DS1820 - Help I'm rusty !

OK, just received some extra goodies for my easyPIC5 board, one of which is a DS1820 temp sensor. I've used Bruce's example as a starting point and edited it to work with the 2 x 16 LCD on the EasyPIC5 board, but I don't get anything displayed on the screen.

Its been a while since I did any programming, so I'm a tad rusty, Can someone give me some direction. Here are the main points:

16F887 running with 20Mhz
DS1820 output set to RA5
LCD on portB as per the user manual

Code:

TRISA=%11111111 ' set PORTA as all input TRISB=%00000000 ' set PORTB as all output DEFINE OSC 20 DEFINE LCD_DREG PORTB ' LCD data port DEFINE LCD_DBIT 0 ' LCD data starting bit 0 or 4 DEFINE LCD_RSREG PORTB ' LCD register select port DEFINE LCD_RSBIT 4 ' LCD register select bit DEFINE LCD_EREG PORTB ' LCD enable port DEFINE LCD_EBIT 5 ' LCD enable bit DEFINE LCD_BITS 4 ' LCD bus size 4 or 8 DEFINE LCD_LINES 2 ' Number lines on LCD DEFINE LCD_COMMANDUS 2000 ' Command delay time in us DEFINE LCD_DATAUS 50 ' Data delay time in us Comm_Pin VAR PortA.5 ' One-wire Data-Pin "DQ" on PortC.0 Busy VAR BIT ' Busy Status-Bit TempC VAR WORD ' Temp in deg C TempF VAR WORD ' Temp in deg F Float VAR WORD ' Holds remainder for + temp C display Cold_Bit VAR R_Temp.Bit11 ' Sign-Bit for +/- Temp. 1 = Below 0 deg C Real_Cold CON 1 ' Define Real_Cold = 1 Deg CON 223 ' Data to display Deg ° symbol Sign VAR BYTE ' +/- sign for temp display Dummy VAR BYTE ' Dummy for Div32 Start_Convert: OWOUT Comm_Pin, 1, [$CC, $44] ' Skip ROM search & do temp conversion Wait_Up: OWIN Comm_Pin, 4, [Busy] ' Read busy-bit IF Busy = 0 THEN Wait_Up ' Still busy..?, Wait_Up..! OWOUT Comm_Pin, 1, [$CC, $BE] ' Skip ROM search & read scratchpad memory OWIN Comm_Pin, 2, [R_Temp.Lowbyte, R_Temp.Highbyte] ' Read two bytes / end comms GOSUB Convert_Temp GOTO Start_Convert Convert_Temp: ' +32.0 to +257 F IF Cold_Bit = Real_Cold THEN Yikes ' If Cold_Bit = 1, it's below "0" deg C Sign = "+" Dummy = 625 * R_Temp ' Multiply to load internal registers with 32-bit value TempC = DIV32 10 ' Use Div32 value to calculate precise deg C Dummy = 1125 * R_Temp TempF = DIV32 100 IF TempF >6795 THEN ' Over 99.5 deg F..? TempF = TempF + 3200 lcdout $FE, 1," TempF = ",Sign,DEC TempF DIG 4,_ DEC TempF DIG 3,DEC TempF DIG 2,".",DEC2 TempF,Deg,"F " ELSE TempF = TempF + 3200 LCDOUT $FE,$C0, " TempF = ",Sign,DEC TempF DIG 3,_ DEC TempF DIG 2,".",DEC2 TempF,Deg,"F " ENDIF TempC = (R_Temp & $0FF0) >> 4 ' Mask middle 8-bits, shift into lower byte Float = ((R_Temp.Lowbyte & $0F) * 625) ' Lower 4-bits of result * 625 RETURN Yikes: ' Display full range -C to -F conversion Sign = "-" ' Display - symbol for negative temp Dummy = 625 * ~R_Temp+1 ' Multiply to load internal registers with 32-bit value TempC = DIV32 10 ' Use Div32 value to calculate precise deg C TempF = ~R_Temp / 16 ' Begin conversion from -C to deg +/-F IF TempF >=18 THEN ' Check for -degrees F "-18 C = -0.4 F" TempF = ((((TempF + 50) * 9) /5) -122) ' -C to -F below -17 deg C lcdout $FE, 1," TempF = ",Sign, DEC TempF,Deg,"F " LCDOUT $FE,$C0, " TempC = ",Sign,DEC TempC DIG 4,_ DEC TempC DIG 3,".",DEC3 TempC,Deg,"C " ELSE ' Else result = +deg F TempF = ((((-TempF + 50) * 9) /5) -58) ' -C to +F below 32.0 deg F to -17 deg C lcdout $FE, 1, " TempF = ","+",DEC TempF,Deg,"F " LCDOUT $FE,$C0 , " TempC = ",Sign,DEC TempC DIG 4,_ DEC TempC DIG 3,".",DEC3 TempC,Deg,"C " ENDIF RETURN END

