SPI
This content relates to a deprecated version of Mbed
Mbed 2 is now deprecated. For the latest version please see the Mbed OS documentation.
For the latest SPI API, please see SPI.
The SPI Interface provides a "Serial Peripheral Interface" Master.
This interface can be used for communication with SPI slave devices, such as FLASH memory, LCD screens and other modules or integrated circuits.
Hello World!¶
Import program
00001 #include "mbed.h" 00002 00003 SPI spi(p5, p6, p7); // mosi, miso, sclk 00004 DigitalOut cs(p8); 00005 00006 int main() { 00007 // Chip must be deselected 00008 cs = 1; 00009 00010 // Setup the spi for 8 bit data, high steady state clock, 00011 // second edge capture, with a 1MHz clock rate 00012 spi.format(8,3); 00013 spi.frequency(1000000); 00014 00015 // Select the device by seting chip select low 00016 cs = 0; 00017 00018 // Send 0x8f, the command to read the WHOAMI register 00019 spi.write(0x8F); 00020 00021 // Send a dummy byte to receive the contents of the WHOAMI register 00022 int whoami = spi.write(0x00); 00023 printf("WHOAMI register = 0x%X\n", whoami); 00024 00025 // Deselect the device 00026 cs = 1; 00027 }
API¶
Import librarymbed
Interface¶
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| See the Pinout page for more details |
The default settings of the SPI interface are 1MHz, 8-bit, Mode 0
The SPI Interface can be used to write data words out of the SPI port, returning the data received back from the SPI slave. The SPI clock frequency and format can also be configured. The format is set to data word length 8 to 16 bits, and the mode as per the table below:
| Mode | Polarity | Phase |
|---|---|---|
| 0 | 0 | 0 |
| 1 | 0 | 1 |
| 2 | 1 | 0 |
| 3 | 1 | 1 |
The SPI master generates a clock to synchronously drive a serial bit stream slave. The slave returns a bit stream, also synchronous to the clock.