Experience of autumn recruitment in 22 years

1 Self introduction.

2 TP-LINK

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3 Haier Group

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6.13 Evaluation notice ： Evaluation is a general logical and psychological problem , No programming problem
6.30 one side ：10 minute water I turn on the camera , They don't drive
1、 Self introduction.
2、 What is the specific direction of graduate students now
answer ： New energy system integration and control
3、 Do you have any experience in power electronic conversion
4、 Graduate research topics
answer ： engineering 、 There are two aspects of scientific research
5、 Do you still want to do new energy in the future
6、 Which kinds of MCU are you familiar with ？
7、 Workplace
8、 Are you familiar with Qingdao
9、 We do air conditioning here , Do you have any requirements for product type ？

Approve ahead of time 6.23 Resumes GEDP- Embedded software direction
6.29 one side ： about 40 minute , A person HR, A technical HR
1、 Self introduction.
2、 Bao Yan or Kaoyan
3、 Where is home , Only Sichuan and Chongqing are considered when looking for a job ？ Or the whole country
4、 What do you value when looking for a job , It is the platform development of the company ？ Or industry , Or something else
5、 Many companies need embedded talents , Which small direction do you prefer in the embedded industry ？
6、 How about oral English
7、 Have you ever participated in some activities of clubs or schools
8、 Do you have any hobbies , Which extracurricular books do you like to read , Share a new knowledge learned recently through books
9、 Simply make a comment on yourself
10、 Do you have a girlfriend? . Girlfriend's plan
11、 Introduce to you bootloader Related functions
12、 The resume mentions buttons 、LCD、 Resistive touch screen , What are these achieved through ？
13、 Write personal self-study development , Is there a specific project or a simple personal hobby
14、48V What topology is mainly used in the project ？ It's a DCDC System ？ This DCDC It is made of pure analog circuit , No digital control ？
15、28335 This DSP What role does it play in the whole system ?
16、48V What kind of communication mode is used in the project ？ answer ：SPI. ask spi Corresponding communication protocol and communication format
17、28335 of use spi, Who to communicate with ？ Between boards ？ answer ： It mainly receives voltage and current data . ask ： Receiving data is not AD The function of the collector ？
answer ：AD Only data can be received , Cannot transmit data . ask ：AD Is it a separate chip ？ still 28335 It comes with ？ answer ： Used alone AD chip . ask ： This individual AD Have you known the relevant control code of sampling chip ？ answer ： see AD Chip manual , combination 28335 Manuals .
18、 You are the student who controls the direction , What control related algorithms are useful in your work ？
19、 What applications can you apply these knowledge in the field of home appliances ？
20、 Does your project need to build a system control model ? answer ： need , Build a block diagram , Transfer function
21、 How to judge the stability after getting the model , Introduce to you nyquist Stability criterion
22、 What is the content of your graduation thesis

4 Changjiang storage

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5 sanhuan

Approve ahead of time 6.14 Resumes Invested in direct evaluation （6min It's simple ）
6.30 one side ： Ask all 48V project 25min
1、 Self introduction.
3、 Whole 48V What are the components of the system
answer ：DSP、 Communications 、AD、DCDC
2、SPI and I2C The difference between
3、SPI What is the composition of a communication frame
4、AD What kind of voltage and current are sampled
5、 It is used alone AD Chip ？
6、AD What is the accuracy of ？ AD What is the voltage input range of ？
7、DSP How much is the chip power supply V Of ？
8、AD Is there any filtering in the sampling process ？
answer ：50 Sub average filtering ask ： Why choose 50 Time ？ answer ： Look at the display speed under different times
9、 The control of the whole system , Which are more interesting 、 The more difficult point 、 Bright spot
10、 How to judge the switching of power supply between lithium battery and fuel cell
11、48v What kind of collaboration is the project collaboration of
12、 If something is urgent , But for example, hardware makers are not free , What should I do
answer ： Ask them for advice , Ask the teacher , And Yan San
13、 Arrange a job for a classmate , He told you privately that he didn't want to do it , How to deal with

