Spyros Papanastasiou / Mbed 2 deprecated Write_to_port_directly__LED

Example program for Port access. Blink the LED using the registers.

Dependencies:   mbed

main.cpp@2:f72c56822d58, 2019-07-22 (annotated)

Committer:
Ladon
Date:
Mon Jul 22 13:44:32 2019 +0000
Revision:
2:f72c56822d58
Parent:
1:65c259961c26 
Replaced #defines with reinterpret_cast.

Who changed what in which revision?

UserRevisionLine numberNew contents of line
Ladon 0:e637d54ba0a3 1 #include <mbed.h>
Ladon 0:e637d54ba0a3 2
Ladon 1:65c259961c26 3 // Board: NUCLEO-F303RE (STM32F303RE).
Ladon 0:e637d54ba0a3 4 // -
Ladon 0:e637d54ba0a3 5
Ladon 0:e637d54ba0a3 6 // We shall write to PA5 where the LED is..
Ladon 0:e637d54ba0a3 7 // Info: LEDs:
Ladon 0:e637d54ba0a3 8 // https://www.st.com/resource/en/user_manual/dm00105823.pdf (UM1724: STM32 Nucleo-64 boards (MB1136))
Ladon 1:65c259961c26 9 //
Ladon 0:e637d54ba0a3 10 // Info: Talking to ports:
Ladon 0:e637d54ba0a3 11 // https://developer.arm.com/tools-and-software/embedded/legacy-tools/ds-5-development-studio/resources/tutorials/accessing-memory-mapped-peripherals
Ladon 1:65c259961c26 12 // More info: Chapter 25.4.1 from "2014 Programming Principles and Practice Using C++"
Ladon 1:65c259961c26 13 /// (https://archive.org/details/2014ProgrammingPrinciplesAndPracticeUsingCPlusPlus/page/n636)
Ladon 1:65c259961c26 14 //
Ladon 0:e637d54ba0a3 15 // Info: #defines :
Ladon 0:e637d54ba0a3 16 // https://raw.githubusercontent.com/ARMmbed/mbed-os/master/targets/TARGET_STM/TARGET_STM32F3/TARGET_STM32F303xE/device/stm32f303xe.h
Ladon 1:65c259961c26 17 //
Ladon 0:e637d54ba0a3 18 // Reference manual:
Ladon 0:e637d54ba0a3 19 // https://www.st.com/resource/en/reference_manual/dm00043574.pdf
Ladon 0:e637d54ba0a3 20 // -
Ladon 0:e637d54ba0a3 21 // We 'll need the MODER (port mode) register (see ^reference manual) and the ODR (output data register).
Ladon 0:e637d54ba0a3 22 // Register addresses are calculated taking the GPIOA base address (found in the reference manual) and adding the appropriate register's offset to it.
Ladon 0:e637d54ba0a3 23 // -
Ladon 0:e637d54ba0a3 24 // Note:
Ladon 0:e637d54ba0a3 25 // I was unsuccessfull in the following:
Ladon 0:e637d54ba0a3 26 //
Ladon 0:e637d54ba0a3 27 // #define ODR ((volatile unsigned short*) (GPIOA + 0x14)
Ladon 0:e637d54ba0a3 28 // -
Ladon 0:e637d54ba0a3 29
Ladon 2:f72c56822d58 30 // #define MODER ((volatile unsigned int*) 0x48000000U)
Ladon 2:f72c56822d58 31 volatile unsigned int* moder = reinterpret_cast<volatile unsigned int*>( 0x48000000U);
Ladon 0:e637d54ba0a3 32 // 32 bits.
Ladon 0:e637d54ba0a3 33 // We 'll set pins 11,10 set to 0,1.
Ladon 0:e637d54ba0a3 34 // -
Ladon 0:e637d54ba0a3 35
Ladon 2:f72c56822d58 36 // #define ODR ((volatile unsigned short*) 0x48000014U)
Ladon 2:f72c56822d58 37 volatile unsigned short* odr = reinterpret_cast<volatile unsigned short*>(0x48000014U);
Ladon 0:e637d54ba0a3 38 // 16 bits.
Ladon 0:e637d54ba0a3 39 // We 'll write at pin 5.
Ladon 0:e637d54ba0a3 40 // -
Ladon 0:e637d54ba0a3 41
