#SHIFT REGISTER USING SPI ARDUINO CODE#
The main loop function is actually pretty simple and the code is similar to the one in the previous post.įirst of all, we set the SS pin to LOW, in order to avoid internal transference of data between the shift register and the storage register of the SN74HC595 while we are sending the 8 bits from the microcontroller to the integrated circuit. Nevertheless, the frequency can be changed with the setFrequency method. Note: The SPI clock is initialized with a value of 1 MHz, as can be seen here in the implementation of the begin method. Since we are using a GPIO pin for as Slave Select (SS), we declare it in a global variable.įinally, in the setup function, we define the SS pin as an output pin and we initialize the SPI bus with the begin method. You can check the implementation of this library for the ESP8266 here. In this case, we need to include the SPI library, which provides easy to use functions to interact with devices using this interface. You can read a more detailed explanation about the connection between the SN74HC595 and the ESP8266 in this previous post.
You can check the mapping of the SPI pins in the ESP8266 on this article. It’s equal to the one shown in the previous post about controlling the device using the shiftOut function, except for the fact that now we are using the SPI pins of the ESP8266.įigure 1 – Connection diagram between the ESP8266 and the SN74HC595, for data transfering using SPI. The schematic for controlling the SN74HC595 via SPI is shown in figure 1. You can check a great article about the SPI interface here. You can check here how to configure the Arduino IDE to support the ESP8266.Īlthough this tutorial was tested using the SN74HC595 from Texas Instruments (datasheet here), it’s expected to work with versions of the 74HC595 from other manufacturers. We assume the use of the ESP8266 libraries for the Arduino IDE.
#SHIFT REGISTER USING SPI ARDUINO HOW TO#
An explanation on how to control some LEDs using this method is also included. The objective of this post is to explain how to transfer data between the ESP8266 and the SN74HC595 using the SPI interface.
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