You are reading a single comment by @Gordon and its replies.
Click here to read the full conversation.
Espruino is a JavaScript interpreter for low-power Microcontrollers. This site is both a support community for Espruino and a place to share what you are working on.
@Gordon
That's really interesting. Which pin are you using? And you're on the MDBT42Q with 1v99 firmware?
I actually hooked it up to a scope before posting to check it was doing the right thing, and I see the opposite of you (0v normally on mosi with 4 pulses) so I'm very surprised it's got inverted somehow.
There is the ~30uS gap between pulses as you note, but looking at the datasheet that should be ok.
SPI should normally transmit most significant bit first, so if the lowest bit is 0, that should be the state the MOSI line is left in...