higher level language, but the actual logic will be quite simple.

There are so many options these days, I was wondering if anybody had some suggestions to point me in a good direction?


Thanks,

Allan.

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adafruit_support_mike
 
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Re: Low power high digital I/O count microcontroller

Post by adafruit_support_mike »

By definition a system with 33 x 3mA x 12V = 1.2W or a hair less. The microcontroller will probably use less tha 100mW (20mA @ 5V). We’re used to think of low power as the TPL5110 timer that uses about 100nA @ 3.3V.

From your pin descriptions, that sounds like the kind of system where we’d export much of the IO to external devices. The TLC5947 LED driver has 24 channels, for instance:

https://www.adafruit.com/product/1429

Daisy-chaining a couple of those would give you plenty of LED control and take a lot of processing load off the microcontroller.

In a similar way, we have the MCP23008 and MCP23017 GPIO expanders:

https://www.adafruit.com/product/593
https://www.adafruit.com/product/732

Those have 8 and 16 pins that you can assign (individually) as input or output. You can use up to 8 of them together for a maximum of 128 IO pins. You do have to poll the chips to get input from them, but in many cases that’s okay.

Between those and the TLC547, you’d use 5 microcontroller pins: three for SPI communication with the TLC5947, and two for I2C communication with the MCP240xx GPIO expanders.


If you want to keep everything in the microcontroller, the Grand Central has a total of 70 IO pins:

https://www.adafruit.com/product/4064

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