sensor.temperature.ds18b2x.spin2

{
----------------------------------------------------------------------------------------------------
    Filename:       sensor.temperature.ds18b2x.spin2
    Description:    Driver for the Dallas/Maxim DS18B2x-series temperature sensors
    Author:         Jesse Burt
    Started:        Feb 7, 2021
    Updated:        Oct 19, 2024
    Copyright (c) 2024 - See end of file for terms of use.
----------------------------------------------------------------------------------------------------
}

#include "sensor.temp.common.spin2h"            ' use code common to all temp sensor drivers

CON

    { default I/O settings; these can be overridden in the parent object }
    OW_PIN  = 0

    ' Operating modes
    ONE     = 0
    MULTI   = 1

    SN_LSB  = 0
    SN_MSB  = 7
    SPAD_LSB= 0
    SPAD_MSB= 8


OBJ

    core:   "core.con.ds18b2x"                  ' HW-specific constants
    ow:     "com.onewire"                       ' OneWire bus engine
    crc:    "math.crc"                          ' CRC routines


VAR

    long _sel_addr[2], _lastcrc_valid
    byte _opmode


PUB null()
' This is not a top-level object


PUB start(): status
' Start using default I/O settings
    return startx(OW_PIN)


PUB startx(DQ_PIN): status
' Start the driver with custom I/O settings
'   SCL_PIN:    OneWire data, 0..63
'   Returns:
'       cog ID+1 of OW engine on success
'       0 on failure
    if ( lookdown(DQ_PIN: 0..63) )
        if ( status := ow.init(DQ_PIN) )
            return
    ' if this point is reached, something above failed
    ' Double check I/O pin assignments, connections, power
    ' Lastly - make sure you have at least one free core/cog
    return FALSE


PUB stop()
' Stop the driver
    ow.deinit()
    longfill(@_sel_addr, 0, 3)
    _opmode := 0


PUB defaults()
' Factory default settings
    temp_adc_res(12)
    temp_scale(C)


PUB last_crc_valid(): v
' Flag indicating CRC of last data read from sensor was valid
'   Returns: TRUE (-1) or FALSE (0)
'   NOTE: CRC is calculated from entire DS18B20 scratchpad RAM
    return _lastcrc_valid


PUB opmode(mode): c
' Set operation mode
'   Valid values:
'       ONE (0): one connected device
'       MULTI (1): Multi-drop, for multiple connected devices
'   Any other value returns the current setting
    case mode
        ONE, MULTI:
            _opmode := mode
        other:
            return _opmode


PUB search(p_buff, nr_devs): n
' Search bus for devices and store their addresses into a buffer
'   NOTE: This buffer must be at least (8 * nr_devs) bytes
    return ow.search(ow.CHECK_CRC, nr_devs, p_buff)


PUB select(p_addr)
' Select device for subsequent operations
'   p_addr: pointer to buffer containing 64-bit ID
    longmove(@_sel_addr, p_addr, 2)


PUB serial_num(p_buff): i
' Read 64-bit serial number of device into buffer at ptr_buff
'   NOTE: Buffer at ptr_buff must be 8 bytes in length
'   NOTE: Includes family code (LSB) and CRC (MSB)
'   Returns: Flag indicating whether CRC is valid
    ow.reset()
    ow.wr_byte(ow.RD_ROM)
    ow.rd_addr(p_buff)
    return (crc.dallas_maxim_crc8(p_buff, 7) == byte[p_buff][SN_MSB])


PUB temp_adc_res(bits): c
' Set resolution of temperature readings, in bits
'   Valid values: 9..12
'   Any other value polls the chip and returns the current setting
    case bits
        9..12:
            bits := lookdownz(bits: 9..12) << core.R0
            poll_dev()
            ow.wr_byte(core.WR_SPAD)
            ow.wr_word($0000)                   ' skip over Th, Tl regs
            ow.wr_byte(bits)
            ow.reset()
        other:
            poll_dev()
            ow.wr_byte(core.RD_SPAD)
            ow.rd_long()                        ' skip over temperature, Th, Tl
            c := (ow.rd_byte() >> core.R0)
            return lookupz(c: 9..12)


PUB temp_data(): d | tmp[3], i
' Read temperature data
    d := 0
    poll_dev()

    ow.wr_byte(core.CONV_TEMP)
    repeat
    until ow.rd_bits(1)                  ' wait until measurement ready

    poll_dev()

    ow.wr_byte(core.RD_SPAD)
    repeat i from 0 to 8
        tmp.byte[i] := ow.rd_byte()

    d := tmp.word[0]
    _lastcrc_valid := (crc.dallas_maxim_crc8(@tmp, 8) == tmp.byte[SPAD_MSB])
    ow.reset()


PUB temp_word2deg(temp_word): t
' Convert temperature ADC word to temperature
'   Returns: temperature, in hundredths of a degree, in chosen scale
    t := (temp_word signx 15) * 5
    case _temp_scale
        C:
            return t
        F:
            return ((t * 9) / 5) + 32_00
        other:
            return t


PRI poll_dev()
' Poll a device
    ow.reset()
    case _opmode
        ONE:                                    ' match first device that
            ow.wr_byte(ow.SKIP_ROM)             '   responds
        MULTI:
            ow.wr_byte(ow.MATCH_ROM)            ' match a specific device
            ow.wr_addr(@_sel_addr)


DAT
{
Copyright 2024 Jesse Burt

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The above copyright notice and this permission notice shall be included in all copies or
substantial portions of the Software.

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}