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bkamen
Joined: 07 Jan 2004
Posts: 1615
Location: Central Illinois, USA
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 Posted: Mon Sep 14, 2009 11:05 pm |
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| Code: | //---------------------------------------------------------------------------
// CarayMonitor2.c
//
// This version uses a 12C672 instead. Plpllpllpllplpl
//
#include <12c672.h>
#rom 0x7ff = { 0x34A0 } // set RC calibration (A0=.995MHz, B0=1.05MHZ)
#fuses INTRC, PUT, NOWDT, NOPROTECT,NOMCLR
#use delay(clock=4000000)
#use rs232(xmit=PIN_A4, rcv=PIN_A5, baud=9600, bits=8, parity=n )
#include <ds1820.c>
// Store 8byte Serial Numbers + CRC in EEPROM
// [Famly] [LSB <- Serial Number -> MSB] [CRC]
int const serialArray[4][8]=
{{ 0x10, 0x5C, 0x7F, 0x15, 0x0, 0x0, 0x0, 0x13 }, // DS1820 - Thermometer
{ 0x10, 0xE5, 0x9F, 0x15, 0x0, 0x0, 0x0, 0x58 }, // DS1820 - Thermometer
{ 0x10, 0xF9, 0x89, 0x15, 0x0, 0x0, 0x0, 0x9E }, // DS1820 - Thermometer
{ 0x10, 0xF4, 0xA6, 0x15, 0x0, 0x0, 0x0, 0x43 }}; // DS1820 - Thermometer
static int temps[] = { 0x00, 0x00, 0x00, 0x00 };
static int adc[] = { 0x00, 0x00, 0x00, 0x00 };
// ===========================================================
//
void crlf() {
putc (13);
putc (10);
}
// ===========================================================
//
void main () {
int i,x;
float a,b;
setup_adc_ports( AN0_AN1_ANALOG );
setup_adc( ADC_CLOCK_INTERNAL );
while(1) {
putc(12);
puts("IBM 43p-240 (Type: 7043-240) SN:10-35065");
crlf();
puts("System Information:");
puts("=========================================");
puts("System Temperatures:");
printf("CPU-1: %03d%cC -- HeatSink-1: %03d%cC", temps[0], 39, temps[1], 39);
crlf();
printf("CPU-2: %03d%cC -- HeatSink-2: %03d%cC", temps[2], 39, temps[3], 39);
crlf();
crlf();
puts("System Voltages:");
a = adc[0] * .06188;
b = adc[1] * .0390625;
printf("+12: %06.2f (0x%02X)", a, adc[0] );
crlf();
printf(" +5: %05.2f (0x%02X)", b, adc[1] );
crlf();
for (i=0;i<=1;i++) {
set_adc_channel(i);
delay_ms(20);
adc[i] = read_adc();
}
for (i=0;i<=3;i++) {
for (x=0;x<=7;x++) {
serial[x] = serialArray[i][x];
}
ds_temp();
temps[i] = (scratchpad[1] * 0x80) + (scratchpad[0] >> 1);
}
delay_ms(2000);
}
}
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| Code: | //////////////////////////////////////////////////////////////////
// DS1820.C //
// Library for the Dallas 1820 Temperature Sensor //
// 12/22/97 Ben Kamen //
// //
// //
// dqlow() - Sets DS-1wire bus low //
// //
// dqhiz() - Sets DS-1wire bus high-Z //
// //
// ds_reset() - Sends Reset over DS-1wire bus //
// //
// ds_tx() - Sends byte over DS-1wire bus //
// //
// ds_rx() - Gets Byte from DS-1wire bus //
// //
// ds_temp() - Sends temp cmd and loads scratchpad[] //
// from device //
// //
// c_or_f(boolean degree) - returns long int of temp //
// degree= //
// 0=celcius //
// 1=farenheit //
// //
// //
//////////////////////////////////////////////////////////////////
//byte const DLY10 = 5; //10uS delay value for 10MHz (was 11 for 15uS)
