Status of push button attached at pin 2 is read. Two variables are defined m_send and m_receive. In this section we have performed actual operation on instruction sending and receiving. Then SPI communication has been setup using functions described above and slave select has been set high to discontinue the communication if being performed already.ĭigitalWrite(SS,HIGH) Function performed The push and LED pins have been declared as input and output pins. Here device is being setup for program and communication. LED variable is the Arduino pin where based on data received from slave device output status will be shown. Push variables are the Arduino digital I/O pin where the push button will be connected and depending upon its status, Data will be transmitted to the slave device. In this section, we have included the SPI library and defined different variables. Arduino SPI Master Device CodeĬode can be divided into 3 parts: Declarations Now let us understand the code of the Master device.

To enable SPI communication between the two boards, connect the SPI pins of master Arduino with the SPI pins of the slave Arduino.When pushbutton is not pressed, logic low will appear on pin 4 or push button state will be low and when the push button is pressed, a logic high will be on pin 4. The other end of the resistor is connected with a ground. Next, the push button’s one terminal is connected with 3.3 volts of Arduino and other terminals of a push button is connected with Arduino digital pin 4 through 10k pull-down resistor.In the above circuit diagram, for both the Master and the Slave, Arduino digital pin 4 is connected with anode pin of LED through a 220 ohm current limiting resistor.These dividers correspond to division with values of 2, 4, 8, 16, 32, 64, 128. SPI.setClockDivider(divider): It set the SPI clock divider in accordance with the system clock.įollowing types of divider are available here:.SPI.attachInterrupt(handler): It is used to receive data from a master device in a slave device and is called in a slave device.SPI.transfer(val): This is used for simultaneous communication between Master and Slave devices.SPI.begin(): It initializes the SPI bus and sets the SCK and MOSI pin to LOW and SS pin to HIGH.: It includes the library in the program to use the function of SPI communication.

In order to establish communication between two Arduino using SPI, there is a pre-built library of Arduino used for this purpose

But before that let’s understand the SPI communication library functions which are available in Arduino IDE. Now let’s see an example of SPI communication between two Arduino boards.

Serial to spi arduino