SPI_Demo.cpp

Write "Hello world!" out via SPI protocol and receive an echo

cmake_minimum_required(VERSION 3.12)
find_package(PropWare REQUIRED)
 
project(SPI_Demo)
 
create_simple_executable(${PROJECT_NAME} SPI_Demo.cpp)

 
// Includes
#include <PropWare/PropWare.h>
#include <PropWare/gpio/simpleport.h>
#include <PropWare/serial/spi/spi.h>
 
using PropWare::Port;
using PropWare::SPI;
using PropWare::Pin;
using PropWare::SimplePort;
 
static const Port::Mask MOSI = Port::Mask::P0;
static const Port::Mask MISO = Port::Mask::P1;
static const Port::Mask SCLK = Port::Mask::P2;
static const Port::Mask CS   = Port::Mask::P6;
 
static const uint32_t               FREQ    = 100000;
static const SPI::Mode    MODE    = SPI::Mode::MODE_0;
static const SPI::BitMode BITMODE = SPI::BitMode::MSB_FIRST;
 
int main () {
    char string[] = "Hello world!\n";  // Create the test string
    char *s;    // Create a pointer variable that can be incremented in a loop
    char in;    // Create an input variable to store received values from SPI
    SPI spi = SPI::get_instance();
 
    // Initialize SPI module, giving it pin masks for the physical pins,
    // frequency for the clock, mode of SPI, and bitmode
    spi.set_mosi(MOSI);
    spi.set_miso(MISO);
    spi.set_sclk(SCLK);
    spi.set_clock(FREQ);
    spi.set_mode(MODE);
    spi.set_bit_mode(BITMODE);
 
    // Set chip select as an output (Note: the SPI module does not control chip
    // select)
    Pin cs(CS, Pin::Dir::OUT);
 
    SimplePort debugLEDs(Port::P16, 8, Pin::Dir::OUT);
 
    while (1) {
        s = string;         // Set the pointer to the beginning of the string
        while (*s) {        // Loop until we read the null-terminator
 
            waitcnt(CLKFREQ/100 + CNT);
 
            cs.clear();  // Enable the SPI slave attached to CS
            spi.shift_out(8, (uint32_t) *s);  // Output the next character of the string
 
            cs.set();
 
            waitcnt(CLKFREQ/100 + CNT);
            in = (char) 0xff;              // Reset input variable
            while (in != *s) {
                cs.clear();
                in = (char) spi.shift_in(8);  // Read in a value from the SPI device
                cs.set();
            }
 
            // Increment the character pointer
            ++s;
 
            // Print the character to the screen
            pwOut.put_char(in);
        }
 
        // Signal that the entire string has been sent
        debugLEDs.toggle();
    }
}