//byte const DLY30 = 20; //30uS delay value for 10MHz (was 20)
//byte const DLY45 = 40; //45uS delay value for 10MHz
//byte const DLY60 = 60; //60uS delay value for 10MHz
byte const DLY10 = 2; //10uS delay value for 4MHz (was 11 for 15uS)
byte const DLY30 = 8; //30uS delay value for 4MHz (was 20)
byte const DLY45 = 16; //45uS delay value for 4MHz
byte const DLY60 = 24; //60uS delay value for 4MHz
//Common Equates for all Dallas 1-wire bus devices
byte const readrom = 0x33; // Read ROM Command
byte const matchrom = 0x55; // Match ROM Command
byte const skiprom = 0xCC; // Skip ROM Command
byte const skipod = 0x3C; // Skip ROM OverDrive Mode Command
byte const matchod = 0x69; // Match ROM OverDrive Mode Command
byte const searchrom = 0xF0; // Skip ROM Command
byte const searchalarm = 0xEC; // Skip ROM Command
// DS1820 Equates
byte const ds1820 = 0x10; // DS1820 Family ID Code
byte const tempconvert = 0x44; // Convert Command
byte const rscratch = 0xBE; // Read ScratchPad
byte const wscratch = 0x4E; // Write ScratchPad
byte const cscratch = 0x48; // Copy ScratchPad
byte const recalle = 0xB8; // Recall E2 into scratchpad
byte const rpower = 0xB4; // Read Power Supply Status
#byte port = 5 //Define your Port to use here.
byte const STATUS = 3; //Status Register
byte const RP0 = 5; //Register Page Bit
byte const C = 0; //Carry Bit
byte const TRIS = 0x85; //Define the Direction Control Register here.
byte const DSBIT = 2; //Define your Dallas Connection Pin Here - This is RA2
STATIC byte crc_byte; //Here's the CRC byte needed throughout
//Here's the Array for the Serial Number
// byte family;
// byte number[6];
// byte crc;
byte serial[8] = { 0, 0, 0, 0, 0, 0, 0, 0 };
// Here's the Array for the DS1820 Scratchpad.
// byte magn; //Temp Magnitude
// byte sign; //Temp Sign 0=+ve, 255=-ve
// byte tl; //User Temp Low Byte
// byte th; //User Temp High Byte
// byte unused[2]; //Reserved Register 4,5
// byte remain; //Count Remaining Register
// byte per_c; //Counts per 'C Register
// byte crc; //End CRC Byte
//
byte scratchpad[9];
///////////////////////////////////////////////////////////////
///////////////////////////////////////////////////////////////
// DQ LOW Routine. Set's DQ to output and then to
// Logic Low State
//
void dqlow() {
#asm
BCF PORT,DSBIT
BSF STATUS, RP0
BCF 0x85,DSBIT
BCF STATUS, RP0
#endasm
}
///////////////////////////////////////////////////////////////
// DQ HIZ Routine. Set's DQ to HI-Z State
//
void dqhiz () {
#asm
BSF STATUS, RP0
BSF 0x85,DSBIT
BCF STATUS, RP0
#endasm
}
///////////////////////////////////////////////////////////////
// DS_Reset - Sends Reset Pulse on the bus and then checks for a
// present pulse. Returns Boolean state of Pulse Detect
// 0 = Present, 1 = No Devices
//
boolean ds_reset () {
short i;
dqlow();
delay_us(600); // Pause 600uS to Reset Device
// The spec calls for 480uS MINIMUM
dqhiz();
delay_us(60); // Wait ~67us For Response Pulse
i = bit_test(port,dsbit);
while (!bit_test(port,dsbit)) { // Wait until it goes up again.
