diff options
Diffstat (limited to 'boiler-monster/original-pic-4.2.5/ds1820.asm')
| -rw-r--r-- | boiler-monster/original-pic-4.2.5/ds1820.asm | 198 |
1 files changed, 198 insertions, 0 deletions
diff --git a/boiler-monster/original-pic-4.2.5/ds1820.asm b/boiler-monster/original-pic-4.2.5/ds1820.asm new file mode 100644 index 0000000..b9b06c1 --- /dev/null +++ b/boiler-monster/original-pic-4.2.5/ds1820.asm @@ -0,0 +1,198 @@ + title "Outside sensor" + list p=16F88, b=8, r=dec + +#include "p16f88.inc" + errorlevel -302, -306 + +#define IOPORT PORTA,7 ;I/O port used for 1-wire line + +;1-wire ROM commands +#define READROM 0x33 +#define SKIPROM 0xCC +;1-wire FUNCTION commands +#define CONVERTT 0x44 +#define READSCRATCHPAD 0xBE +;1-wire family codes for supported temperature sensors +#define DS_FAM_DS18S20 0x10 +#define DS_FAM_DS18B20 0x28 +;Return codes, controlling when to perform the next step +#define DONE 0 ;Next step after one second +#define CONTINUE 1 ;Next step as soon as possible + + extern float1, float2, flags, temp, StoreOutTemp + + UDATA +sensorstage res 1 +#define ds18b20 sensorstage,7 +#define restart sensorstage,6 +lsbstorage res 1 + + +#define OutsideTemp flags,0 ;Keep in sync with gateway.asm +#define OutsideInvalid flags,1 ;Keep in sync with gateway.asm + + global Temperature +Temperature CODE +Temperature skpz ;Zero bit indicates no message in prog + goto Restart ;Sequence interrupted by OT message + btfsc restart + clrf sensorstage + ;Split up the temperature measurement into several short steps, + ;each less than 1ms. That way the main loop is allowed to run + ;frequently enough for it to be able to do all the necessary + ;processing in time, like clearing out the serial receive + ;register. + movlw high StageTable + movwf PCLATH + movfw sensorstage + andlw b'11111' + addlw low StageTable + skpnc + incf PCLATH,F + incf sensorstage,F ;Determine next step of the process + movwf PCL ;Jump to the current step +StageTable goto PresencePulse ;Step 0 - Transmit a reset pulse + goto SkipRom ;Step 1 - Address all devices on the bus + goto Measure ;Step 2 - Start a measurement + retlw DONE ;Step 3 - Allow time for measurement + goto PresencePulse ;Step 4 - Transmit a reset pulse + goto ReadRom ;Step 5 - Send Read ROM command + goto ReadFamily ;Step 6 - Read device family code + goto PresencePulse ;Step 7 - Transmit a reset pulse + goto SkipRom ;Step 8 - Address all devices + goto ReadCommand ;Step 9 - Send Read Scratchpad command + goto ReadLSB ;Step 10 - Read temperature value, LSB + goto ReadMSB ;Step 11 - Read temperature value, MSB + goto Restart ;Step 12 - Start over (never reached) + +PresencePulse bcf IOPORT ;Prepare the output latch + bsf STATUS,RP0 + bcf IOPORT ;Drive the output port low + call Delay480 ;Wait for the minimum reset duration + bsf STATUS,RP0 + bsf IOPORT ;Release the I/O port + bcf STATUS,RP0 + call Delay60 ;Allow the device time to respond + btfsc IOPORT ;Check the 1-wire line + goto NoDevice + call Delay240 ;Wait for the presence pulse to end + retlw CONTINUE +NoDevice bsf OutsideInvalid ;Outside temperature is not valid + goto Restart ;Start the sequence from the top + +Measure movlw CONVERTT ;Initiate temperature conversion + call WriteByte ;Send the command on the 1-wire bus + retlw DONE ;Give devices time to do the conversion + +ReadFamily call ReadByte ;Read family code from the 1-wire bus + movfw temp + sublw DS_FAM_DS18S20 ;Check if the sensor is a DS18S20 + skpnz + retlw CONTINUE ;Found a DS18S20 + movfw temp + sublw DS_FAM_DS18B20 ;Check if the sensor is a DS18B20 + skpz + goto NoDevice ;Not a supported temperature sensor + bsf ds18b20 ;Found a DS18B20 + retlw CONTINUE + +ReadCommand movlw READSCRATCHPAD ;The