There are a few compiling errors,
Cold_Bit VAR R_Temp.Bit11 gives "a bad data type"
OWIN Comm_Pin, 2, [R_Temp.Lowbyte, R_Temp.Highbyte] gives "expected [" and "expected ]" even though the exist
and half a dozen "bad expressions"

The example was for a serial LCD, where as mine is a traditional parallel one in 4 bit mode, so I've tried to convert the example, but its not displaying anything, even though it was cut and pasted from a bit of code I wrote a year ago which worked (just changed portC to port B for the use on the development board)

I'm sure its missing something really obvious. Should I still configure the chip, or use the settings in the Flash2 programmer software.

TIA

Quote:

Cold_Bit VAR R_Temp.Bit11 gives "a bad data type"

Not seeing where R_Temp is declared!

Quote:

OWIN Comm_Pin, 2, [R_Temp.Lowbyte, R_Temp.Highbyte] gives "expected [" and "expected ]" even though the exist
and half a dozen "bad expressions"

Are you using PBP 2.50A? There was a bug in the OWIN/OWOUT that was addressed here on the forums awhile back. Might apply to you if using PBP2.50A, not sure if the A patch covered the bug or not.
http://www.picbasic.co.uk/forum/show...ighlight=2.50a

Thanks for the comments, I said i was rusty :)

Using a some what older version 2.47

Quote:

Originally Posted by malc-c

Using a some what older version 2.47

Then it's back to declaring R_Temp

Now we're getting somewhere

Ok, with a bit of head scratching I've managed to get the LCD to display some text, and then added an edited section of Bruce's code to get the DEC value of TEMPf displayed on the screen

Code:

ANSEL = 0 ANSELH = 0 DEFINE OSC 20 DEFINE LCD_DREG PORTB DEFINE LCD_DBIT 0 DEFINE LCD_RSREG PORTB DEFINE LCD_RSBIT 4 DEFINE LCD_EREG PORTB DEFINE LCD_EBIT 5 DEFINE LCD_BITS 4 DEFINE LCD_LINES 2 DEFINE LCD_COMMANDUS 1000 DEFINE LCD_DATAUS 100 Comm_Pin VAR PortA.5 ' One-wire Data-Pin "DQ" on PortA.5 Busy VAR BIT ' Busy Status-Bit R_Temp VAR WORD ' RAW Temperature readings TempC VAR WORD ' Temp in deg C TempF VAR WORD ' Temp in deg F Float VAR WORD ' Holds remainder for + temp C display Cold_Bit VAR R_Temp.Bit11' Sign-Bit for +/- Temp. 1 = Below 0 deg C Real_Cold CON 1 ' Define Real_Cold = 1 Sign VAR BYTE ' +/- sign for temp display Dummy VAR BYTE ' Dummy for Div32 Start_Convert: OWOUT Comm_Pin, 1, [$CC, $44] ' Skip ROM search & do temp conversion Wait_Up: OWIN Comm_Pin, 4, [Busy] ' Read busy-bit IF Busy = 0 THEN Wait_Up ' Still busy..?, Wait_Up..! OWOUT Comm_Pin, 1, [$CC, $BE] ' Skip ROM search & read scratchpad memory OWIN Comm_Pin, 2, [R_Temp.Lowbyte, R_Temp.Highbyte] ' Read two bytes / end comms GOSUB Convert_Temp GOTO Start_Convert Convert_Temp: ' +32.0 to +257 F Sign = "+" Dummy = 625 * R_Temp ' Multiply to load internal registers with 32-bit value TempC = DIV32 10 ' Use Div32 value to calculate precise deg C Dummy = 1125 * R_Temp TempF = DIV32 100 IF TempF >6795 THEN ' Over 99.5 deg F..? TempF = TempF + 3200 lcdout $FE,1," Temp F = ",Sign,DEC TempF ELSE TempF = TempF + 3200 LCDOUT $FE,1, " Temp F = ",Sign,DEC TempF ENDIF TempC = (R_Temp & $0FF0) >> 4 ' Mask middle 8-bits, shift into lower byte Float = ((R_Temp.Lowbyte & $0F) * 625) ' Lower 4-bits of result * 625 RETURN