}
return i;
}
//////////////////////////////////////////////////////////////////////
// Here's the Transmit Byte Routine
// It sends out 1 byte at a time LSB first
// It's in Assembly due to the tight timing requirements
//
void ds_tx (int data) {
byte counter;
byte index;
#asm
MOVLW 8
MOVWF index
DSTXLP:
#endasm
dqlow();
#asm
MOVLW DLY10
MOVWF counter
LOOP1: DECFSZ counter,f
GOTO Loop1
RRF data, f
BTFSC STATUS, C
BSF PORT,DSBIT
MOVLW DLY45
MOVWF counter
LOOP2: DECFSZ counter,f
GOTO Loop2
#endasm
dqhiz();
// MOVLW DLY30
// MOVWF counter
//LOOP3: DECFSZ counter,f
// GOTO Loop3
#asm
DECFSZ index, f
GOTO DSTXLP
#endasm
}
//////////////////////////////////////////////////////////////////////
// Here's the Receive Byte Routine
// It pulls in 1 byte at a time LSB first
// It's in Assembly due to the tight timing requirements
//
byte ds_rx () {
byte index;
byte counter;
#asm
MOVLW 8
MOVWF index
CLRF _RETURN_
DSRXLP:
#endasm
dqlow();
#asm
MOVLW DLY10
MOVWF counter
LOOP1: DECFSZ counter,f
GOTO Loop1
#endasm
dqhiz();
#asm
NOP
MOVF PORT,W
ANDLW 1 << DSBIT
ADDLW 255
RRF _RETURN_, f
MOVLW DLY45
MOVWF counter
LOOP2: DECFSZ counter,f
GOTO Loop2
DECFSZ index, f
GOTO DSRXLP
#endasm
}
//////////////////////////////////////////////////////////////////////
// Here's the CRC Check Routine
// If ALL Received bytes from the 1820 pass through this routine,
// the result is Zer0. If all bytes but the CRC byte pass through,
// this routine passes back a number that should equal the CRC.
//
// Uses crc polynomial x8+x5+x4+1
//
// x8 -> x7 -> x6 -> x5 -> XOR -> x4 -> XOR -> x3 -> x2 -> x1
// ^ ^ ^ |
// | | | |
// +------------------------+------------+------ <- XOR <--+
// ^
// |
// Data-Bit
//
byte ds_crc (int data) {
byte bit_cnt;
byte tmp1;
for (bit_cnt = 8; bit_cnt != 0; bit_cnt--) {
tmp1 =(data ^ crc_byte) &1;
data >>=1; /* shift right one bit */
crc_byte >>=1; /* shift right one bit */
if (tmp1 !=0)
crc_byte ^=0x8c; /* x8+x5+x4+1 shifted one bit right */
}
return (crc_byte);
}
//////////////////////////////////////////////////////////////////////
// Here's the CRC-16 Check Routine
// This is used by the 1-wire devices that report 16bit CRC's back
// to the host when a READ takes place.
//
// Uses crc ploynomial x16+x15+x2+x1
//
//
//
// It's not here yet. Can you tell?? -Ben
//////////////////////////////////////////////////////////////////////
// Send_serialnum Routine
// Throws array serial[] onto bus
//
void send_serialnum() {
byte i;
ds_tx(matchrom);
delay_us(200);
for (i=0;i<=7;i++) {
ds_tx( serial[i] );
}
}
//////////////////////////////////////////////////////////////////////
// Here's the load_serialnum Routine
// Stuffs byte array serial[] into EEPROM offset by inbound
// "File Pointer"
//
void load_serialnum (int file) {
// byte i;
// byte tmp;
//
// file *= 8;
// for (i=0;i<=7;i++) {
// serial[i] = read_eeprom(file+i);
// }
}
//////////////////////////////////////////////////////////////////////
// Here's the Get Temp Routine
// This returns the entire scratchpad from the 1820 in
// variable scratchpad[]. It also rolls the received bytes through
// ds_crc() to get CRC value.
