How to display dot on 7-seg , 4 digit

[chai98a]

we try to used 7-seg 4 digit.
but we don't know how to display dot (Ex. 45.46)

[ardhuru]

Hi,

Think of the display as a 8 segment display, where the eighth 'segment' is the decimal. Keep this 'segment' off in all the digits, except for the one where you want the decimal to show.

Regards,

Anand

[chai98a]

Need more informatiom
here is may code :for display 7-seg

For i = 0 To 3 ' Loop through 4 digits
n = Value Dig i ' Get digit to display
Gosub display1 ' Display the value
NEXT I
goto mainloop

display1:
Digits = $ff ' All digits off to prevent ghosting

' Convert binary number in n to segments for LED
' COM ANODE 1234567890

Lookup n, [$3F,$06, $5B, $4F, $66, $6D, $7D, $07, $7F, $6F], Segments

' Set digit pin i to 0 (on) and the rest of the pins to 1 (off)

Digits = ~Dcd i

Return

[paul borgmeier]

Your code is not complete! You have a nice lookup table but you do not use the outcome from the table? Where do you use the variable Segments? Is Digits the name of your port? (which you imply when you set it = $FF at one point)

Also, the way you have it (Digits =~DCD i)
Digits can only be

11111110
11111101
11111011
11110111

Although it is late here, your code makes no sense to me

However, if Digits does control the port, it looks like you can turn your DP on by issuing this
Digits.7 = 0
(provided the wire or trace from the DP goes to pin 7 of your port).

Post complete code for better shot at guessing what you are trying to do.

[paul borgmeier]

ok it's not 4am (it's 8:15am)

i see what the dcd command is doing (common anode as you noted).

For the digit you want to have the dp on try

Sements.7 = 0 (provided your PORT.7 pin is tied to the DP via wire or trace


Good Luck

[paul borgmeier]

One more time - after a proper days rest, I have no clue what your code does; it looks to me to be partly written for common anode displays ($3F=1) and partly written for common cathode displays (Digits = ~DCD i). The Segments.7=0 should work (right after your lookup table) for the digit you want the DP to be on. Please post full code or schematic for more definite help.
Again, Good Luck

[chai98a]

Hi paul borgmeier
Now I try to show temp with DS1820 on 7 seg 4 digit
Below is code , I can read data temp from ds1820 and send to RS232 -->OK but canot to diplay to 7 Seg. Ex 29.05C

Code :
Define LOADER_USED 1
DEFINE OSC 4
@ Device pic16F877, xt_OSC, BOD_OFF, PWRT_ON, WDT_OFF, PROTECT_OFF,WRT_ON

Segments Var PORTC
Digits Var PORTD

i Var Byte
n Var Byte
Value Var Word


TRISc = $00 ' Set segment pins to output
TRISd = $f0 ' Set digit pins to output


' Allocate variables
command var byte ' Storage for command
J var byte ' Storage for loop counter
temp var word ' Storage for temperature
DQ var PORTd.4 ' Alias DS1820 data pin
DQ_DIR var TRISd.4 ' Alias DS1820 data direction pin

TRISc = $00 ' Set segment pins to output
TRISd = $f0 ' Set digit pins to output
TrisB = $00
Portb = $00
OPTION_REG = $55 ' Set TMR0 configuration 1:64
INTCON = $A0 ' Enable TMR0 interrupts
On Interrupt Goto display

ADCON1 = 7 ' Set PORTA and PORTE to digital

' Lcdout $fe, 1, "Temp in degrees C" ' Display sign-on message
'debug ====
DEFINE HSER_RCSTA 90h
DEFINE HSER_TXSTA 24h
DEFINE HSER_SPBRG 12 ' 19200 Bauds ,4 m
'debug ====

' Mainloop to read the temperature and display on LCD
mainloop:
Gosub init1820 ' Init the DS1820

command = $cc ' Issue Skip ROM command
Gosub write1820

command = $44 ' Start temperature conversion
Gosub write1820

Pause 2000 ' Wait 2 seconds for conversion to complete

Gosub init1820 ' Do another init

command = $cc ' Issue Skip ROM command
Gosub write1820

command = $be ' Read the temperature
Gosub write1820
Gosub read1820

'Display the decimal temperature
'Lcdout $fe, 1, dec (temp >> 1), ".", dec (temp.0 * 5), " degrees C"
'HSEROUT ["Temp = ",dec (temp>>1),".", dec (temp.0*5)," C",13,10]
Goto mainloop ' Do it forever


