The NeoICSerial documentation contains a table that states for the Uno:

  • Transmit: 9
  • Receive: 8
  • PWM Unusable: 10

Pin 8 and 9 are used for the serial connection. Pin 10 is part of the pins for the SPI on the Uno. Does this mean SPI connections can't be used together with NeoICSerial or is this specific for using pin 10 for PWM?


The "Unusable 10" is explained in AltSoftSerial library

The "Unusable PWM" pins can be used normally, with digitalRead() or digitalWrite(), but their PWM function controlled by analogWrite() will not work properly, because AltSoftSerial uses the timer which controls that pin's PWM feature.

Pin 10 on Uno is SPI slave select if the Uno is SPI slave (then it is an INPUT).

If the Uno is SPI master, this pin must be set as OUTPUT. For this reason it is usual to use pin 10 as slave select for the (first) SPI slave. SPI shields have this pin hardwired as slave select for the (first) SPI device on the shield.

  • NeoICSerial is interrupt driven - does this create a limitation between using pins 8, 9 and 10? I'm a bit puzzled by the table in the documentation and don't see where the limitation is coming from. The documentation states: "This class can only use one predefined Input Capture pin. Each MCU and board has a pre-determined pin" Mar 15 '19 at 19:04

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