//
void ds_temp () {
byte i;
byte tmp;
crc_byte = 0; // clear CRC Byte
ds_reset(); // Reset Bus
delay_us(200); // Wait
send_serialnum(); // Send the Serial of device we want
ds_tx(tempconvert); // Send command to convert Temp
delay_ms(300); // Wait
ds_reset(); // Reset Bus
delay_us(200); // Wait
send_serialnum(); // Send the Serial of device we want
ds_tx(rscratch); // Get ScratchPad
for (i=0;i<=8;i++) { // Send it through CRC Routine
tmp = scratchpad[i] = ds_rx();
ds_crc(tmp);
}
}
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_________________
Dazed and confused? I don't think so. Just "plain lost" will do. :D |
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PCM programmer
Joined: 06 Sep 2003
Posts: 21708
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| Posted: Tue Sep 15, 2009 6:19 pm |
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I was able to make it work in parasite mode. I think the problem was
mainly in the timing of when the DQ pin should be set high. I will post
the list of modifications later, after I test it some more. |
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Kenny
Joined: 07 Sep 2003
Posts: 173
Location: Australia
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| Posted: Wed Sep 16, 2009 9:13 am |
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Edited:
Deleted post.
Testing showed that the delay at the end of write_bit() wasn't critical within the specified timeslot width.
Had to be a long way outside the specified range before it stopped working. |
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Guest
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| Posted: Thu Sep 17, 2009 6:00 am |
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PCM,
Many thanks, I'm eagerly awaiting your findings!
Joe |
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PCM programmer
Joined: 06 Sep 2003
Posts: 21708
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| Posted: Thu Sep 17, 2009 2:23 pm |
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This is basically what you need to do. Modify your write_byte() routine
so it has a parameter to tell it to optionally turn on Bus power at the
end of the transmission. Get rid of the separate write_bit() routine.
| Code: |
void write_byte(int8 val, int8 power_on)
{
int i;
for (i=0; i<8; i++)
{
output_low(DQ);
delay_us( 2 );
output_bit(DQ, shift_right(&val,1,0));
delay_us(60);
if((i == 7) && (power_on == 1))
{
output_high(DQ);
}
else
{
output_float(DQ);
delay_us( 2 );
}
}
} |
Then modify all the calls to write_byte() in your main code, so they
have the power on parameter. Then set it to turn power on after
the Temp Convert command is sent. Here's the relevant part:
| Code: |
while(1)
{
ow_reset();
write_byte(0xCC, 0); // Skip Rom command
write_byte(0x44, 1); // Temperature Convert command
delay_ms(750); // Max. time for conversion is 750mS
ow_reset();
write_byte(0xCC, 0); // Skip Rom command
write_byte(0xBE, 0); // Read scratch pad command
// Get the data bytes
for (i=0 ; i<8 ; i++)
{
scratch[i] = read_byte();
}
ow_reset(); |
Then it should work. Putting my finger on the DS18B20 chip causes
the temperature to rise:
| Quote: |
Temp: 25 C
Temp: 25 C
Temp: 25 C
Temp: 25 C
Temp: 25 C
Temp: 25 C
Temp: 26 C
Temp: 27 C
Temp: 27 C
Temp: 28 C
Temp: 28 C
Temp: 28 C
Temp: 29 C
Temp: 29 C
Temp: 28 C
Temp: 28 C
Temp: 28 C
Temp: 28 C
Temp: 28 C
Temp: 28 C
Temp: 28 C
Temp: 28 C
|
I didn't completely test this, and I didn't check the timing with a scope
or logic analyzer to see if it fits the data sheet's spec. You'll have to
do that. |
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Guest
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| Posted: Thu Sep 17, 2009 8:47 pm |
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Hi PCM,
That works - many thanks!
Interestingly, I experimented with a similar 'fix' that did not include the 'Power-on' flag. In retrospect that prevented my solution from working.
This experience has convinced me to get a scope, and I've got one on the way off eBay. When I get it, I'll look at the timing and verify that it's 'in spec.' For anyone following the thread, I'll report my findings sometime next week.
Thanks again for your interest, and your effort!