' Initialize DS1820 and check for presence
init1820:
Low DQ ' Set the data pin low to init
Pauseus 500 ' Wait > 480us
DQ_DIR = 1 ' Release data pin (set to input for high)

Pauseus 100 ' Wait > 60us
If DQ = 1 Then
'Lcdout $fe, 1, "DS1820 not present"
Pause 500
Goto mainloop ' Try again
Endif
Pauseus 400 ' Wait for end of presence pulse
Return


' Write "command" byte to the DS1820
write1820:
For j = 1 to 8 ' 8 bits to a byte
If command.0 = 0 Then
Gosub write0 ' Write a 0 bit
Else
Gosub write1 ' Write a 1 bit
Endif
command = command >> 1 ' Shift to next bit
Next j
Return

' Write a 0 bit to the DS1820
write0:
Low DQ
Pauseus 60 ' Low for > 60us for 0
DQ_DIR = 1 ' Release data pin (set to input for high)
Return

' Write a 1 bit to the DS1820
write1:
Low DQ ' Low for < 15us for 1
@ nop ' Delay 1us at 4MHz
DQ_DIR = 1 ' Release data pin (set to input for high)
Pauseus 60 ' Use up rest of time slot
Return


' Read temperature from the DS1820
read1820:
For J = 1 to 16 ' 16 bits to a word
temp = temp >> 1 ' Shift down bits
Gosub readbit ' Get the bit to the top of temp
Next J
Return

' Read a bit from the DS1820
readbit:
temp.15 = 1 ' Preset read bit to 1
Low DQ ' Start the time slot
@ nop ' Delay 1us at 4MHz
DQ_DIR = 1 ' Release data pin (set to input for high)
If DQ = 0 Then
temp.15 = 0 ' Set bit to 0
Endif
Pauseus 60 ' Wait out rest of time slot
Return

'================== 7 seg ment display ==============================
disable
display:
INTCON.2 = 0 'clear the interrupt flag

VALUE = (temp >>1)+(temp.0 * 5)

For i = 0 To 3 ' Loop through 4 digits
n = Value Dig i ' Get digit to display
Gosub display1 ' Display the value
NEXT I

goto mainloop

display1:
Digits = $ff ' All digits off to prevent ghosting

' Convert binary number in n to segments for LED
' COM ANODE 1234567890
Lookup n, [$3F,$06, $5B, $4F, $66, $6D, $7D, $07, $7F, $6F, $77, $7C, $39, $5E, $79, $71], Segments
' Set digit pin i to 0 (on) and the rest of the pins to 1 (off)

Digits = ~Dcd i

Return
enable
End

[chai98a]

[QUOTE=chai98a;30011]Hi paul borgmeier
Now I try to show temp with DS1820 on 7 seg 4 digit
Below is code , I can read data temp from ds1820 and send to RS232 -->OK but canot to diplay to 7 Seg. Ex 29.5C

How to show number , dot and character on display ??

Code :
Define LOADER_USED 1
DEFINE OSC 4
@ Device pic16F877, xt_OSC, BOD_OFF, PWRT_ON, WDT_OFF, PROTECT_OFF,WRT_ON

Segments Var PORTC
Digits Var PORTD

i Var Byte
n Var Byte
Value Var Word


TRISc = $00 ' Set segment pins to output
TRISd = $f0 ' Set digit pins to output


' Allocate variables
command var byte ' Storage for command
J var byte ' Storage for loop counter
temp var word ' Storage for temperature
DQ var PORTd.4 ' Alias DS1820 data pin
DQ_DIR var TRISd.4 ' Alias DS1820 data direction pin

TRISc = $00 ' Set segment pins to output
TRISd = $f0 ' Set digit pins to output
TrisB = $00
Portb = $00
OPTION_REG = $55 ' Set TMR0 configuration 1:64
INTCON = $A0 ' Enable TMR0 interrupts
On Interrupt Goto display

ADCON1 = 7 ' Set PORTA and PORTE to digital

' Lcdout $fe, 1, "Temp in degrees C" ' Display sign-on message
'debug ====
DEFINE HSER_RCSTA 90h
DEFINE HSER_TXSTA 24h
DEFINE HSER_SPBRG 12 ' 19200 Bauds ,4 m
'debug ====