The code compiles and loads OK, and I get the value (3199) shown on the screen, but seem to have a few niggles I can't workout what settings I need to change.

1) - if viewed at an angle, the display seems to be scanning (ie its similar to the effect when filming a TV and you get a black bar slowley moving over the picture)

2) - holding the DS1820 between fingers I would expect the value to change, but it doesn't

Any guidance would help

Cutting and pasting the following from Bruce's example gives a bad expression error at the line beginning DEC TempF DIG 3

Code:

lcdout $FE,1," TempF = ",Sign,DEC TempF DIG 4,_ DEC TempF DIG 3,DEC TempF DIG 2,".",DEC2 TempF,Deg,"F "

EDIT:
Resolved (sort of !)

Code:

lcdout $FE,1," TempF = ",Sign,DEC TempF DIG 4,DEC TempF DIG 3,DEC TempF DIG 2,".",DEC2 TempF,"F "

Gives TempF = +031.99 on the LCD. Seems it was the "Deg" statement that was causing the issue. More work to do to get it reading the correct temperature (ie drop the 0) and if I recal 32F is 0 C and its not that cold in here !!!

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Hi, Malc

... Just try this one !!!

Hits the 10000 characters ... so, no code window !!!

It's been written for EP5 and DS18B20 ( I suppose you have a 18B20 as the 1820 is off production - if real 1820, ... nothing to change !!! )

you just have to add the °C to °F feature ...

I won't do everything for you ... be serious !!! ( LoL )

Alain

LCDout

I have not used OW, but I can comment on the LCD Problem.
LCDOUT $FE,1 Clears the LCD Panel. So you are clearing the whole screen, every time it goes through the loop.

Depending on the speed of the loop, this can give issues like flashing display, flickering, or scanning that I have seen.

The way I do it, is a LCDOUT $fe,1 before the loop to clear the LCD... Then, to display the data...

Code:

lcdout $FE,$80," Temp F = ",Sign,DEC TempF," " ELSE TempF = TempF + 3200 LCDOUT $FE,$80, " Temp F = ",Sign,DEC TempF," "

Be sure to add some spaces onto the end of the displayed temp (" ") so that when it goes from 10 to 9 degrees... you don't end up with 90. It is messier to code this way, but will result in a 100% flicker-free LCD...

Only use $FE,1 to clear the entire screen when you have to.

Quote:

Originally Posted by davewanna

Be sure to add some spaces onto the end of the displayed temp (" ") so that when it goes from 10 to 9 degrees... you don't end up with 90. It is messier to code this way, but will result in a 100% flicker-free LCD...

Only use $FE,1 to clear the entire screen when you have to.

Hey, don't knock it, I'm not a perfectionist, if it gets the desired result then that is all that matters.

Alain, thanks for the code, I'll have a play later and see what I get

Alain, I had to make some changes to suit the 16F887 (it didn't like the config bits and turning off comparitors for some reason), but I get the following displayed on screen

-23tC 0.06 -28T

Followed by a scale on second line with a rocket under the - of -28 (if that makes sence)

However I still can't get any change by placing my warmed hands on the DS chip.

Is there any way to test the DS device as it doesn't seem to be doing anythig

sorry!!

Malc-c..

Not nocking it at all! I had the LCD in my main project working like this for ages. The way I do it now is harder to code, and to change.. Often after a code change I end up with stray characters stuck on the screen after it changes page. Have to put in " "s all over the place to make sure everything is erased. But I got sick of the missus saying "Why is the display flickering like that?" on my home-made climate control in the car.

I should rephrase to...
I only use $FE,1 to clear the entire screen when I have to.