Joe |
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Guest
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| Posted: Thu Oct 01, 2009 1:16 pm |
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C-coders,
I'd like to use this code to read two different sensors on two separate input pins. To do this, I was thinking of replacing this line:
| Code: |
#define DQ PIN_A0 // One Wire Bus pin assignment
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with something like this
That would allow me to set DQ to any value from the .h file for my PIC and specify a different sensor using the same DS18B20 subroutines..... The problem is that it doesn't seem to work, and I'm not sure why. It compiles, but the temperature that is returned is always zero.
If this is not the proper way to specify different sensors, can someone recommend another method?
Cheers,
Greg |
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PCM programmer
Joined: 06 Sep 2003
Posts: 21708
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| Posted: Thu Oct 01, 2009 1:57 pm |
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This driver requires careful timing. The ASM code that CCS generates
to do pin i/o functions with a variable argument, is huge. It takes much
longer to execute than if a constant argument is used. You can see this
with a test program:
| Code: | #include <16F877.H>
#fuses XT, NOWDT, BROWNOUT, PUT, NOLVP
#use delay(clock=4000000)
//======================================
void main()
{
int8 pin = PIN_A0;
output_low(PIN_A0);
output_low(pin);
while(1);
} |
Here's the .LST file. Notice how it takes 4 instructions with a constant,
but a huge number with a variable argument. At 4 MHz, one instruction
takes 1 usec. With a variable argument, all these extra instructions
ruin the careful timing of the existing ds18b20 driver.
| Code: | .................... output_low(PIN_A0);
0030: BSF 03.5
0031: BCF 05.0
0032: BCF 03.5
0033: BCF 05.0
....................
.................... output_low(pin);
0034: MOVF 21,W
0035: MOVWF 22
0036: CLRF 23
0037: CLRF 25
0038: CLRF 24
0039: CALL 004
003A: MOVF 21,W
003B: MOVWF 22
003C: CLRF 23
003D: CLRF 25
003E: MOVLW 80
003F: MOVWF 24
0040: CALL 004
....................
// The routine at 0x0004:
0004: MOVF 22,W
0005: ANDLW 07
0006: MOVWF 77
0007: RRF 22,W
0008: MOVWF 78
0009: RRF 78,F
000A: RRF 78,F
000B: MOVLW 1F
000C: ANDWF 78,F
000D: MOVF 78,W
000E: ADDWF 24,W
000F: MOVWF 04
0010: BCF 03.7
0011: BTFSC 25.0
0012: BSF 03.7
0013: CLRF 78
0014: INCF 78,F
0015: INCF 77,F
0016: GOTO 018
0017: RLF 78,F
0018: DECFSZ 77,F
0019: GOTO 017
001A: MOVF 23,F
001B: BTFSC 03.2
001C: GOTO 020
001D: MOVF 78,W
001E: IORWF 00,F
001F: GOTO 023
0020: COMF 78,F
0021: MOVF 78,W
0022: ANDWF 00,F
0023: RETLW 00 |
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Guest
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| Posted: Thu Oct 01, 2009 2:10 pm |
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PCM,
OK, I understand the timing issues involved.
Do you have a recommendation for how I can read sensors on two separate pins using this code?
Thanks,
Greg |
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PCM programmer
Joined: 06 Sep 2003
Posts: 21708
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| Posted: Thu Oct 01, 2009 2:13 pm |
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Make a copy of the routines and give them new names. Use your other
pin number in the new routines. Call the new routines for the 2nd chip. |
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Guest
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| Posted: Thu Oct 01, 2009 2:47 pm |
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Hehe, I was afraid you were going to say that  !
I'm going to try a 20 MHz xtal first, and if that doesn't provide sufficient margin, I'll use separate code for each sensor!