6 Huawei （ wireless 、2012）

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7 mediatek

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6.30 written examination ：

8 Zhongkexin

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9 Shaoyin Technology

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10 Dahua Co., Ltd

Approve ahead of time 6.18 Resumes Linux C Software engineer
6.27 written examination 30 Road single choice Fill in the blanks with a few lines Several algorithms altogether 37 Avenue , Half C Half C++, An hour , There is not enough time for the last two , Didn't do it
Knowledge points I am not familiar with ：
1、 Memory leaks , The following incorrect is ：
Process usage malloc perhaps new Application memory , There is no release , May cause memory leaks
Memory leaks continuously , May cause oom-killer abnormal
After the process exits , The leaked memory has not been released , The system cannot use these memories
Before allocating memory to a pointer , If not empty , May cause memory leaks
2、 What is right in the following statement is ：
Function definitions cannot be nested , But function calls can be nested
main Function must be placed before other functions
All called functions must be defined before calling ： This is not true , Define only once , Declare before each call
stay C All functions that have a calling relationship in a language program must be placed in the same source file
3、switch Usage of ：

void main(void)
{
    
    int sum = 0;
    for (int j = 1; j < 4; j++)
    {
    
        switch (j)
        {
    
        case(1):
            continue;
        case(2):
            sum += j;
            break;
        }
        sum += j;
    }
 printf("ans4 is %d\n", sum);
}

4、64 Bit operating system , Size of structure with bit field ：

 struct a
    {
    
        char t : 4;
        char k : 4;
        unsigned short i : 8;
        unsigned char* p;
        unsigned long m;
    };
    int ans = sizeof(struct a);

5、 Define a global variable ,static int a=0; be a In which area ？
stack;bas;bss;heap;

11 The 10th Research Institute of CETC

Approve ahead of time 6.21 Resumes Drive Engineer
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12 ZTE

Blue Sword project 6.22 Resumes Embedded software development
Future leadership plan 6.24 Resumes Embedded software development （ operating system ）

13 arcsoft

sp Special field 6.22 Resumes Embedded driver / software development

14 Ruijie network

Approve ahead of time 6.22 Resumes C/C++ Development Engineer
6.22 Evaluation ： For an hour , Line test plus Psychology , Many people have been tested
6.23 Received the written examination notice ： The written examination content is 50 Single to , More than 40 ways are pure C Language program , Several other miscellaneous . Main test points ： Macro expansion ,sizeof A structure , Precedence of various operators , The order in which expressions are evaluated , Evaluation order of assignment , Array name and array pointer , An operation ,
1、

int a[5]={
    15,14,13,12,11};
int * p;
p=a;
*(p++)+=10;
 ask ：*p,*(++p) Value 

2、

int a[10]={
    1,2,3,4,5,6,9,8};
int  p=(a+4)[2];
 ask ： p  Value 

answer ：9
3、 The average time complexity is zero o（nlogn） Sort algorithm
4、 An array a Pass in the function as an argument , The array name is passed , In the function sizeof(a), How much output ？
answer ： The array name passes in a pointer , Output is 4, If in the main function sizeof（ Array name ）, The output is the byte length of the array
5、

a=10,i=4;
a%=i+1;
 ask :a Value 

answer ：0,a%=i+1 be equal to a=a%(i+1);
6、

a=12;
a+=a-=a*=a&a;
 ask :a Value 

answer ：0, From right to left
7、 Define a pointer , Point to 3 That's ok 4 Column int Array

 answer ：int (*p) [3][4]

8、

char a=3,b=6,c;
c=a^b<<2;
 ask :c Value 

answer ：0x1b, Monocular priority is higher than binocular
9、10/3*3 Value
answer ：9, Same priority , The combination of arithmetic operations is left to right ;
10、 Which structure can realize the rapid retrieval and insertion of data ： Trees 、hash、 Linked list 、 Array
answer ：hash
11、 The data type of the operand on both sides of the logical operator
answer ： The data type of the operands on both sides of the logical operator can be any type of data . Because both sides of the logical operator are eventually converted to bool Value operation , therefore bool The value is only non-zero ( from 1 Express ) And zero , So as long as it is not zero , It will be converted into 1, Therefore, any value of any type can participate in the operation
12、

char a=48;
int c=sizeof(a*2);
 ask :c Value 
float b1 = 3.1;
double b2 = 3.14;
int c1 = sizeof(a*b1);
int c2 = sizeof(a*b2);

answer ：4, If it's simple sizeof(a), The answer is 1, Because I took 2,2 The default is int type , It is equivalent to improving the type ,a*2 Turned into int type ; Empathy c1 The value of is float Size , by 4,c2 The value of is double Size , by 8.
13、d by double type , expression d=1,d+5,d++ The final value
14、 One structure is put into int、double、float、char, Ask the size of the structure
15、 Advantages and disadvantages of micro kernel and macro kernel
16、