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Hi, Malc

If your sensor gives ONE TIME the correct temp ...

it is obvious ... you forgot to close the never-ending measuring Loop ... ( Mr de la Pallice )

....

Did you modify the program ??? ( else than just config bits, Osc speed ... etc )

-23tC 0.06 -28T

This should tell your DS 1820 is in a freezer ...

is it the truth ???

I will do a test ( must solder a dedicated cable ) to see if I can have a delicious ice-cream ...

the first line indicates : Bottom value of scale, actual temp, Top value of scale
second line is scale and index showing where you are between Bottm value and Top value ...

The "rocket" means the heating Output is ON ...

Alain

I give you the test results for negative temp ... keep on the line !

No, Alain, I'ts not that cold in here :)

I've done some searching on the net and tried the examples found at http://astrosurf.com/soubie/fichiers/RS_Test_DS1820.pbp and included the routines http://astrosurf.com/soubie/fichiers...0_Routines.pbp

The first thing I did was to leave the pin the DS is connected to as default and after loading the HEX the display did indeed state that the sendor was not detected. I then edited the code to point to pin RA5 as that is what I've set the jumper to on the EasyPIC5 board. I also remmed out all the lines not needed as per his comments, and remmed out the stored value and the gosubs for degrees Kelivin etc, so the display would simply show "Temp is" on line 1 and what the temp reads on line 2

On re-compiling / loading the HEX the display does indeed display a reading, -274.0 C

I've never worked with 1-wire devices, but assume that it gets interigated, sends a value which is stored in the PIC, which is then worked on with the maths to convert it to a temp reading? - I tried an experiment, I turned off the power and removed the DS sensor, and turned on the board, hoping that the display would tem ne no sensor detected. However it still read -274 C. Could it be that the 10K resistor between DQ and the 5v line is causing the PIC to read incorectly ???

Oh and just to confirm I have the DS device installed the right way round ;)

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Hi, Malc

LoL ...

as it was a Home thermostat, ... I was not in a hurry to deal with neg temps and had left them aside ...

Corrected now !

( was some fun to correctly display - 0.25 °C ... for info ! )

Alain

PS the DS is in my Deep freezer : - 20 °C .... pretty good !

re PS : Porta.0 and PORTA.1 have to be Hi Weak pulled up ...

Hi Alain, it's now getting hot in here !

I found another example on the net and pasted that into a new program that included my know LCD working code. The only switch activated on the board is SW9-7 for backlight.

Code:

temperature VAR WORD ' Temperature storage count_remain VAR BYTE ' Count remaining count_per_c VAR BYTE ' Count per degree C DQ VAR PORTA.5 ' One-wire data pin ' Define LCD registers and bits ;set PORTB as all output ANSEL = 0 ANSELH = 0 DEFINE OSC 20 DEFINE LCD_DREG PORTB DEFINE LCD_DBIT 0 DEFINE LCD_RSREG PORTB DEFINE LCD_RSBIT 4 DEFINE LCD_EREG PORTB DEFINE LCD_EBIT 5 DEFINE LCD_BITS 4 DEFINE LCD_LINES 2 DEFINE LCD_COMMANDUS 1000 DEFINE LCD_DATAUS 100 ADCON1 = 7 ' Set PORTA and PORTE to digital mainloop: OWOut DQ, 1, [$CC, $44] ' Start temperature conversion waitloop: OWIn DQ, 4, [count_remain] ' Check for still busy converting IF count_remain = 0 Then waitloop OWOut DQ, 1, [$CC, $BE] ' Read the temperature OWIn DQ, 0, [temperature.LOWBYTE, temperature.HIGHBYTE, Skip 4, count_remain, count_per_c] ' Calculate temperature in degrees C to 2 decimal places (not valid for negative temperature) temperature = (((temperature >> 1) * 100) - 25) + (((count_per_c - count_remain) * 100) / count_per_c) LCDOut $fe, 1, DEC (temperature / 100), ".", DEC2 temperature, " C" ' Calculate temperature in degrees F to 2 decimal places (not valid for negative temperature) temperature = (temperature */ 461) + 3200 LCDOut $fe, $c0, DEC (temperature / 100), ".", DEC2 temperature, " F" Pause 1000 ' Display about once a second GoTo mainloop ' Do it forever

The display now reads:
654.11 C
554.54 F

I'm just wondering if the DS device is faulty ?

