Theremin device.

[AlexJenjer]

Used hoverboard-firmware-hack-FOC. In complete delight. Thanks to the author.
I wanted to have fun with the side boards of the hoverboard. Create a theremin device.
When the board is tilted, it emits a sound of varying frequency.
Instead of LED1, I connected a speaker.
Using the STM32 ST-LINK Utility program, change Option Bytes Protection - Disabled, apply,
then check the box WDG_SW, apply.
The programmer gives errors, but changes the settings.
Download the program from ARM Keil v5.37
Create project, change compiler options c90 to gnu90 , No Warning
Debug Use options: ST-Link Debugger

file config.h
#define VARIANT_HOVERBOARD

file systick.c
// if (SysTick_Config(SystemCoreClock / 1000)){
if (SysTick_Config(SystemCoreClock / 200000)){

file mpu6050.c
// delay_ms(100);
delay_ms(20000);

file gd32f1x0_it.c
void SysTick_Handler(void)
{
tick_count_increment();
delay_decrement();
sound();
}

file util.c
extern MPU_Data mpu;
volatile int32_t x,x1;
void sound2(void) {
mpu_get_data(); x= mpu.euler.pitch >>2; if (x>1000) x=1000;
}
void sound(void) {
x1--; if (x1<1) {x1=x; toggle_led(LED1_GPIO_Port, LED1_Pin);}
}

file main.c
while(1) {
delay_1ms(100);
sound2();

// delay_1ms(DELAY_IN_MAIN_LOOP);

// handle_mpu6050();
// handle_sensors();
// handle_usart();
// handle_leds();
// main_loop_counter++;

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Alternatively, you can compile with gcc-arm-none-eabi,
then rename the output file from proj.elf to proj.axf
and substitute in ARM Keil. And from it to load into the controller.