Thanks,
Greg |
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Guest
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| Posted: Fri Oct 02, 2009 1:43 pm |
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Hi PCM,
I've been thinking about this issue, and I have a question. I understand that changing the DQ pin designation "on the fly" is time consuming from an instruction point-of-view. Obviously, something happens when the #Define DQ Pin_A0 is executed, and I'm not sure why I can't replicate that functionality to select another pin between readings of my two sensors. Yes, the readings themselves are time critical, but I've got tons of time available between readings. Isn't there some way to get the same effect as the #Define, to switch I/O pins during runtime? I'm not trying to be a pain, just to learn something here about how the compiler works, or its limitations.
Greg |
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Guest
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| Posted: Fri Oct 02, 2009 2:01 pm |
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Another thought is that there is some code written by Peter Anderson that is floating around that supports up to four sensors each on a separate pin. The only issue is that it's written for Port B. I looked at the code and it looks like I could change the PORTB calls to PORTA, and the TRISB to TRISA, and get the same functionality on Port A?
Greg |
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PCM programmer
Joined: 06 Sep 2003
Posts: 21708
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| Posted: Fri Oct 02, 2009 2:17 pm |
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| Quote: | | something happens when the #Define DQ Pin_A0 is executed, |
It happens at compile-time, not at run-time. At compile-time, the
compiler creates the machine code for the Hex file. It uses that
#define statement to put the correct numbers into the BSF and BCF
instructions in the machine code.
You could possibly use a switch-case statement. Re-write the routines
to accept a channel number (0 to 3), and inside each case, you could
do the i/o operation on the appropriate pin.
This is the Peter Anderson code. It might give you some ideas.
http://www.phanderson.com/PIC/PICC/CCS_PCM/ds1820.html |
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PCM programmer
Joined: 06 Sep 2003
Posts: 21708
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| Posted: Sun Mar 14, 2010 1:22 pm |
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Here's the complete test program for the ds18B20 in parasite-power
mode. This is the original poster's program, with the modifications
added, that I recommended in a post above. I'm posting the integrated
program because of a request.
| Code: |
#include <16F877.H>
#fuses XT, NOWDT, BROWNOUT, PUT, NOLVP
#use delay(clock=4000000)
#use rs232(baud=9600, xmit=PIN_C6, rcv=PIN_C7, ERRORS)
#define DQ PIN_C2
//-------------------------------------
void ow_reset(void)
{
output_low(DQ);
delay_us(500); // Min. 480uS
output_float(DQ);
delay_us(500); // Wait for end of timeslot
}
//-------------------------------------
// Read bit on one wire bus
int8 read_bit(void)
{
output_low(DQ);
delay_us(1);
output_float(DQ);
delay_us(12); // Read within 15uS from start of time slot
return(input(DQ));
}
//-------------------------------------
int8 read_byte(void)
{
int8 i;
int8 val = 0;
for(i=0 ; i<8 ; i++)
{
if(read_bit()) val |= (0x01 << i);
delay_us(120); // To finish time slot
}
return val;
}
//-------------------------------------
void write_byte(int8 val, int8 power_on)
{
int i;
for(i=0; i<8; i++)
{
output_low(DQ);
delay_us( 2 );
output_bit(DQ, shift_right(&val,1,0));
delay_us(60);
if((i == 7) && (power_on == 1))
{
output_high(DQ);
}
else
{
output_float(DQ);
delay_us( 2 );
}
}
}
//==========================================
void main(void)
{
int8 i;
signed int16 temperature;
int8 scratch[9];
output_float(DQ);
while(1)
{
ow_reset();
write_byte(0xCC, 0); // Skip Rom command
write_byte(0x44, 1); // Temperature Convert command
delay_ms(750); // Max. time for conversion is 750mS
ow_reset();
write_byte(0xCC, 0); // Skip Rom command
write_byte(0xBE, 0); // Read scratch pad command
// Get the data bytes
for(i=0; i < 8; i++)
{
scratch[i] = read_byte();
}
ow_reset();
temperature = (signed int16) make16(scratch[1],scratch[0]);
if(temperature >= 0)
temperature = (temperature + 8)/16;
else
temperature = (temperature - 8)/16;
printf("Temp: %4Ld C \n\r",temperature);
}
} |
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