scratchpad contains the temerature + goto WriteByte ;Send the command on the 1-wire bus + +ReadLSB call ReadByte ;Read the first scratchpad byte + movfw temp + movwf lsbstorage ;Save the byte for later use + retlw CONTINUE + +ReadMSB call ReadByte ;Read the second scratchpad byte + btfsc ds18b20 ;Check which sensor type was found + goto HighPrecision ;A DS18B20 stores the value differently + rrf temp,W ;Sign of the temperature value + rrf lsbstorage,W ;Determine the full degrees + movwf float1 + clrf float2 + rrf float2,F ;Determine the half degrees + goto Success +HighPrecision swapf lsbstorage,W ;Get the 1/16 degrees in the high nibble + andlw b'11110000' + movwf float2 ;Store as outside temperture low byte + swapf temp,W ;Get the upper nibble of the degrees + andlw b'11110000' + movwf temp ;Save for later use + swapf lsbstorage,W + andlw b'1111' ;Get the lower nibble of the degrees + iorwf temp,W ;Combine with the saved upper nibble + movwf float1 ;Store as outside temperature high byte +Success bsf OutsideTemp ;Temperature measurement completed + bsf OutsideInvalid ;Invalid until validity is checked + xorlw 85 ;Test against powerup value + skpnz + goto Restart ;Not a valid measurement + lcall StoreOutTemp ;Store the measurement + retlw CONTINUE + +Restart bsf restart ;Don't clear sensorstage for debugging + retlw DONE + +Delay480 call Delay240 ;480 = 2 * 240 +Delay240 movlw 240 - 8 ;Value for 240uS delay (compensated) + goto Delay ;Wait for the specified amount of time +Delay60 movlw 60 - 6 ;Value for 60uS delay (compensated) +Delay bsf STATUS,RP0 ;Bank 1 + bcf PIE1,TMR2IE ;Disable interrupt from timer 2 + subwf PR2,W ;Calculate the start value + bcf STATUS,RP0 ;Bank 0 + addlw 10 ;Overhead for starting and stopping + movwf TMR2 ;Load the timer + bsf T2CON,TMR2ON ;Start timer 2 +WaitTimer2 btfss PIR1,TMR2IF ;Check if timer 2 expired + goto WaitTimer2 ;Wait some more + bcf T2CON,TMR2ON ;Stop timer 2 + bcf PIR1,TMR2IF ;Prevent unwanted interrupt + return + +Delay15 call Delay5 ;15 = 3 * 5 +Delay10 call Delay5 ;10 = 2 * 5 +Delay5 nop ;Wait 1 us + return ;Subroutine Call + Return = 2us + 2us + +ReadByte call ReadNibble ;Read 4 bits from 1-wire bus +ReadNibble call ReadBit ;Read 1 bit from 1-wire bus + call ReadBit ;Read 1 bit from 1-wire bus + call ReadBit ;Read 1 bit from 1-wire bus +ReadBit bcf IOPORT ;Prepare output latch + bsf STATUS,RP0 ;TRIS register is in Bank 1 + bcf IOPORT ;Drive the 1-wire line low + clrc ;Prepare carry while waiting + bsf IOPORT ;Release the 1-wire bus + bcf STATUS,RP0 ;Back to bank 0 + call Delay10 ;Allow device time to write the bit + btfsc IOPORT ;Read the 1-wire bus + setc ;Device wrote a "1" + rrf temp,F ;Shift bit into the result varaible + movlw 45 ;Maximum time a device drives the bus + call Delay ;Wait for the device to release the bus + return + +ReadRom movlw READROM ;Command to read a device's ROM code + goto WriteByte ;Send the command on the 1-wire bus +SkipRom movlw SKIPROM ;Address all devices on the 1-wire bus +WriteByte movwf temp ;Temporarily store the 1-wire command + call WriteNibble ;Write 4 bits to the 1-wire bus +WriteNibble call WriteBit ;Write 1 bit to the 1-wire bus + call WriteBit ;Write 1 bit to the 1-wire bus + call WriteBit ;Write 1 bit to the 1-wire bus +WriteBit rrf temp,F ;Set carry to least significant bit +WriteSlot bcf IOPORT ;Prepare the output latch + bsf STATUS,RP0 + bcf IOPORT ;Drive the 1-wire line low + skpnc ;Carry contains the bit to send + bsf IOPORT ;Release the 1-wire line + movlw 60 - 10 ;Value for 60uS delay (compensated) + call Delay ;Bit duration + bsf STATUS,RP0 ;Bank 1 + bsf IOPORT ;Float the 1-wire line, if necessary + bcf STATUS,RP0 ;Bank 0 + retlw CONTINUE + + end |