About STM32 PB3 PB4 How to set up a general Gpio configuration

For beginners, why not control the output when using PB3 and PB4.

The following is an analysis of this issue.

First, after the STM32F10X series MCU is reset, the PA13/14/15 & PB3/4 is configured as a JTAG feature by default. Sometimes in order to make full use of the resources of the MCU I/O port, these
The port is set to a normal I/O port. Here's how:
In Gpio_configuration (); Configure the GPIO ports used:

Gpio_pinremapconfig (gpio_remap_swj_disable, ENABLE);
//change the mapping of the specified pin gpio_remap_swj_disable SWJ completely disabled (jtag+ SW-DP)
Gpio_pinremapconfig (gpio_remap_swj_jtagdisable, ENABLE);
//change the mapping gpio_remap_swj_jtagdisable of the specified PIN, JTAG-DP Disable + SW-DP enable

  gpio_initstructure.gpio_pin = Gpio_pin_3 | Gpio_pin_4;
  gpio_initstructure.gpio_speed = Gpio_speed_50mhz;
  gpio_initstructure.gpio_mode = gpio_mode_out_pp;
  gpio_init (GPIOB, &gpio_initstructure);

  gpio_initstructure.gpio_pin = Gpio_pin_11 | Gpio_pin_12 | gpio_pin_13;
  gpio_initstructure.gpio_speed = Gpio_speed_50mhz;
  gpio_initstructure.gpio_mode = gpio_mode_out_pp;
  gpio_init (Gpioa, &gpio_initstructure);  

Note: Do not forget to turn on the rcc_configuration clock in Afio (),
  //afio Clock
rcc_apb2periphclockcmd (Rcc_apb2periph_afio, ENABLE);