I'll give your revised code a try later - I need a break !

Board and sensor is OK

Ok, I found the example on the EasyPIC5 CD (I know it should of been the first place to look, but as it was called one-wire and not temp sensor you can understand why I missed it - I said I was rusty !)

This works and gives a real temp of 25 degree C which rises when I touch the sensor. I apologise now as the following is not PBP - but hopefully someone can tell me why I was having so much trouble with PBP

Code:

' * ' * Project name ' Onewire_Test (Interfacing the DS18x20 temperature sensor - all versions) ' * Copyright ' (c) MikroElektronika, 2005-2008 ' * Description ' After reset, PIC reads temperature from the sensor and prints it on the Lcd. ' The display format of the temperature is 'xxx.xxxx°C'. To obtain correct ' results, the 18x20's temperature resolution has to be adjusted (constant ' TEMP_RESOLUTION) ' * Test configuration ' MCU PIC16F887 ' Dev.Board EasyPIC5 ' Oscillator HS, 08.0000 MHz ' Ext. Modules DS18x20 connected to RE2 pin, LCD_2x16 ' SW mikroC v8.0 ' * NOTES ' - Pull up and turning off diode on pin used for one wire bus may be required. ' * program Onewire_Test ' Set TEMP_RESOLUTION to the corresponding resolution of used DS18x20 sensor ' 18S20 9 (default setting can be 9,10,11,or 12) ' 18B20 12 const TEMP_RESOLUTION as byte = 9 dim text as string[8] temp as word sub procedure Display_Temperature(dim temp2write as Word) const RES_SHIFT as byte = TEMP_RESOLUTION - 8 dim temp_whole as byte temp_fraction as Word text = "000.0000" ' check if temperature is negative if (temp2write and $8000) = 0x8000 then text[0] = "-" temp2write = not temp2write + 1 end if ' extract temp_whole 0 temp_whole = temp2write >> RES_SHIFT ' convert temp_whole to characters if (temp_whole/100) then text[0] = temp_whole/100 + 48 end if text[1] = (temp_whole/10) mod 10 + 48 ' extract tens digit text[2] = temp_whole mod 10 + 48 ' extract ones digit ' extract temp_fraction and convert it to unsigned int temp_fraction = temp2write << (4-RES_SHIFT) temp_fraction = temp_fraction and $000F temp_fraction = temp_fraction * 625 ' convert temp_fraction to characters text[4] = temp_fraction/1000 + 48 ' extract thousands digit text[5] = (temp_fraction/100) mod 10 + 48 ' extract hundreds digit text[6] = (temp_fraction/10) mod 10 + 48 ' extract tens digit text[7] = temp_fraction mod 10 + 48 ' extract ones digit ' print temperature on LCD Lcd_Out(2, 5, text) end sub'~ main: ANSEL = 0 ' Configure AN pins as digital I/O ANSELH = 0 Lcd_Config(PORTB,3,2,1,0,PORTB,4,7,5) ' Lcd_Init_EP5, see Autocomplete Lcd_Cmd(LCD_CURSOR_OFF) Lcd_Out(1, 1, " Temperature ") ' Print degree character, 'C' for Centigrades Lcd_Chr(2,13,223) Lcd_Chr(2,14,"C") '--- main loop while TRUE '--- perform temperature reading Ow_Reset(PORTE,2) ' Onewire reset signal Ow_Write(PORTE,2,$CC) ' Issue command SKIP_ROM Ow_Write(PORTE,2,$44) ' Issue command CONVERT_T Delay_us(120) Ow_Reset(PORTE,2) Ow_Write(PORTE,2,$CC) ' Issue command SKIP_ROM Ow_Write(PORTE,2,$BE) ' Issue command READ_SCRATCHPAD temp = Ow_Read(PORTE,2) temp = (Ow_Read(PORTE,2) << 8) + temp '--- Format and display result on Lcd Display_Temperature(temp) Delay_ms(500) wend end.

Maybe its time to learn a new language ;)

Just some food for thought. This is the code I use for reading the DS18S20.

