For prototyping purposes, a clock rate of 500 kHz is suitable, although the AMT22 supports rates up to 2 MHz. Achieving 500 kHz can be done using the SPI_CLOCK_DIV32 setting. Given the Arduino Uno’s 16 MHz clock, this division results in a 500 kHz SPI clock rate. For more details on SPI clock configuration, consult Arduino documentation. After configuring everything, the SPI bus can be initialized using SPI. begin(), which will set up the three dedicated SPI pins: MISO, MOSI, and SCLK, preparing the system for communication with the encoder. SPI Communication SPI communication with the AMT22 is handled through the Arduino's SPI library, while the chip select (CS) control is managed through the code using digital I/O pins. The digitalWrite() function is used to assert or deassert the CS line (Listing 3).
Initialization In the setup() function (Listing 2), begin by initializing all required SPI pins and configuring the serial interfaces for communication. The serial port should be initialized to allow data transmission to the host computer. This is done by
passing the defined BAUDRATE into the Serial.begin() function. Before enabling SPI, ensure the chip select (CS) line is set to the appropriate state to prepare the encoder for communication. Select a clock rate for the SPI bus to communicate with the AMT22.
Listing 2: The setup() function which initializes the all SPI pins.
Listing 3: Setting up SPI communication.
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