SPI.transfer(0x12) // Send second byte // HEX 0x12 = DEC 18 SPI.transfer(36) // Send first byte // DEC 36 PinMode(CS_Pin, OUTPUT) // The CS_Pin should remain in a high impedance state (INPUT) when it is not in use.ĭigitalWrite(CS_PIN, LOW) // Activate the CS line (CS is active LOW) Finally, we release the CS line to end the transmission and deactivate the slave. We have to activate the chip select (CS) line to activate the slave that we want to communicate with, then we can transmit data. When we use SPI, it is a pretty manual operation. SPI.begin() // Initialize SPI - 4000000 Baud, MODE0 (default) Transmitting The default SPI configuration is a baud rate of 4MHz in Mode 0. The SPI.begin() function does not require any arguments. This must be done before using any other SPI functions usually in setup(). To initialize the SPI library, use the SPI.begin() function. Go to the Sketch Menu -> Include Library -> SPI. To begin, you must include the SPI library in your sketch.
A 4.7k to 10k resistor from each SS to Vcc should be adequate. The communication lines are driven high and low by the devices, while the SS lines require pull-ups to ensure that they return to the inactive state. This means that SPI requires 3 + N wires, where N is the number of slaves on the bus. In addition to these three lines, each slave also has its own slave select line connected directly to the master. HardwareĪll of the devices on an SPI bus share the MOSI, MISO, and SCK lines. The master runs the serial clock (SCK) line and with every pulse, the master sends and receives a bit and the slave sends and receives a bit.
This means that data travels in both directions at the same time on every clock pulse. SPI operates in a synchronous, full-duplex mode. In addition to the SS line, SPI uses three lines for communication Master In Slave Out (MISO), Master Out Slave In (MOSI), and the serial clock line (SCK). The SS line is active low and usually, has a pull-up to ensure that the line returns high in an idle state. The master differentiates between the slaves by activating the appropriate slave device with a slave select (SS) or chip select (CS) line. The protocol allows one master per bus and many slave devices. SPI is intended for communicating over short distances at relatively high speeds. Serial Peripheral Interface, or SPI, was developed in the late 1980’s and was quickly adopted as the standard communication protocol for embedded systems.
0 kommentar(er)
