Do not influence state of SS if it's already been set to an output previously, e.g. by user sketch
squashes and closes PR #2659
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@ -29,7 +29,15 @@ void SPIClass::begin()
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noInterrupts(); // Protect from a scheduler and prevent transactionBegin
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if (!initialized) {
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// Set SS to high so a connected chip will be "deselected" by default
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uint8_t port = digitalPinToPort(SS);
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uint8_t bit = digitalPinToBitMask(SS);
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volatile uint8_t *reg = portModeRegister(port);
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// if the SS pin is not already configured as an output
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// then set it high (to enable the internal pull-up resistor)
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if(!(*reg & bit)){
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digitalWrite(SS, HIGH);
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}
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// When the SS pin is set as OUTPUT, it can be used as
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// a general purpose output port (it doesn't influence
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