51 can the single chip microcomputer make the LED light into a breathing light, how to delay, how mu

Use a single-chip microcomputer that replaces PWM, just use a loop, while(1).

num++;Assign this number to the PWM counter.

delay();The length of breathing time adjusts this delay function.

Yes, use the PWM duty cycle to do it, and the resources on 51 can do several groups.

The cost of DA is too high. It is cheap with PWM** and has a simple circuit. The estimation frequency must be in the kilohertz, 51 may be a little more difficult.

The brightness should also be controlled, and there should be da control.

#define p_ioa_data (volatile unsigned int *)0x7000

#define p_ioa_dir (volatile unsigned int *)0x7002

#define p_ioa_attrib (volatile unsigned int *)0x7003

unsigned int scan();Detect black line function definite declaration unsigned int num=0;

void delay();

void init 1() input initialization.

void init 2() output initializes void main().

case 2:

case 4:

case 5:

case 0:}}

p_ioa_data]=0x5f;Straight Delay(500); }

void delay(uint z)

unsigned int scan()

if(line_2==0xfd)

if(line_4==0xfb)

if(line_5==0xf7)

return 0;}

org 0000h

ljmp 0100h

org 0100h

main: clr ；LED1 is lit.

lcall ys5m ；Delay 5 seconds setb; led1 off sjmp$

ys5m: mov r7,#100 ；Delay 5 seconds.

yll1: mov r6,#200yll2: mov r5,#123yll3:

djnz r5,yll3djnz r6,yll2

djnz r7,yll1ret

Likewise, you're going to ask c.

int main(void)

Note that the MCU program is executed from the main function, note that the main function of the single-chip microcomputer does not add a while loop, the program will be executed all the way down until the RAM overflow produces an error, and the program will run away, so the main program must increase the loop inside, and the above format is verified by countless engineers, the writing format of the main function.

You really should learn C a little bit, these are the more basic knowledge:

int main, is the main function, there is a return value, the main function is the entrance of the program, void main is the same, but the return value is not required, you can also use return in the main function; Empty statements.

Without the foundation of C language, you can't play single-chip microcomputer!!

You should learn C first.

1. Removing two delays at the same time will cause the level of the LED pins to continue to change between , the frequency of change is very fast, in the order of MHz, the result is that the light can not be seen directly, if the initial state of the light is off, the light will basically not see the brightness.

2. See the previous article, no flashing.

3. Remove the first delay, the actual lamp will continue to show the state of led=1 instruction, which is related to whether the control end of the LED lamp in the hardware is connected to the cathode or anode; Similarly, removing the second delay, the actual light will continue to exhibit the LED=1 command.

4. The fastest flashing of the lamp that the human eye can distinguish should be about tens of Hz, and the value of the delay function can be actually changed for testing; The slowest blinking speed depends on the longest delay time of delay, where the delay parameter num is 16 bits, then when num is taken as 65535, the lamp flashes the slowest bit, in addition, you can also increase the value of the internal parameter "y=110" of the delay function to increase the delay time and reduce the blinking speed.

If the output low level light is on, remove the first one or both and the light will not look on, and remove the second one and the light will look solid.

The button is detected with io, and it is best to add a button to deshake, delay the timer directly, or wait with for, and the eight diodes are also directly used with the io port.

Take turns with the value of the io port, one if to detect and one for to give the value.