Ladon 0:e637d54ba0a3 42 // More FUN (dwarf fortress reference).
Ladon 0:e637d54ba0a3 43 // -
Ladon 2:f72c56822d58 44 // #define OTYPER ((volatile unsigned short*) (0x48000004U))
Ladon 2:f72c56822d58 45 // #define PUPDR ((volatile unsigned int*) (0x4800000CU))
Ladon 2:f72c56822d58 46 // #define BSRR ((volatile unsigned int*) (0x48000018U))
Ladon 2:f72c56822d58 47 // #define LCKR ((volatile unsigned int*) (0x4800001CU))
Ladon 2:f72c56822d58 48 // #define AFRL ((volatile unsigned int*) (0x48000020U))
Ladon 2:f72c56822d58 49 volatile unsigned short* otyper = reinterpret_cast<volatile unsigned short*>(0x48000004U);
Ladon 2:f72c56822d58 50 volatile unsigned int* pupdr = reinterpret_cast<volatile unsigned int*>( 0x4800000CU);
Ladon 2:f72c56822d58 51 volatile unsigned int* bsrr = reinterpret_cast<volatile unsigned int*>( 0x48000018U);
Ladon 2:f72c56822d58 52 volatile unsigned int* lckr = reinterpret_cast<volatile unsigned int*>( 0x4800001CU);
Ladon 2:f72c56822d58 53 volatile unsigned int* afrl = reinterpret_cast<volatile unsigned int*>( 0x48000020U);
Ladon 0:e637d54ba0a3 54
Ladon 0:e637d54ba0a3 55 void set_bit_as_output ()
Ladon 0:e637d54ba0a3 56 {
Ladon 0:e637d54ba0a3 57 // Set to output.
Ladon 0:e637d54ba0a3 58 // -
Ladon 2:f72c56822d58 59 unsigned int tmp = *moder;
Ladon 2:f72c56822d58 60 tmp |= 0x00000400U;
Ladon 2:f72c56822d58 61 tmp &= 0xFFFFF7FFU;
Ladon 0:e637d54ba0a3 62 // ^ Write 0,1 to bits 11,10.
Ladon 0:e637d54ba0a3 63 // -
Ladon 2:f72c56822d58 64 *moder = tmp;
Ladon 0:e637d54ba0a3 65 }
Ladon 0:e637d54ba0a3 66
Ladon 0:e637d54ba0a3 67 void toggle_bit ()
Ladon 0:e637d54ba0a3 68 {
Ladon 0:e637d54ba0a3 69 ///*
Ladon 2:f72c56822d58 70 *odr ^= 0x20;
Ladon 0:e637d54ba0a3 71 //*/
Ladon 0:e637d54ba0a3 72 /*
Ladon 0:e637d54ba0a3 73 static bool state = false;
Ladon 0:e637d54ba0a3 74 if (state)
Ladon 0:e637d54ba0a3 75 {
Ladon 2:f72c56822d58 76 *bsrr = 0x00200000U;
Ladon 0:e637d54ba0a3 77 }
Ladon 0:e637d54ba0a3 78 else
Ladon 0:e637d54ba0a3 79 {
Ladon 2:f72c56822d58 80 *bsrr = 0x00000020U;
Ladon 0:e637d54ba0a3 81 }
Ladon 0:e637d54ba0a3 82 state = !state;
Ladon 0:e637d54ba0a3 83 */
Ladon 0:e637d54ba0a3 84 }
Ladon 0:e637d54ba0a3 85
Ladon 0:e637d54ba0a3 86 int main ()
Ladon 0:e637d54ba0a3 87 {
Ladon 0:e637d54ba0a3 88 set_bit_as_output();
Ladon 0:e637d54ba0a3 89 while (true)
Ladon 0:e637d54ba0a3 90 {
Ladon 0:e637d54ba0a3 91 toggle_bit();
Ladon 0:e637d54ba0a3 92 /*
Ladon 2:f72c56822d58 93 printf("MODER = 0x%X\n", *moder);
Ladon 2:f72c56822d58 94 printf("OTYPER = 0x%X\n", *otyper);
Ladon 2:f72c56822d58 95 printf("PUPDR = 0x%X\n", *pupdr);
Ladon 2:f72c56822d58 96 printf("ODR = 0x%hX\n", *odr);
Ladon 2:f72c56822d58 97 printf("LCKR = 0x%X\n", *lckr);
Ladon 2:f72c56822d58 98 printf("AFRL = 0x%X\n", *afrl);
Ladon 0:e637d54ba0a3 99 printf("\n");
Ladon 0:e637d54ba0a3 100 */
Ladon 0:e637d54ba0a3 101 wait(0.65);
Ladon 0:e637d54ba0a3 102 // ^ : https://os.mbed.com/docs/mbed-os/v5.13/apis/wait.html
Ladon 0:e637d54ba0a3 103 // -
Ladon 0:e637d54ba0a3 104 }
Ladon 0:e637d54ba0a3 105 }