' Mainloop to read the temperature and display on LCD
mainloop:
Gosub init1820 ' Init the DS1820

command = $cc ' Issue Skip ROM command
Gosub write1820

command = $44 ' Start temperature conversion
Gosub write1820

Pause 2000 ' Wait 2 seconds for conversion to complete

Gosub init1820 ' Do another init

command = $cc ' Issue Skip ROM command
Gosub write1820

command = $be ' Read the temperature
Gosub write1820
Gosub read1820

'Display the decimal temperature
'Lcdout $fe, 1, dec (temp >> 1), ".", dec (temp.0 * 5), " degrees C"
'HSEROUT ["Temp = ",dec (temp>>1),".", dec (temp.0*5)," C",13,10]
Goto mainloop ' Do it forever


' Initialize DS1820 and check for presence
init1820:
Low DQ ' Set the data pin low to init
Pauseus 500 ' Wait > 480us
DQ_DIR = 1 ' Release data pin (set to input for high)

Pauseus 100 ' Wait > 60us
If DQ = 1 Then
'Lcdout $fe, 1, "DS1820 not present"
Pause 500
Goto mainloop ' Try again
Endif
Pauseus 400 ' Wait for end of presence pulse
Return


' Write "command" byte to the DS1820
write1820:
For j = 1 to 8 ' 8 bits to a byte
If command.0 = 0 Then
Gosub write0 ' Write a 0 bit
Else
Gosub write1 ' Write a 1 bit
Endif
command = command >> 1 ' Shift to next bit
Next j
Return

' Write a 0 bit to the DS1820
write0:
Low DQ
Pauseus 60 ' Low for > 60us for 0
DQ_DIR = 1 ' Release data pin (set to input for high)
Return

' Write a 1 bit to the DS1820
write1:
Low DQ ' Low for < 15us for 1
@ nop ' Delay 1us at 4MHz
DQ_DIR = 1 ' Release data pin (set to input for high)
Pauseus 60 ' Use up rest of time slot
Return


' Read temperature from the DS1820
read1820:
For J = 1 to 16 ' 16 bits to a word
temp = temp >> 1 ' Shift down bits
Gosub readbit ' Get the bit to the top of temp
Next J
Return

' Read a bit from the DS1820
readbit:
temp.15 = 1 ' Preset read bit to 1
Low DQ ' Start the time slot
@ nop ' Delay 1us at 4MHz
DQ_DIR = 1 ' Release data pin (set to input for high)
If DQ = 0 Then
temp.15 = 0 ' Set bit to 0
Endif
Pauseus 60 ' Wait out rest of time slot
Return

'================== 7 seg ment display ==============================
disable
display:
INTCON.2 = 0 'clear the interrupt flag

VALUE = (temp >>1)+(temp.0 * 5)

For i = 0 To 3 ' Loop through 4 digits
n = Value Dig i ' Get digit to display
Gosub display1 ' Display the value
NEXT I

goto mainloop

display1:
Digits = $ff ' All digits off to prevent ghosting

' Convert binary number in n to segments for LED
' COM ANODE 1234567890
Lookup n, [$3F,$06, $5B, $4F, $66, $6D, $7D, $07, $7F, $6F, $77, $7C, $39, $5E, $79, $71], Segments
' Set digit pin i to 0 (on) and the rest of the pins to 1 (off)

Digits = ~Dcd i

Return
enable
End

[paul borgmeier]

I see - the PNPs (which I did not know about) threw me off. It appears proper for Common Anode.

Try this:
1) On your buffer, tie 1 and 19 low so they do not float.
2) The 3rd from last line of your code - change "Return" to "Resume" (See manual section on On Interrupt for details).

Please report back progress so that others following this can get closure.

EDIT:
3) Your lookup values need to be inverted - as written they are for common cathode displays. Change to ($C0, $F9, $A4, etc) where the segments you want off are high and the segments you want on are low.
4) To turn on the decimal point on the second digit, insert right after the lookup table
if i = 1 then Segments.7 = 0 (or if the DP is always to be on you could do this in hardware by disconnecting RC7 from D7 on U2 and connecting RD1 to D7 on U2 (in addition to RD1 going to the Base of Q2))

[sayzer]

Here is the full list of Common Cathode:

Starting from 0 to 9.

