Hi all... i need to print a value of pointer variable in 16x2 LCD... for Eg.
void main() { int *a = 20; int b; *a=&b; print_LCD(value of pointer variable a) }
here is a simple example where i have declared a pointer variable 'a' whoes value is 20. and then i stored the value of pointer variable at the address of variable b. but i need to print the value of pointer variable on LCD screen. how can i do this.... can anybody help me please....
Thanks for the help... actually i am new to programming and i was actually trying to understand what exactly pointer are.... i need a small help from you... here i am trying to understand how can i interface RTC with 89s52... here is a part of code...
unsigned char sec, min, hour, day, month, year, void DS1307_GetTime(unsigned char *h_ptr,unsigned char *m_ptr,unsigned char *s_ptr) { I2C_Start(); // Start I2C communication DS1307_Write(DS1307_ID); // connect to DS1307 by sending its ID on I2c Bus DS1307_Write(SEC_ADDRESS); // Request Sec RAM address at 00H I2C_Stop(); // Stop I2C communication after selecting Sec Register I2C_Start(); // Start I2C communication DS1307_Write(0xD1); // connect to DS1307( under Read mode) //by sending its ID on I2c Bus *s_ptr = DS1307_Read(); I2C_Ack(); // read second and return Positive ACK *m_ptr = DS1307_Read(); I2C_Ack(); // read minute and return Positive ACK *h_ptr = DS1307_Read(); I2C_NoAck(); // read hour and return Negative/No ACK I2C_Stop(); // Stop I2C communication after reading the Time } void DS1307_GetDate(unsigned char *d_ptr,unsigned char *m_ptr,unsigned char *y_ptr) { I2C_Start(); // Start I2C communication DS1307_Write(DS1307_ID); // connect to DS1307 by sending its ID on I2c Bus DS1307_Write(DATE_ADDRESS); // Request DAY RAM address at 04H I2C_Stop(); // Stop I2C communication after selecting DAY Register I2C_Start(); // Start I2C communication DS1307_Write(0xD1); // connect to DS1307( under Read mode) // by sending its ID on I2c Bus *d_ptr = DS1307_Read(); I2C_Ack(); // read Day and return Positive ACK *m_ptr = DS1307_Read(); I2C_Ack(); // read Month and return Positive ACK *y_ptr = DS1307_Read(); I2C_NoAck(); // read Year and return Negative/No ACK I2C_Stop(); // Stop I2C communication after reading the Time } void main() { DS1307_Init(); DS1307_SetTime(0x10,0x40,0x20); DS1307_SetDate(0x12,0x07,0x14); while(1) { DS1307_GetTime(&hour,&min,&sec); DS1307_GetDate(&day,&month,&year); } }
i am not able to understand this part of code... with the help of void DS1307_GetTime function i am storing the values like Hours, minutes and seconds in pointer variables (unsigned char *h_ptr,unsigned char *m_ptr,unsigned char *s_ptr) and the same goes for DS1307_GetDate. but now when i wrote DS1307_GetTime(&hour,&min,&sec); DS1307_GetDate(&day,&month,&year); in main function... i am not able to understand that if this function is storing the value of pointer *h_ptr, *m_ptr..... (which is the actual time)to the address of variable hours, min, sec. or it is storing the value to hours, min, sec. or something else.. can you please explain what is exactly happening...
A pointer is a variable that stores a memory address. So your variable "a" is "a pointer to int" so it stores the address of a memory cell capable of storing an integer.
And the indirection of the pointer allows you to access the memory at that address. So the indirection of "a" accesses an integer variable storage space.
sorry... but did not got your point....
Try with something simpler. Then, once you've mastered that, try something a little more complex. Maybe something like adding two numbers together.