The Particle Core does not support the SPI.transfer(buffer, size) from the Arduino SPI reference:
If I’m looking in the correct place, this is the current implementation:
https://github.com/particle-iot/device-os/blob/1b1805fb4afcb93b0e92fbecfd28c082d6310285/wiring/src/spark_wiring_spi.cpp and the method isn’t in there.
This will cause a current and future incompatibility with any library that uses this method. The most important one of these will be the Adafruit BusIO library: https://github.com/adafruit/Adafruit_BusIO It looks like Adafruit created this library in March to alleviate SPI and I2C problems like this. In this case it actually highlights that Particle boards will not be able to use Adafruit code in the future unless this is fixes as it looks like Adafruit is adding this to several code bases.
The Adafruit code is missing a define for the SPARK, but that’s a simple pull request. So - before I submit this as an issue on https://github.com/particle-iot/device-os/ - is this on purpose or just something that got lost?
I can work my way around this, but this will be a showstopper for many when they get the error: “error: no matching function for call to ‘Adafruit_SPIDevice::transfer(uint8_t*&, size_t&)’”