$c0, $F9, $A4, $B0, $99, $92, $82, $F8, $80, $90



------------------------------

[paul borgmeier]

Sayzer,
You bolded Common Cathode as if it is for sure - you must mean Common Anode. Common Cathode requires the segment to be high to be on while Common Anode requires Segments to be low to be on. His buffer is non-inverting. (Your set looks correct though - I left a little for the OP to work out as a learning exercise but now he is close to set).

EDIT:
Oh, for thoroughness, have you considered testing DT's suggested gif animator at 1/4 scale?:) :)

[sayzer]

Hi Paul,

My set is for Common Cathode.
I now see what you meant.

Let me check for Common Anode...Should be somewhere in my HDDs.

BTW; I am just testing the animator and will remove it now. I think is is slowing down the CPU when there is more then one running.

-----------------

[paul borgmeier]

Sayzer,

You have it correct for Common Anode in post #10 (at least the first three are correct - I didn't check your others). The OP should be grateful for your help because you probably saved him hours of work and frustration)

Best Wishes

[sayzer]

Paul,

Ok, here is the clarification.
(from 0 to 9)

Common Anode : $c0, $F9, $A4, $B0, $99, $92, $82, $F8, $80, $90

Common Cathode : $3F, $06, $5B, $4F, $66, $6D, $7D, $07, $7F, $6F


Using Dot or not changes from set to set.
These are what I use.




----------------------------

[chai98a]

Hi paul borgmeier
I'm not understand for item 1
1) On your buffer, tie 1 and 19 low so they do not float.

For item 4 , as you advise with modify some hard were right, Do you have other way with out modify hard or not.

[paul borgmeier]

1) On U2, pins 1 and 19 both must be connected to GND (or held low) in order for the input to be placed on the output of the buffer. If either pin is high, then the entire output of U2 will be tri-stated (high impedance). Floating means leaving pins NOT or unconnected, which is not good because they can "do what they want" - stay low, drift high, or worse go somewhere in-between. Just connect both 1 and 19 to GND and you will be set.

4) The DP can be set entirely in software using the added line of code OR it can be set in hardware. If you cannot change your circuit, then use the software version. Just add the IF-THEN statement shown in 4) and you should have a DP turned on.

[chai98a]

Hi paul borgmeier
Thank for you reply..
Soory! for circuit not clear for you.. , we used 7 seg COM Cathode..
This circuit i have test with time counter alredly done no problem.
But after we apply Display sub to 1820 reading ,so got problem display cannot show reading on 7 seg display..

Pls any xepert advise >> very confiuse for me

code: time conter
DEFINE LOADER_USED 1
DEFINE OSC 4

@ Device pic16F877, xt_OSC, BOD_OFF, PWRT_ON, WDT_OFF, PROTECT_OFF,WRT_ON

Segments Var PORTC
Digits Var PORTD

i Var Byte
n Var Byte
J var byte
Value Var WORD
Hr var byte
Minute var BYTE ' Define minute variable
Second var BYTE ' Define second variable
Ticks var byte ' Define pieces of seconds variable
D_up var byte

clear ' clear all RAM (sets all VAR declarations to zero)
TRISc = $00 ' Set segment pins to output
TRISd = $f0 ' Set digit pins to output
TrisB = $00
Portb = $00
OPTION_REG = $55 ' Set TMR0 configuration 1:64
INTCON = $A0 ' Enable TMR0 interrupts
On Interrupt Goto int0

mainloop:
goto display

goTo mainloop ' Do it forever


disable
int0:
Ticks = Ticks + 1 ' Count pieces of seconds
If Ticks < 61 Then goto ExitInterrupt ' 61 ticks per second

' One second elasped - update time
Ticks = 0
Second = Second + 1
If Second >= 60 Then
Second = 0
Minute = Minute + 1
If Minute >= 60 Then
D_up =1
Minute = 0
Hr =hr + 1
If Hr >= 60 Then
Hr = 0

endif
endif
Endif

goto mainloop

display:

If D_up = 1 then
VALUE = ((Hr*100)+Minute)
goto dup
else
VALUE = ((minute*100)+second)
endif

dup:
For i = 0 To 3 ' Loop through 4 digits
n = Value Dig i ' Get digit to display

' Gosub display1 ' Display the value
Digits = $ff

Lookup n, [$3F, $06, $5B, $4F, $66, $6D, $7D, $07, $7F, $6F,_
$77, $7C, $39, $5E, $79, $71, $0FF], Segments
Digits = ~Dcd i

