Blue Bridge Cup embedded Hal library systick

The experiment purpose

Through the tick timer to achieve one-way flow lamp effect

Hardware design

PC8~PC15 Corresponding G4 On board LED Of a lamp LD1~LD8
PD2 Connect latch
explain ： According to the schematic diagram ,LED Light in Low level when bright , High level when destroy
The enable end of the latch is connected with PD2 Connected to a , Latch data at low level （ The latch output does not vary with the input ）, Data is not latched at high power （ The latch output varies with the input ）

unsigned char

1、unsigned char Is an unsigned byte type ,char The size of type variables is usually 1 Bytes （1 byte =8 bits ）, And it belongs to integer .

2、 stay 32 One of the bit systems char The type is generally 8 individual bit, Therefore, the range of data that can be stored is -128~127, and unsigned char It is 0~255, The data stored in character type is used to represent characters , for example ASCⅡ or Unicode.

link ：unsigned char

unsigned char summary

unsigned char The range that can be expressed is 0~255, therefore unsigned char ms_led =1000 Out of range , There will be a warning .

processing method

Defined as unsigned int ms_led =1000

remaining problems

1、 How to make the direction of the water lamp from LD8 To LD1？？
2、ms_led=0;// Why does removing this sentence also have the effect of running water lamp , But the time of running water lamp slows down ？

Summary of the experiment

adopt SYSTICK Interrupt the service function to realize the running light effect ,1ms Enter an interrupt service function .
The key code to realize the water lamp ：GPIOC->ODR=~(0x0001 << ++i).
Variable i Auxiliary shift , Variable ms_led Auxiliary delay .
PD2 Used to latch data .

Blue Bridge Cup -HAL library -USART_TX