Part 14 - double

Today we are going to handle the double data type. As we discussed, in the Pico there is no co-processor to handle floating-point numbers as this is handled through a series of functionality through software in the API. This is the same with double-precision.

Let's work with a simple example. 0x06_double.c as follows.

#include <stdio.h>
#include "pico/stdlib.h"

int main() 
{
  stdio_init_all();

  while(1) 
  {
    double x = 40.5;

    printf("%f\n", x); 

    sleep_ms(1000);
  }

  return 0;
}

Very simply we assign a float of 40.5 into x and print it with the %f _format modifier and then sleep for _1 second.

Let's make a new dir 0x06_double and add our CMakeLists.txt file in it.

cmake_minimum_required(VERSION 3.13)

include(pico_sdk_import.cmake)

project(test_project C CXX ASM)
set(CMAKE_C_STANDARD 11) 
set(CMAKE_CXX_STANDARD 17) 
pico_sdk_init()

add_executable(0x06_double
  0x06_double.c
)

pico_enable_stdio_usb(0x06_double 1)

pico_add_extra_outputs(0x056_double)

target_link_libraries(0x06_double pico_stdlib)

Next we need to copy the pico_sdk_import.cmake file from the external folder in the pico-sdk installation to the 0x06_double project folder.

cp ../pico-sdk/external/pico_sdk_import.cmake .

Finally we are ready to build.

mkdir build
cd build
export PICO_SDK_PATH=../../pico-sdk
cmake ..
make

Then simply copy the .uf2 file to the drive.

cp 0x06_double.uf2 /Volumes/RPI-RP2

Then we need to locate the USB drive so you can do the following.

ls /dev/tty.

Press tab to find the drive and then in my case I will use screen to connect.

screen /dev/tty.usbmodem0000000000001

You should see a an 40.5 being printed every second.

In our next lesson we will debug.

Part 14 - double

Part 14 - double

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