Do I need to buy hardware for this tutorial?

No. Everything runs in the browser: Circuitly simulates the board, the components and the code. Real hardware is optional if you want to rebuild the circuit afterwards.

Which components are used?

Arduino UNO board, ST7789 TFT display (SPI), Lecteur carte SD. They are already available in the simulator library.

How long does it take?

About 20 minutes, advanced level, in 4 guided steps.

What should I know before starting?

The previous tutorial in the series, “Programmable alarm clock (RTC)”, is enough preparation. No software install is required.

Is the code provided and checked?

The simulator checks your wiring and your code automatically at every step, and shows the commented solution if you get stuck.

All tutorials

4 · Displays & buses

Understanding the SPI bus

Advanced20 min

Goal

Exchange a byte as SPI master and observe the 4 wires.

Why it matters

MOSI, MISO, SCK, CS: SPI is full-duplex, unlike I²C.

What you need

Arduino UNO board
ST7789 TFT display (SPI)
Lecteur carte SD

Nothing to buy: every component below is simulated in the browser.

Steps

01Add an SPI peripheral (TFT or SD card).
02SPI.begin() inside setup(), CS as OUTPUT.
03Pull CS low, send SPI.transfer(0x9F), raise CS.
04Print the answer in hexadecimal.

This tutorial runs inside the Circuitly simulator: your wiring and your code are checked automatically at every step.

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Frequently asked questions

Do I need to buy hardware for this tutorial?: No. Everything runs in the browser: Circuitly simulates the board, the components and the code. Real hardware is optional if you want to rebuild the circuit afterwards.
Which components are used?: Arduino UNO board, ST7789 TFT display (SPI), Lecteur carte SD. They are already available in the simulator library.
How long does it take?: About 20 minutes, advanced level, in 4 guided steps.
What should I know before starting?: The previous tutorial in the series, “Programmable alarm clock (RTC)”, is enough preparation. No software install is required.
Is the code provided and checked?: The simulator checks your wiring and your code automatically at every step, and shows the commented solution if you get stuck.

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