 Defining macro  ABS(X) (((X)<0 ? -(X)  :(X))
int m=-5;
ABS(++m) Value 

answer ：3.
17、

str="hello\n\0\n";
strlen(str); Value 

answer :6, First meet \0 You will think that the string ends , secondly \n Represents a character , Not two .
18、Linux Storage management technology actually used （ Pagination ）
19、

a=10;
b=a++;
c=++a;
d=10*a++
 ask d Value 

answer ：120
20、

int a[]={
    1,2,3,4,5,6};
int *p=&a[2];
 Output *(p-1),*(p),*(p+1),*(p+2);

answer ;2,3,4,5
21、

unsigned int a=1;
unsigned int b=2;
int ret1;
unsigned int ret2;
ret1=a-b;
ret2=a-b;
 ask ret1 and ret2 Value （32 Bit system ）

answer ;-1,-1
22、

int a[3][3],*p,i;
p=&a[0][0];
for(i=0;i<9;i++)
{
    
	p[i]=i+1;
}
 ask a[1][2] Value 

answer ：6, Don't understand,

6.30 one side ： 35 minute
1、 Self introduction.
2、boot loadder From power on , To load the operating system init Program , What kind of process is the whole process ？
answer ： From which storage medium , What program to choose （nor perhaps nand, link , Reposition these and spit them out ）, Startup file , The first instruction jumps to reset interrupt , Set stack in reset interrupt , Set always , Finally jump to main function , And then there was bootloader Of C Language link , Later on C Initialize hardware in language , Set the startup parameters of the operating system , Finally, jump to the operating system .
ask ： Have you studied this part in depth ？
answer ： Transplanted Uboot, A large file system , After in-depth understanding, many documents are different architectures , Migration is to modify the configuration file , I haven't seen the specific code inside ,start.S See more .
ask ： Transplant a system , Except transplantation BootLoader And beyond the kernel , There is nothing else ？
answer ： The operation of the program also needs to transplant the root file system ,busybox,inttab,0 Process of no. init process
ask ：uboot and bios What is the relationship between ？
answer ： It's basically the same kind of thing ,bios Running on the windows Next . HR Wrong answer , There is a difference between the two
3、 You think you are right TCP and UDP To what extent ？
answer ：TCP and UDP It is the protocol of data transmission in network programming , Why network programming （ Print error messages ）, It is essentially a process of data transmission , There are three elements of data transmission ,TCP and UDP In which position ,TCP and UDP The differences and application scenarios of ,TCP Specific application methods of （socket,bind, Such as function ）
4、 Have you ever studied the driver of network card ？
answer ： No research at all （ Be careful not to answer like this and it's over , Pull into your own field ）, Have studied character and block devices , Network driven is quite different from the former two , Continue to say that you have studied LCD And touch screen drive , Studied the drive framework
ask ： Tell me about a familiar driver , Start with the frame , Say what you think
answer ： Character driven , For example, keys , If you don't pursue generalization , direct writing file operation Just go , Implement some interrupts 、poll etc. , Pursue generalization , Plus the input subsystem framework
ask ： You know, platform What do you mean ？
answer ： Virtual platform bus , Derived from the bus device driver model , And its relationship with subsystem level
5、 Choose a project that you find interesting , Talk about three aspects of the project , First, what is the project （ General introduction ）, Two is , What did you do in the project , The third is what successful or unsuccessful experience you have gained from this project ？
ask ： You wrote LCD drive ,LCD What do you need to do in the driver ？（LCD How to drive with the help of framework , What do we need to accomplish under the framework ）
6、 What languages do you master or know
answer ：C C++ matlab makefile shell
ask ： You feel C What are the advantages of language ？
answer ： High level language closest to the bottom , No matter how low it is, it is difficult to describe a computer system completely , For example, assembly , Programming difficulties , No matter how high, there are all kinds of packages , I can't see the specific details
ask ： What kind of architecture assembly language have you learned
answer ：ARM
7、 stay linux What is the difference between processes and threads ？
answer ： Basically no difference ,linux There is no concept of a separate thread , Threads are lightweight processes , Different threads share something in a process （ There is a post about user threads and kernel threads , To have a look at , This explanation goes deeper ）
ask ： Just now we talked about the differences between threads and processes in Kernel Implementation , What is the difference between processes and threads on the external layer ？
answer ： Hierarchical differences , Large tasks use processes , Threads are used for small tasks in large tasks , Process switching costs more
ask ： Interaction between processes and communication between threads , Is there any difference ？
answer ： The consumption of process switching and thread switching is different （ I heard the wrong topic , I say switch , People ask about process thread communication ）
ask ： Have you written any programs that work together between processes or threads
answer ： nothing , Read a lot of books , But it hasn't been implemented yet , For example, I have seen the introduction to the operating system （ Trying to get him to ask me about the octet of the operating system , Sure enough, I asked later ）
ask ： Many books believe that operating systems are mainly virtualization , Which virtualization ？
answer ：CPU virtualization , Memory virtualization
ask ： How do you understand segmentation and paging ？
answer ： Just spit it out after the vein on the book

