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how to dispaly the a/d value from PIC16F877 using visual basic in digital value

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Moderators: Ajay, Junied , abbas1707, Arun Kumar V, pdi33, Shailesh NAYAK, ۞ TPS ۞, shyam, sashijoseph

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norms

Sat Mar 01 2008, 10:24PM

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help needed urgently... why the code for my microcontroller wont detect a voltage? the leds don't turn on when i put 3vs as an analog input. everyone help me? and then the vb code for displaying the reading...

Ajay

Sun Mar 02 2008, 06:35AM

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i need to see the circuit atleast..

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sashijoseph

Sun Mar 02 2008, 12:04PM

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Joined: Mon Feb 04 2008, 06:26PM

Posts: 554
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On close examination of your code,this is the logic I figured out.....

for(;;)
{
if(usart receive buffer is full)...read usart....volts_out=value read
{ if(volts_out=511)....light up some leds and loop till receive buffer is full again
elseif(volts_out<511)....light up some leds and loop till receive buffer is full again
elseif(volts_out>511)....light up some leds and loop till receive buffer is full again
elseif(volts_out=get_adc)...read adc value,store it in EEPROM,read the stored
EEPROM value and send it to USART
}
else...PORTB=0xFF
}

Instead of the ADC you are reading in the value "Volts_out" from the USART....why?
Moreover you need to send in some value from the PC to the USART in order for the 1st ' if' statement to trigger.(if(usart receive buffer is full))
And then the variable get_adc...you are comparing volts_out to it before providing it with an initial value(you've only declared it "unsigned int get_adc;",not initialised it).

Look at the code below...this is how it should be.

unsigned int adc_val;
unsigned char volts_out;

void main()
{
USART_Init(9600);
ADCON1 = 0x80;
TRISA = 0xFF; // PORTA is input
TRISB = 0; // PORTB is output
PORTB = 0;

while (1)
{
adc_val = ADC_Read(2);
volts_out = adc_val * 5/1023;
USART_Write(volts_out);
if(adc_val==511)
{PORTB = 0xFF;}
else if(adc_val<511)
{PORTB = 0x0F;}
else
{PORTB = 0xF0;}
Delay_ms(5000);
}

}

Let there be music........

norms

Sun Mar 02 2008, 11:46PM

Registered Member #6079

Joined: Sat Feb 16 2008, 12:34AM

Posts: 28
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at this moment my current code for my microcontroller 16F877, please correct it and write the code if you don't mind... please... really reallly need it.

void main()
{
int limit = 512;
int vout;
int adc;
int x;
int value;
int temp1;
int temp2;
int exit = 1;

Usart_Init(2400);
ADCON0 = 0x80;
ADCON1 = 0x80;
ADCON0.ADON = 1; // Enables A/D Conversion
TRISB = 0;
PORTB = 0;
RCSTA = 0x90;
TXSTA = 0x24;
Delay_ms(100);

for(;;)
{
if(Usart_Data_Ready())
{
exit=1;
PORTB=0;
vout=Usart_Read();
Delay_ms(100);

if(vout == 512) // Within the 240 Voltage Range, equal to 2.5 volts
{
do
{
PORTB.F1 = 1;
PORTB.F2 = 1;
PORTB.F3 = 1;
PORTB.F4 = 1;
PORTB.F5 = 1;
PORTB.F6 = 1;
PORTB.F7 = 1;
Delay_ms(1000);
if(Usart_Data_Ready())
{
exit=0;
}
}
while(exit);
}
else if(vout > 512) // Greater than 240 Volts, greater than 2.5 volts
{
do
{
PORTB.F1 = 1;
PORTB.F3 = 1;
PORTB.F5 = 1;
PORTB.F7 = 1;
Delay_ms(1000);
if(Usart_Data_Ready())
{
exit=0;
}
}
while(exit);
}
else if (vout < 512) // Less than 240 volts, less than 2.5 volts
{
do
{
PORTB.F2 = 0;
PORTB.F4 = 0;
PORTB.F6 = 0;
Delay_ms(1000);
if (Usart_Data_Ready())
{
exit = 0;
}
}
while(exit);
}
else if (vout == 0)
{
do
{
PORTB.F1=0;
PORTB.F2=0;
PORTB.F3=0;
PORTB.F4=0;
PORTB.F5=0;
PORTB.F6=0;
PORTB.F7=0;
if(Usart_Data_Ready())
{
exit=0;
}
}
while(exit);
}
else if(vout == adc)
{
do
{
ADRESH=0;
ADRESL=0;
ADCON0.GO=1;
Delay_ms(100);
value=Adc_Read(0);
Delay_ms(100);
exit=0;
temp1=ADRESH;
temp2=ADRESL;
Delay_ms(1000);
Eeprom_Write(0,temp1);
Delay_ms(20);
Eeprom_Write(1,temp2);
Delay_ms(70);
Usart_Write(Eeprom_Read(0));
Delay_ms(20);
Usart_Write(Eeprom_Read(1));
Delay_ms(50);
if(Usart_Data_Ready())
{
exit=0;
}
}
while(exit);
}
}
else
{
PORTB=0xff;
}
}
}

