Spi arduino controller code#

This is because the SPI hardware can be used to communicate with a number of slaves at once. There is a bit of confusion about the Slave Select pin.

Spi arduino controller code#

The code to produce this (in Arduino's C++ language) was: Also the slave should ignore any clock pulses now (they may be for a different peripheral). At this stage the slave should release the MISO line (configure it as an input, or 'high impedance'). G - SS taken high to indicate end of the sequence of data.F - 'No data' after 'Fab' - however the SS is still enabled.Also the slave can place data on the MISO line for the master to simultaneously read in. This tells the slave to read the data on the MOSI line.

For each of the 8 bits the SCK (clock) line is briefly brought high, and then low again.

C - First character arrives (the letter 'F' or 0x46 or 0b01000110).

The slave can now prepare to notice clock pulses on the SCK line.

At this point the slave should prepare to transfer data by setting the MOSI (master out, slave in) line, and the SCK (serial clock) as inputs, and the MISO (master in, slave out) as an output.

B - SS taken low to enable the slave (peripheral).

I put a trigger on the SS (Slave Select) pin so that the logic analyser would start analysing from when the sequence started.įrom the above graphic note the following points of interest: It shows the 3-character sequence 'Fab' being sent from the Arduino. Let's start with an image - this is a screenshot taken with a logic analyser.