NEXT I
goto mainloop

ExitInterrupt:
INTCON.2 = 0 'clear the interrupt flag
Resume
enable


code : 1820 reading
Define LOADER_USED 1
DEFINE OSC 4
@ Device pic16F877, xt_OSC, BOD_OFF, PWRT_ON, WDT_OFF, PROTECT_OFF,WRT_ON

Segments Var PORTC
Digits Var PORTD

i Var Byte
n Var Byte
Value Var Word

TRISc = $00 ' Set segment pins to output
TRISd = $f0 ' Set digit pins to output

' Allocate variables
command var byte ' Storage for command
J var byte ' Storage for loop counter
temp var word ' Storage for temperature
DQ var PORTd.4 ' Alias DS1820 data pin
DQ_DIR var TRISd.4 ' Alias DS1820 data direction pin

TRISc = $00 ' Set segment pins to output
TRISd = $f0 ' Set digit pins to output
TrisB = $00
Portb = $00
OPTION_REG = $55 ' Set TMR0 configuration 1:64
INTCON = $A0 ' Enable TMR0 interrupts
On Interrupt Goto display

ADCON1 = 7 ' Set PORTA and PORTE to digital
'debug ====
DEFINE HSER_RCSTA 90h
DEFINE HSER_TXSTA 24h
DEFINE HSER_SPBRG 12 ' 19200 Bauds ,4 m
'debug ====
' Mainloop to read the temperature and display on LCD
mainloop:
Gosub init1820 ' Init the DS1820

command = $cc ' Issue Skip ROM command
Gosub write1820

command = $44 ' Start temperature conversion
Gosub write1820

Pause 2000 ' Wait 2 seconds for conversion to complete

Gosub init1820 ' Do another init

command = $cc ' Issue Skip ROM command
Gosub write1820

command = $be ' Read the temperature
Gosub write1820
Gosub read1820

'Display the decimal temperature
HSEROUT ["Temp = ",dec (temp>>1),".", dec (temp.0*5)," C",13,10]
Goto mainloop ' Do it forever
' Initialize DS1820 and check for presence
init1820:
Low DQ ' Set the data pin low to init
Pauseus 500 ' Wait > 480us
DQ_DIR = 1 ' Release data pin (set to input for high)

Pauseus 100 ' Wait > 60us
If DQ = 1 Then
'Lcdout $fe, 1, "DS1820 not present"
Pause 500
Goto mainloop ' Try again
Endif
Pauseus 400 ' Wait for end of presence pulse
Return
' Write "command" byte to the DS1820
write1820:
For j = 1 to 8 ' 8 bits to a byte
If command.0 = 0 Then
Gosub write0 ' Write a 0 bit
Else
Gosub write1 ' Write a 1 bit
Endif
command = command >> 1 ' Shift to next bit
Next j
Return

' Write a 0 bit to the DS1820
write0:
Low DQ
Pauseus 60 ' Low for > 60us for 0
DQ_DIR = 1 ' Release data pin (set to input for high)
Return

' Write a 1 bit to the DS1820
write1:
Low DQ ' Low for < 15us for 1
@ nop ' Delay 1us at 4MHz
DQ_DIR = 1 ' Release data pin (set to input for high)
Pauseus 60 ' Use up rest of time slot
Return


' Read temperature from the DS1820
read1820:
For J = 1 to 16 ' 16 bits to a word
temp = temp >> 1 ' Shift down bits
Gosub readbit ' Get the bit to the top of temp
Next J
Return

' Read a bit from the DS1820
readbit:
temp.15 = 1 ' Preset read bit to 1
Low DQ ' Start the time slot
@ nop ' Delay 1us at 4MHz
DQ_DIR = 1 ' Release data pin (set to input for high)
If DQ = 0 Then
temp.15 = 0 ' Set bit to 0
Endif
Pauseus 60 ' Wait out rest of time slot
Return

'================== 7 seg ment display ==============================
disable
display:

VALUE = (temp >>1)

For i = 0 To 3 ' Loop through 4 digits
n = Value Dig i ' Get digit to display

' Gosub display1 ' Display the value
Digits = $ff
Lookup n, [$3F, $06, $5B, $4F, $66, $6D, $7D, $07, $7F, $6F,_
$77, $7C, $39, $5E, $79, $71, $0FF], Segments
Digits = ~Dcd i

NEXT I
INTCON.2 = 0 'clear the interrupt flag
goto mainloop
Resume
enable
End

[paul borgmeier]

Chai98a,

Soory! for circuit not clear for you.. , we used 7 seg COM Cathode..
It is clear to me as presented. Is it wrong? I did not assume Common Anode – you told me it was Common Anode (see your third post). The transistors shown in your schematic and the code line Digits=~DCD i also imply Common Anode.