norms

Sun Mar 02 2008, 11:48PM

Registered Member #6079

Joined: Sat Feb 16 2008, 12:34AM

Posts: 28
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my vb code... please check and correct it... thank you very much guys...

Private Sub CmdExit_Click()
If MSComm1.PortOpen = True Then
MSComm1.PortOpen = False
End If
End
End Sub
Private Sub Form_Load()
MSComm1.InputLen = 0
MSComm1.CommPort = 1
MSComm1.Settings = "2400,N,8,1"
End Sub
Private Sub Timer1_Timer()
Dim BytesToRead As Integer
Dim adc As Variant
MSComm1.PortOpen = True
BytesToRead = 1
Do
DoEvents
Loop Until MSComm1.InBufferCount = BytesToRead
adc = MSComm1.Input
Text1.Text = (((Asc(adc) * 0.01) * 230) / 2.5) & " Volts AC"
MSComm1.PortOpen = False
End Sub

norms

Mon Mar 03 2008, 12:09AM

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Joined: Sat Feb 16 2008, 12:34AM

Posts: 28
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this is my circuit

norms

Mon Mar 03 2008, 12:32AM

Registered Member #6079

Joined: Sat Feb 16 2008, 12:34AM

Posts: 28
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the Tx and Rx were put incorrectly... Rx should in the Tx place...

sashijoseph

Mon Mar 03 2008, 11:17AM

Registered Member #5870

Joined: Mon Feb 04 2008, 06:26PM

Posts: 554
Thanked 124 times in 117 posts

Like I pointed out ealier your PIC code won't work.For eg.

CODE:

if(Usart_Data_Ready())

why are you checking the (PIC's) serial port input buffer?Are you sending sth into the PIC's serial port?If not then why use this check?

Then you have

CODE:

vout=Usart_Read();

You should be getting the value from the ADC rather than the serial port.

Similarly there are plenty of flaws.......

Look at the code below.This is all you need to read in ADC value and send it as two bytes to the PC's serial port.

unsigned int adc_val;
unsigned char low_byte,hi_byte;
void main()
{
USART_Init(9600);
ADCON1 = 0;
TRISA = 0xFF; // PORTA is input
TRISB = 0; // PORTB is output
PORTB = 0;

while (1)
{
adc_val = ADC_Read(2); //get ADC value
low_byte = adc_val; //split the 2-byte integer into 2 separate bytes
hi_byte = adc_val >> 8; //for sending to pc serial port
USART_Write(low_byte); //send the 1st (lower) byte
USART_Write(hi_byte); //send the upper byte
if(adc_val==511) //if ADC value read in is 511
{PORTB = 0xFF;} //display some LED's on PORTB
else if(adc_val<511)
{PORTB = 0x0F;}
else
{PORTB = 0xF0;}
Delay_ms(5000); //gather a sample after 5 secs.
}
}

[ Edited Mon Mar 03 2008, 11:18AM ]

Let there be music........

norms

Mon Mar 03 2008, 11:11PM

Registered Member #6079

Joined: Sat Feb 16 2008, 12:34AM

Posts: 28
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thanks sashijoseph for the help. appreciate it very much... ill test it tonight ill keep in touchwith you. you save my life...

norms

Mon Mar 03 2008, 11:35PM

Registered Member #6079

Joined: Sat Feb 16 2008, 12:34AM

Posts: 28
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sashijoseph wrote ...

Like I pointed out ealier your PIC code won't work.For eg.

CODE:

if(Usart_Data_Ready())

why are you checking the (PIC's) serial port input buffer?Are you sending sth into the PIC's serial port?If not then why use this check?

Then you have

CODE:

vout=Usart_Read();

what happened to the USART_Write(volts_out)? in your first correction you have it, then now its gone, replace by the low and high byte... please enlightened me with this...

then in my vb pro, do i need to change the BytesToRead = 1 to 2? and then the "adc=MSComm1.Input"
what will be my input here? thanks