Contents
Where can I find the C code for SPI?
The C-Code below is also available in the following files: spi.c and MAX7456.h The code uses the standard nomenclature for the SPI lines. The MAXQ2000 processor is the SPI master and the MAX7456 is the SPI slave. CS is the same as is used in the MAX7456 data sheet.
Can a SPI interface have more than one slave?
SPI devices support much higher clock frequencies compared to I 2 C interfaces. Users should consult the product data sheet for the clock frequency specification of the SPI interface. SPI interfaces can have only one master and can have one or multiple slaves. Figure 1 shows the SPI connection between the master and the slave.
What’s the difference between chip select and SPI?
Usually chip select is an active low signal; hence, the master must send a logic 0 on this signal to select the slave. SPI is a full-duplex interface; both master and slave can send data at the same time via the MOSI and MISO lines respectively.
How does the SPI interface work on a clock?
The SPI interface provides the user with flexibility to select the rising or falling edge of the clock to sample and/or shift the data. Please refer to the device data sheet to determine the number of data bits transmitted using the SPI interface. In SPI, the master can select the clock polarity and clock phase.
What is the read capability of the SPI interface?
The SPI-compatible serial interface programs the operating modes, the display memory, and the character memory. Read capability permits both write verification and reading of the Status (STAT), Display Memory Data Out (DMDO), and Character Memory Data Out (CMDO) registers.
How are two loops used in SPI routine?
If one can guarantee that the active-low CS and CK lines are at the correct state on entry, the first two instructions can be removed. The routine first sends the address followed by the data. Two loops are used for this. It is possible to simplify the routine by using a single loop and a 16-bit data store.
What’s the difference between sdout, SCLK and SPI?
SDOUT is referred to as MOSI (master in slave out). SCLK is referred to as CK. The prefix SPI_ is used on all lines. The data structure shown below is used to access data directly or bit by bit. This is used to access the pins for the SPI port individually.