Your code is largely not commented
Your schematic is not complete

I spent considerable time sorting all this out and now I will not offer more until you give more detail.

1) Is the the schematic fragment correct?
2)What is the P/N of Q1-Q4 are they really PNP?
3)What troubles are you having (i.e., does the display light up (at all)? wrong temp? junk? just missing DP?)
4) Are pins 1 and 19 tied low on U2?
5) With the code you posted in #17, how does temp get set? (I don't believe it ever does)

From post #7
I can read data temp from ds1820 and send to RS232 -->OK but canot to diplay to 7 Seg. Ex 29.5C
and from post #17

This circuit i have test with time counter alredly done no problem

it appears to me you have everything you need – your circuit works and you must have code to drive it; your temperature sensor reads temperature correctly.

I am not sure how to help you until you provide more information

[sayzer]

Paul, let me help you here a little.

I see you are trying to help; all of us went through the same process that Chai98a is now going through.
I am sure when Chai98a gets more experienced, he will also help others on this forum as much as he can.


Chai98a, are you using standard 4x7 segments LED display? or it is one of those LARGE ones?

Also, why are you using 74HC ?

Based on your answer, I will post a schematic for you.

---------------------

[ardhuru]

With this talk of CC and CA displays, I'd like to share a technique I've used and found very useful.

I like to design PCBs that would work with CA as well as CC displays; the only hardware difference between the two is whether to tie the emitters of the driver transistors to +5 or ground, depending on the display.

So, provide for a jumper that lets you select between the two.

AND, use this signal as an input to the PIC to tell it what kind of display is being used. Keep 2 lookup tables in the code, one for CA and the other for CC; depending on the state of the jumpered signal, the code uses the corresponding lookup.

During production time, then, it becomes easier as one could use either CA or CC, without having to change the code; just connect the common line to +5 or Gnd, and it will work.

Regards,

Anand

[paul borgmeier]

Paul, let me help you here a little.
I do not need help ... the OP does :) Anyone is welcome to contribute and chime in.

[chai98a]

Hi sayzer and paul borgmeier
# Is the the schematic fragment correct?
-see attached
# What is the P/N of Q1-Q4 are they really PNP?
-TR # BC557
# What troubles are you having (i.e., does the display light up (at all)? wrong temp? junk? just missing DP?)
-found Junk display,flash ,missing dp
# Are pins 1 and 19 tied low on U2?
- yes
# are you using standard 4x7 segments LED display?
- we used standard 7 seg.
# why are you using 74HC ?
- I did follow some sample on web

[paul borgmeier]

I do not need help ... the OP does :) Anyone is welcome to contribute and chime in.
Maybe I do need help - I need to sharpen/review my PNP circuit abilites a bit and will comment soon.

Others welcome to comment.

EDIT:
based on an offlist conversation with another member

[paul borgmeier]

Sayzer - where did you go ... I thought you were helping me here? :):).

Chai98a,
As Sayzer was hinting at in his "Large" post, if you are using a "standard" common-sized common anode display, you might want to simplify your circuit and follow something like figure 6 of the below link. Your schematic as draw is not correct and makes little sense (to me).

http://picbasic.com/resources/articles/ledart.htm

Is this an option or are you locked into your hardware as shown in your earlier post?

[sayzer]

We had a long holiday here in Turkey.

Sorry Paul. I was busy with my .... (fill in the blank).


I will post some concept schematics, using PNP, NPN and ULN type of drivers.

