Wire.onReceive never getting called, but Wire.onRequest works fine

[ScruffR]

This sounds a bit like this previous question

Photon as I2C slave - can only read reg 0

Hi, I have set up my photon as i2c slave, using Wire lib. The slave has data : uint32_t registers[2], i.e 8 bytes, that the master wants to read. In setup I register a callback for the Wire.onRequest(). The callback (which takes no parameters) writes all 8 bytes using Wire.write(registers, 8). The callback which is registered with onRequest does not accept parameters, so I guess I have to dump all register bytes in the write() call even if the master requests less. On Raspberry pi 3 I use …