STM3F4 Discovery notes

use CoIDE (CooCox) ready to use and no hustle to setup and install gcc ARM

_________________________GPIO_______________________________

there are A,B,C,D,E,F, I ports each port has 16 bit  and each has a set of registers :

 - 4 config regs
 - 2 Data regs
 - 1 Set_Reset reg
 - 1 Locking reg
 - 2 Alternative function regs

1-Config regs : 

*GPIOx_MODER:  32bit , 2 bits for each pin  00 input/ 01 output/ 10 alter func/ 11 analog.
*GPIOx_OTYPER: 32bit , 1bit per pin (0 -15 ) 0 push-pull output / 1  open drain .
*GPIOx_OSPEEDR: 32bit , 2bits for each pin 00 2MHZ / 01 25MHZ / 10 50MHZ / 11 100-80MHZ.
*GPIOx_PUPDR: 32bit , 2 bit for each pin     00 N pull-push / 01 pullup / 10 pushdown /11 reserved

2-Data regs :

*GPIOx_IDR : 32bit , only 0-15 used
*GPIOx_ODR: 32bit , only 0-15 used

 3-Set/Reset reg:

*GPIOx_BSRR : 32  bit write only.    0-15 set reg    16-31   reset reg (manupilates ODR )

4-Lock reg:

*GPIOx_LCKR: 32 bit only 0-16 used.  0-15 port config lock ,  16 lock on/off  (has special sequence to enable )

5-Alternative functions reg:

*GPIOx_AFRH: 32 bit
*GPIOx_AFRL: 32 bit


all the reg's naming is defined under the ST library : "stm32f4xx.h" and "stm32f4xx_gpio.h"
you access the regs as follows : GPIOx->MODER

to config pins

GPIO_InitTypeDef GPIO_InitStructure;                                                          //structure to hold the configs

RCC_AHB1PeriphClockCmd(RCC_AHB1Periph_GPIOD, ENABLE);        // enable the clock

GPIO_InitStructure.GPIO_Pin = GPIO_Pin_11 | GPIO_Pin_12;                    // select the pins

GPIO_InitStructure.GPIO_Mode = GPIO_Mode_OUT;                                 // set the mode  in out ana alt

GPIO_InitStructure.GPIO_OType = GPIO_OType_PP;                                 //  set the type pp od

GPIO_InitStructure.GPIO_Speed = GPIO_Speed_100MHz;                          // set the speed

GPIO_InitStructure.GPIO_PuPd = GPIO_PuPd_NOPULL;                            // set pu pd resistors

GPIO_Init(GPIOD, &GPIO_InitStructure);                                                      // apply the structure to the desired port  & is used to keep other configs (no overwriting )

for manipulating the pins

GPIO_SetBits(GPIOD, GPIO_Pin_5);

GPIO_ResetBits(GPIOD, GPIO_Pin_12|GPIO_Pin_13|GPIO_Pin_14|GPIO_Pin_15 | GPIO_Pin_5);

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this is collected from blogs and official ST  docs

patrick leyman blog
STM32F4 docs