-----------------

[chai98a]

Now we finish 7 seg display temp form ds1820 about 90%
But we stil have porblem with display fashing and i have try at 20 Mhz cannot resolve it



Code:

Define LOADER_USED 1
DEFINE OSC 4
@ Device pic16F877A, xt_OSC, BOD_OFF, PWRT_ON, WDT_OFF, PROTECT_OFF 'WRT_On

Segments Var PORTC
Digits Var PORTD

i Var Byte
n Var Byte
Value Var Word

' Allocate variables
command var byte ' Storage for command
J var byte ' Storage for loop counter
temp var word ' Storage for temperature
T VAR WORD
DQ var PORTd.4 ' Alias DS1820 data pin
DQ_DIR var TRISd.4 ' Alias DS1820 data direction pin
read_done var byte
Lastdata var word


TRISc = $00 ' Set segment pins to output
TRISd = $f0 ' Set digit pins to output
TrisB = $00
Portb = $00
portd = $ff

DEFINE HSER_RCSTA 90h
DEFINE HSER_TXSTA 24h
DEFINE HSER_SPBRG 12 ' 19200 Bauds ,4 m
'debug ====

' Mainloop to read the temperature and display on LCD


mainloop:
'goto display
'Goto mainloop

Gosub init1820 ' Init the DS1820

command = $cc ' Issue Skip ROM command
Gosub write1820

command = $44 ' Start temperature conversion
Gosub write1820

Pause 2000 ' Wait 2 seconds for conversion to complete

Gosub init1820 ' Do another init

command = $cc ' Issue Skip ROM command
Gosub write1820

command = $be ' Read the temperature
Gosub write1820
Gosub read1820


'Display the decimal temperature
'HSEROUT ["Temp = ",dec (temp>>1),".", dec (temp.0*5)," C",13,10]
'T = ((temp>> 1)*100)+((TEMP.0*5)*10)
'HSEROUT ["Temp = ",dec T ,13,10]
value = ((temp>> 1)*100)+((TEMP.0*5)*10)
GOTO DISPLAY
Goto mainloop ' Do it forever


' Initialize DS1820 and check for presence
init1820:
Low DQ ' Set the data pin low to init
Pauseus 500 ' Wait > 480us
DQ_DIR = 1 ' Release data pin (set to input for high)

Pauseus 100 ' Wait > 60us
If DQ = 1 Then
'Lcdout $fe, 1, "DS1820 not present"
Pause 500
Goto mainloop ' Try again
Endif
Pauseus 400 ' Wait for end of presence pulse
Return


' Write "command" byte to the DS1820
write1820:
For i = 1 to 8 ' 8 bits to a byte
If command.0 = 0 Then
Gosub write0 ' Write a 0 bit
Else
Gosub write1 ' Write a 1 bit
Endif
command = command >> 1 ' Shift to next bit
Next i
Return

' Write a 0 bit to the DS1820
write0:
Low DQ
Pauseus 60 ' Low for > 60us for 0
DQ_DIR = 1 ' Release data pin (set to input for high)
Return

' Write a 1 bit to the DS1820
write1:
Low DQ ' Low for < 15us for 1
@ nop ' Delay 1us at 4MHz
DQ_DIR = 1 ' Release data pin (set to input for high)
Pauseus 60 ' Use up rest of time slot
Return


' Read temperature from the DS1820
read1820:
For i = 1 to 16 ' 16 bits to a word
temp = temp >> 1 ' Shift down bits
Gosub readbit ' Get the bit to the top of temp
Next i
Return

' Read a bit from the DS1820
readbit:
temp.15 = 1 ' Preset read bit to 1
Low DQ ' Start the time slot
@ nop ' Delay 1us at 4MHz
DQ_DIR = 1 ' Release data pin (set to input for high)
If DQ = 0 Then
temp.15 = 0 ' Set bit to 0
Endif
Pauseus 60 ' Wait out rest of time slot
Return
'================== 7 seg ment display ==============================
display:
'value = ((temp>> 1)*100)+((TEMP.0*5)*10)

PORTC = $39
LOW DIGITS.0
PAUSEUS 1500
PORTC = $0

'value = 125
For i = 1 To 4 ' Loop through 4 digits

n = Value Dig i ' Get digit to display

' Gosub display1 ' Display the value
Digits = $ff

Lookup n, [$3F, $06, $5B, $4F, $66, $6D, $7D, $07, $7F, $6F,_
$77, $7C, $39, $5E, $79, $71, $0FF], Segments

If i = 2 then segments = segments + 128 'Digit 2 show dot

Digits = ~Dcd i

NEXT I
goto mainloop
End

[sayzer]

If you have more then 2ms pause in total during the whole process, you will see blinking.

Have your calculator and start adding your pauses.
See what the total is.

Also, remove any repeat routines if any.

I have no time to check your code.

Why don't you use an easier DS1820 code by the way?


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[chai98a]

Hi sayzer thank you we done after try remove 2 ms out.


Buy the way we will post this code in exampls code for share with other peple