The use of Gpio_pinremapconfig functions in the STM32 library

Why is it impossible for beginners to control 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 a specified pin gpio_remap_swj_disable SWJ completely disabled (JTAG+SW-DP)
Gpio_pinremapconfig (gpio_remap_swj_jtagdisable, ENABLE);
Change the mapping of the specified pin gpio_remap_swj_jtagdisable, 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 Afio clock in rcc_configuration (),
Afio Clock
Rcc_apb2periphclockcmd (Rcc_apb2periph_afio, ENABLE);

The use of Gpio_pinremapconfig functions in the STM32 library