I'm using an Arduino due (3.3V) to drive some daisy-chained SPI DAC's (mcp4822). I use only three cables a MOSI, SCK, and CS (chip select). I'm using just one SPI channel and I select the active module with the CS signal.
The pins of Arduino are capable to deliver "3 mA or 15 mA, depending on the pin, or receive (sink) a current of 6 mA or 9 mA, depending on the pin". Maximum current consumption for all pins connected to the micro-controller 150mA.
The MCP4822 "absolute maximum rating" Current at Input Pins ±2mA Current at Supply Pins ±50mA Current at Output Pins ±25mA
Input-current: 415 (typical) 750 (maximum) μA
So my question is when daisy chaining modules does the current draw raises and if I connect around 6 modules will it damage the pins (I mean the MOSI and the SCK pins )?
Are the SPI pins of Arduino Due connected directly to the microprocessor, or is it a peripheral?
If that is the case should I use a resistor to limit the current?
And one last: if 6 modules would work ok, can I expect the same when connecting 15 or 30 modules (I mean in this fashion i.e. a MOSI and SCK that is connected serially to all modules and only different CS connections to each one).