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Hello, I have developed an application using the 8051 and c51, there is a external memory 93c46 which contains the control variables for the applcations, these variables are read at the start of the application and are used further in the application. The values read from the memory are stored in the global variables and are used in the different routiens for the control purpose These variable get corrupted in the middle of the application causing unpridictable results. How can i say these variable get Corrupted? There is a ruotien to update these variables. The value of variables are displayed on screen and can be changed, after all the values are scaned and the values are stored back in the memory and application runs with the updated variables. so if a variable gets corupted it is visible in the routien which updates these variables More over if we switch off the application after seeing the corrupted variables in the the updation routien, before saving the corrupted variables, then after switching on the variables are read from the external memory perfectely well and can be seen quite well in the updation routien I am using AT89c51 micro which means the global variables get corrupted, which gets displayed in the updation rouotien Any help will be highly appericiated Thanks in advance Kapil
I have seen such things happen only when an interrupt happened while 7 lines of code in main were executed and other such cases. Erik could very well be right about your problem here. He might be suggesting that you have a "race condition." In general, it is dangerous to use a variable in both main code and an interrupt, unless all the actions on it can be "atomic" (completed in one assembly instruction that is not interruptible). For instance, imagine you had the following:
unsigned int baduse; void sometimerint(void) interrupt X { baduse = baduse + someoffset; } void main(void) { while(1) { delay(sometime); printf("%i",baduse); baduse++; } }
The variable which gets corrupted are not at all used in the interrupt(timer interrupt)service routien Which 7 lines of code while being executed can cause this problem? and WHY? is this a compiler bug or what? About stack overflow i dont know? i will check. the major problem on my end is that i dont have an emulator and i havent seen this problem on the simulator. i am trying to see it I see it only when the application runs
The variable which gets corrupted are not at all used in the interrupt(timer interrupt)service routien That is totally irrelevant Which 7 lines of code while being executed can cause this problem? and WHY? is this a compiler bug or what? 7 lines in a program I fixed and NO it is not a compiler bug, it was missing stack control. About stack overflow i dont know? i will check. the major problem on my end is that i dont have an emulator and i havent seen this problem on the simulator. i am trying to see it set a breakpoint in the simulator at the deepest subroutine level you have. check SP. then set the bit that activates your heaviest interrupt and let it enter, then check sp. I think this might work as a check using the ineffective method of simulating. Erik
Jay when i see this problem it happens to the first 2 varibles i mean if we have 10 variables of type unsigned int (starting address of first variable is 0x28 in ram and all athe variables are placed one after other)then first 2 gets corrupted everytime
I have just checked the stack values when the programe runs but the stack is placed at 0x58 and maximum it goes up to 0x62 but the varibles which gets corrupted are placed at 0x2B to 0x2E
Can you post the smallest complete compilable program that shows the problem. Please cut and paste this from your editor to ensure that the code you post is exactly the same as the code you are using.