15 The 23rd Institute of the second Academy of Aerospace Science and industry of China Chengdu R & D center

Approve ahead of time 6.23 Email resume

16 Qingdao Dingxin Communication Co., Ltd

Approve ahead of time 6.23 Resumes Embedded Development Engineer

7.4 one side ： Neither side turned on the camera 25 min
1、 Self introduction.
2、 Look at your resume , be familiar with linux operating system , Yes linux+ARM Development experience , Your development experience refers to kernel driver or application ？
answer ： Kernel driver
3、Linux Start process , From power on , To kernel , Load to system
answer ：BootLoader To kernel The root file system init process inittab（ I feel that he thinks my answer is relatively brief ）
experience ： This question has been asked many times , Go and analyze it in detail . Ask this question again next time , First ask him whether he wants to hear detailed or general , Prepare both
4、 understand GRUB Do you ？
answer ： Don't understand （ Baidu , yes GNU Start up procedures for multiple operating systems , In it, you can configure which operating system you want to start , I don't involve multiple operating systems ）
5、Linux Of run level There are several levels ？
answer ： I do not know!
6、 that system D Do you understand? ？
answer ： I don't know
experience ： This HR It's on the server Linux C Of , The questions I ask are all my knowledge blind spots
7、init Do you know the process
answer ： Whole linux The process in which the system first runs , Everything to be done inside is based on inittab To run
8、Linux What are the advantages of intrusive linked lists in the kernel over ordinary linked lists ？
answer ： I have no idea
9、 See you understand the basic data structure and Algorithm , How to calculate the time and space complexity of an algorithm , Like bubble sort
answer ： For bubble sorting Time is complicated O(n), Because it has two for loop , Space complexity O(1), Because it doesn't involve extra space .
10、 Look at your resume and say you understand C++ Language , Do you know more about it ？
answer ： For undergraduate C++ Played a game , Now I forgot the grammar of the specific details , know C++ and C The difference between .HR say , In that case, don't ask C++ 了 ？（ I answered thank you, teacher , Or he should ask ？ Just say that you don't just know what you need to make up ）
experience ： Or don't write it on your resume C++ 了 ？
11、 See what you mainly do Linux, Have you ever done ordinary single chip computers ？
answer ： Undergraduate course design , match , Graduate engineering project
12、 How did you think of coming to Shandong to find a job ？
13、 What is the direction of your paper ？
answer ： New energy system integration and control 、matlab Simulation 、 Experimental research 、 The two reflect each other
14、 Your thesis is 48V UAV project
answer ： The project is engineering , The battery used in the project is the battery in the paper
15、 How heavy is your whole plane , How many batteries , How big ？ Is it a fixed wing or a multi rotor aircraft ？ How long can it last ？ How long can an ordinary lithium battery UAV last ？
16、 Do you think this fuel cell UAV has the prospect of mass production ？
answer ： There is a prospect , There are also several constraints , For example, hydrogen cylinders 、 All kinds of environments 、 Manufacturing cost
17、 What is your main job in this project ？ Simulation 、 verification ？
answer ： Simulation verification 、 Programming 、 management
experience ： It seems that they are very interested in the fuel cell project in the medium term , I don't know if the picture is the reason why I didn't answer well before , I didn't even ask , Do I need to write the project of the picture in more detail .
18、 I think your resume has multi process and multi thread program architecture , Can you tell me how you use multi process and multi thread architecture to realize your project functions ?
answer ： Picture view , Move left, move right .
19、 Which method is used for inter thread communication ？
answer ： Synchronous signal
20、 It's just that this thread notifies another thread ？ Including data interaction between threads ？
answer ： barring , Just a simple notice “ I'm ready ” This signal .
21、 How to understand the concept of process and thread ？（zwg： This question can be answered in detail , You can also briefly say ）
answer ： For other modern operating systems , about Linux operating system .
22、 establish thread, my thread It can be separated or not , I built this thread Is it a process or a thread ？
answer ： Basically not
23、 You have some common buses , For example, serial port 、SPI、I2C, You are familiar with how to use it ？ Or are you familiar with their principles ？
answer ： Both are involved , How to use it is just two manuals , register , The principle is the manual of specific chips , sequential
24、 I asked ： Your company hires embedded software engineers , About what to do ？
answer ： Mainly STM32 Single board products , Also have Linux The server , Write on it C Program .

16 Shenzhen Yuanrong set sail

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17 Changsha Beiyun Technology

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18 Shanghai Hesai Technology

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19 CLP 29 the

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20 Shanghai Anlu Technology Co., Ltd

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21 Hexin Starcom

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22 glory

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23 Zheku Technology

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23 Lexin technology

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24 oppo

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25 Scripture is always moist

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26 Wanji technology

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27 Fengfei Technology

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28 Dajiang

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29 Sino Singapore SECCO

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30 Guodian south from

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