Code:

ReadDS18S20: owout sensor,1,[$CC, $44] ' Send Start Temperature Conversion command owout sensor,1,[$CC, $BE] ' Send Read Temperature command owin sensor,0,[STR dq\9] ' Retrieve all 9 bytes of data RawTemp.Byte0 = dq[0] RawTemp.byte1 = dq[1] if RawTemp.8 = 1 then ' Check if temperature is a negative reading SignC = Negative RawTemp.lowbyte = RawTemp.lowbyte ^ 255 ' Invert data else SignC = Positive endif dummy = RawTemp.0 ' Store the half degree indicator bit TempC = ((RawTemp.lowbyte) >> 1) * 100 ' Divide raw data by 2 to give real temperature TempC = TempC + (dummy * 50) ' Add the half degree is present if SignC = Negative then ' Only proceed if temperature is negative if TempC => 1770 then SignF = Negative TempF = (TempC + 5000) * 900 TempF = div32 500 TempF = TempF - 12200 return else SignF = Positive TempF = (TempC + 5000) * 900 TempF = div32 500 TempF = 12200 - TempF return endif endif SignF = Positive TempF = TempC * 18 / 10 + 3200 return

This is the code I use for the DS18B20. This one also includes the CRC calculation.

Code:

ReadDS18B20: low portb.7 : low portb.6 : low portb.5 pause 10 owout sensor,1,[$CC,$44] low RailPullUp pause 750 high RailPullUp owout sensor,1,[$CC,$BE] owin sensor,0,[STR dq\9] rawtemp.Byte0 = dq[0] rawtemp.Byte1 = dq[1] gosub getcrc if SensorError[sensor] = 1 and y < 3 then ReadDS18B20 gosub ConvertTemp if SensorError[sensor] = 1 then y = 0 TempC = 0 TempF = 3200 Signc = Positive SignF = Positive endif high portb.7 : high portb.6 : high portb.5 return ConvertTemp: if NegBit = 1 then BelowZero SignC = Positive SignF = Positive dummy = 625 * RawTemp TempC = DIV32 100 dummy = 0 dummy = 1125 * Rawtemp TempF = DIV32 100 TempF = TempF + 3200 return BelowZero: SignC = Negative dummy = 0 RawTemp.byte0 = RawTemp.byte0 ^ 255 RawTemp.Byte1 = RawTemp.byte1 ^ 255 dummy = 625 * RawTemp + 1 TempC = DIV32 100 TempF = (TempC + 5000) * 900 TempF = DIV32 500 if RawTemp >= 285 then TempF = TempF - 12199 SignF = Negative else TempF = 12199 - TempF SignF = Positive endif return '------------------------ Calculate the CRC from Byte 9 ------------------------ GetCRC: for x = 0 to 7 DataByte = dq[x] gosub CalcCRC next x if dq[8] <> CRCCalc then SensorError[sensor] = 1 y = y + 1 else SensorError[sensor] = 0 y = 0 endif CRCCalc = 0 return '--------------------- CRC Bit Calcuation Method ------------------------------- CalcCRC: for i = 0 to 7 DataBit = CRCCalc.0 ^ DataByte.0 DataByte = DataByte >> 1 if DataBit = 0 then Shift CRCCalc = CRCCalc ^ $18 Shift: CRCCalc = CRCCalc >> 1 CRCCalc.7 = DataBit next i return

"Maybe its time to learn a new language "

He he, don't let Alain hear you say that :-)
Pbp is somewhat dated, mE basic example is for the new DS 18S20, note the "S".
It has slightly reduced resolution from the DS 1820, or DS18B20 as it's now known, therefore the code to interrogate the device, and change the data into "English" :-) is different.
No, I don't have the solution, but at least I have a clear understanding of the problem, I think.

The DS1820 and the DS18S20 were software interchangeable as we started out using the 1820 and then switched to the 18S20 when we could not get the other. We changed nothing I our code from my memory though.

Quote:

Originally Posted by Copy'nPaste

"Maybe its time to learn a new language "

He he, don't let Alain hear you say that :-)

LOL - only kidding, it's taking me all these years to get my head pbp and I'm still getting it wrong ;) - Alain, I'm not going nowhere :)

@coke

Many thanks for posting your code - I'll give it a try now that I know the hardware is sound.