This is interrupt file /* ADC.C */ #include <reg51.h> #define HIGH 1 #define LOW 0 #define ON 1 #define OFF 0 extern unsigned char Nibble[5]; extern unsigned char nibble_reference; sbit Mode_sw = 0xB7; sbit Down_sw = 0xB7; sbit Up_sw = 0xB6; sbit STOP_sw = 0xB6; sbit D5 = 0x94; sfr In_Data = 0x90; extern unsigned int COUNTER; unsigned char Temp_Counter=0; unsigned char Temp_Counter1=0; extern bit STOP_SW_bit ; extern bit Screen_Flag ; void Enable_Interrupts(){ // Enable the Timer/Counter 0 Interrupt No 1 TR0 = 0; TMOD &= ~0x0F; /* clear timer 0 mode bits */ TMOD |= 0x01; /* put timer 0 into 16-bit no prescale */ TL0 = 00; TH0 = 200; PT0 = 0; /* set low priority for timer 0 */ ET0 = 1; /* enable timer 0 interrupt */ TR0 = 1; /* start timer 0 */ // Enable the Timer/Counter 1 Interrupt No 4 // Enable the External 0 Interrupt No 0 // Enable the External 1 Interrupt No 2 EX1 = 1; // Enable the SCI Interrupt No 5 // Enable Global EA = 1; } External_1() interrupt 2 using 3 { if(D5) nibble_reference = 0; // this is the starting, MSB is sent after this Nibble[nibble_reference] = In_Data; Nibble[nibble_reference] &= 0x0F; ++nibble_reference; } Timer0 () interrupt 1 using 2 { TL0 = 55; TH0 = 248; Temp_Counter++; if(Temp_Counter >= 100){ Temp_Counter =0; Temp_Counter1++; COUNTER++; } }
variable used first 2 gets corrupted volatile unsigned int STAGE_1_CNT = 10; volatile unsigned int STAGE_2_CNT = 10; volatile unsigned int STAGE_30_CNT_L = 10; volatile unsigned int STAGE_30_CNT_H = 10; volatile unsigned int STAGE_31_CNT_L = 10; volatile unsigned int STAGE_31_CNT_H = 10; volatile unsigned int STAGE_32_CNT_L = 10; volatile unsigned int STAGE_32_CNT_H = 10; volatile unsigned int STAGE_33_CNT_L = 10; volatile unsigned int STAGE_33_CNT_H = 10; volatile unsigned int STAGE_4_CNT = 10; volatile unsigned int STAGE_5_CNT = 10; volatile unsigned int COUNTER = 0; volatile unsigned int Cycle_Count = 0; volatile unsigned int OP3_MF = 1; volatile unsigned char OP3_MF_CNT = 0; volatile unsigned int Bottel_Counter= 0; volatile unsigned int Set_Temp1 = 30; void main(void){ CS=0;SK=0;DI=1;DO=1; En_Write_93cxx(); // Enable the Memory Read_Variables(); // Read the Process v CS=0;SK=0;DI=0;DO=0; LED_1 = OUTPUT_LOW; LED_2 = OUTPUT_LOW; LED_3 = OUTPUT_LOW; LED_4 = OUTPUT_LOW; Initialize_LCD(); Clear_LCD(); Enable_Interrupts(); Welcomw_Note(); Delay_S(); Delay_S(); COUNTER = 0; // Display_Cycle_Count(Cycle_Count); while(1){ if(START_sw == LOW) {LED_1 = OUTPUT_LOW; LED_2 = OUTPUT_LOW; LED_3 = OUTPUT_LOW; LED_4 = OUTPUT_LOW; while(START_sw == LOW) Delay_MS(100); STAGE_1_Flag = HIGH; OP3_MF_CNT = 0; COUNTER = 0;} Stage_1(); if(Mode_sw == LOW)Switch_Control(); if(Temp_Counter1 == 25)Get_Temperature(); if(Temp_Counter1 == 50){Temp_Counter1 = 0;} } void Get_Temperature(){ unsigned char nib0,nib1,nib2,nib3,nib4; unsigned int temp; temp = Bottel_Counter; nib0 = temp%10;temp = temp/10; nib1 = temp%10;temp = temp/10; nib2 = temp%10;temp = temp/10; nib3 = temp%10;temp = temp/10; // nib4 = temp%10; Clear_LCD(); Display_String_LCD1(String_16,11); Write_LCD(' '); Write_LCD(nib3 + 0x30); Write_LCD(nib2 + 0x30); Write_LCD(nib1 + 0x30); Write_LCD(nib0 + 0x30); Next_Line_LCD(); Display_String_LCD1(String_18,10); Present_Value = 0; Present_Value += Nibble[4]; Present_Value += 10 * Nibble[3]; Present_Value += 100 * Nibble[2]; Present_Value += 1000 * Nibble[1]; Present_Value += 10000 * Nibble[0]; Present_Value = Present_Value/200; temp = Present_Value; nib0 = temp%10;temp = temp/10; nib1 = temp%10;temp = temp/10; nib2 = temp%10;temp = temp/10; // nib3 = temp%10;temp = temp/10; // nib4 = temp%10; Write_LCD(' '); // Write_LCD(nib4 + 0x30); // Write_LCD(nib3 + 0x30); Write_LCD(nib2 + 0x30); Write_LCD(nib1 + 0x30); Write_LCD(nib0 + 0x30); Write_LCD(' '); Write_LCD(' '); } void Stage_1(){ if(STAGE_1_Flag == HIGH){ LED_1 = OUTPUT_HIGH; if(COUNTER >= STAGE_1_CNT) {STAGE_2_Flag = HIGH; STAGE_1_Flag = LOW; COUNTER = 0;}} if(STAGE_2_Flag == HIGH){ LED_2 = OUTPUT_HIGH; if(COUNTER >= STAGE_2_CNT) {STAGE_30_Flag_H = HIGH; STAGE_2_Flag = LOW; COUNTER = 0;}} if(STAGE_30_Flag_H == HIGH){ LED_3 = OUTPUT_HIGH; if(COUNTER >= STAGE_30_CNT_H) {STAGE_30_Flag_H = LOW; STAGE_30_Flag_L = HIGH; COUNTER = 0;}} if(STAGE_30_Flag_L == HIGH){ LED_3 = OUTPUT_LOW; if(COUNTER >= STAGE_30_CNT_H) {STAGE_30_Flag_L = LOW; STAGE_31_Flag_H = HIGH; COUNTER = 0;}} if(STAGE_31_Flag_H == HIGH){ LED_3 = OUTPUT_HIGH; if(COUNTER >= STAGE_31_CNT_H) {STAGE_31_Flag_H = LOW; STAGE_31_Flag_L = HIGH; COUNTER = 0;}} if(STAGE_31_Flag_L == HIGH){ LED_3 = OUTPUT_LOW; if(COUNTER >= STAGE_31_CNT_H) {STAGE_31_Flag_L = LOW; STAGE_32_Flag_H = HIGH; COUNTER = 0;}} if(STAGE_32_Flag_H == HIGH){ LED_3 = OUTPUT_HIGH; if(COUNTER >= STAGE_32_CNT_H) {STAGE_32_Flag_H = LOW; STAGE_32_Flag_L = HIGH; COUNTER = 0;}} if(STAGE_32_Flag_L == HIGH){ LED_3 = OUTPUT_LOW; if(COUNTER >= STAGE_32_CNT_H) {STAGE_32_Flag_L = LOW; STAGE_33_Flag_H = HIGH; COUNTER = 0;}} if(STAGE_33_Flag_H == HIGH){ LED_3 = OUTPUT_HIGH; if(COUNTER >= STAGE_33_CNT_H) {STAGE_33_Flag_H = LOW; STAGE_33_Flag_L = HIGH; COUNTER = 0;}} if(STAGE_33_Flag_L == HIGH){ LED_3 = OUTPUT_LOW; if(COUNTER >= STAGE_33_CNT_H) {STAGE_33_Flag_L = LOW; OP3_MF_CNT++; if(OP3_MF == OP3_MF_CNT){STAGE_4_Flag = HIGH;OP3_MF_CNT =0;} else{STAGE_30_Flag_H = HIGH;} COUNTER = 0;}} if(STAGE_4_Flag == HIGH){ LED_2 = OUTPUT_LOW; if(COUNTER >= STAGE_4_CNT) {STAGE_4_Flag = LOW; STAGE_5_Flag = HIGH; Bottel_Counter = Read_93cxx_16bit(28); Bottel_Counter = Bottel_Counter + OP3_MF; Write_93cxx_16bit(28,Bottel_Counter); COUNTER = 0;}} if(STAGE_5_Flag == HIGH){ LED_4 = OUTPUT_HIGH; if(COUNTER >= STAGE_5_CNT) {STAGE_5_Flag = LOW; STAGE_6_Flag = HIGH; COUNTER = 0;}} if(STAGE_6_Flag == HIGH){ LED_4 = OUTPUT_LOW; LED_1 = OUTPUT_LOW; STAGE_6_Flag = LOW; Cycle_Count = Read_93cxx_16bit(30); Cycle_Count++; Write_93cxx_16bit(30,Cycle_Count); Get_Temperature(); // Display_Cycle_Count(Cycle_Count); } }
kapil, Please repost those message with formatting intact. Put a tag
BEFORE copying in your source, and then put
I think something got lost, so here we go where you in the below see [ use < where you in the below see ] use > kapil, Please repost those message with formatting intact. Put a tag [pre] BEFORE copying in your source, and then put [/pre] after it. Thanks. It's almost completely unreadable as it is.
Hehehe... That's what I get for not hitting preview first.
When you make a post, immediately above the 'Message:' box where you type are some 'Notes' which explain how to post code. A link is also given for "Tips for Posting Messages" which gives further details & examples. The link is: http://www.keil.com/forum/tips.asp
I am sorry Jay, Erik, A.W for a bad Posting Anyways i was abnle to locate the problem I am using 7135 ADC which outputs the data in nibbles( 5 nibbles for one conversion) Each nibble nibble when ready, signals a STROBE, which is recived as interrupt signal in the microcontroller. The 5th nibble when ready generates another signal D5 along with STROBE signal. SO in interrupt we need to check the status of D5 pin so as to syncronize the data The ISR used is following External_1() interrupt 2 using 3 { if(D5) nibble_reference = 0; //this is the starting,MSB is sent after this Nibble[nibble_reference] = In_Data; Nibble[nibble_reference] &= 0x0F; ++nibble_reference; } i have used a array Nibble[4] to collect the data and nibble_reference, a variable which guides the nibble to be placed at their right position. Now if their are supurious interrupts, generated because of any reason, then their is a big problem Because between 2 high signals of D5 we will recive more than 5 interrupts that means more than 5 times the increment of nibble_reference Which means we have gone outside the array Nibble[4] and destroying the next variable in line now the variables listing is like D:0x23 Nibble array[5]uchar D:0x28 nibble_reference uchar D:0x29 Present_Value uint D:0x2B STAGE_1_CNT uint D:0x2D STAGE_2_CNT uint D:0x23 ........... ........uint It is very clear the if D5 pulse is missed, it will destroy the nibble_reference variable and the more variavle in line. So STAGE_1_CNT and STAGE_2_CNT seems to be vunerable in the present senirio so finally it is a hardware problem but the software could be more robust which i will try to make. Anyways Thanks to all of you for you help. Thanks and Regards, Kapil