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sensor.thermocouple.max31856.spin
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sensor.thermocouple.max31856.spin
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{
----------------------------------------------------------------------------------------------------
Filename: sensor.thermocouple.max31856.spin
Description: Driver for the MAX31856 thermocouple amplifier
Author: Jesse Burt
Started: Sep 30, 2018
Updated: Sep 6, 2024
Copyright (c) 2024 - See end of file for terms of use.
----------------------------------------------------------------------------------------------------
}
#define HAS_COLDJUNC
#define HAS_THERMCPL
#include "sensor.temp.common.spinh"
CON
{ default I/O settings; these can be overridden in the parent object }
CS = 0
SCK = 1
MOSI = 2
MISO = 3
SPI_FREQ = 1_000_000
' Sensor resolution (deg C per LSB, scaled up)
' TC_RES = 0_0078125 ' 0.0078125 * 10_000_000
TC_RES = 0_00781 ' 0.00781 * 100_000
CJ_RES = 0_15625 ' 0.15625 * 100_000
' Operating modes
SINGLE = 0
CONT = 1
' Thermocouple types
TYPE_B = %0000
TYPE_E = %0001
TYPE_J = %0010
TYPE_K = %0011
TYPE_N = %0100
TYPE_R = %0101
TYPE_S = %0110
TYPE_T = %0111
VOLTMODE_GAIN8 = %1000
VOLTMODE_GAIN32 = %1100
' Interrupt mask bits (OR together any combination for use with int_mask())
CJ_HIGH = 1 << core.CJ_HIGH
CJ_LOW = 1 << core.CJ_LOW
TC_HIGH = 1 << core.TC_HIGH
TC_LOW = 1 << core.TC_LOW
OV_UV = 1 << core.OV_UV
OPEN = 1 << core.OPEN
' Temperature scales
C = 0
F = 1
VAR
byte _CS
OBJ
{ decide: Bytecode SPI engine, or PASM? Default is PASM if BC isn't specified }
#ifdef MAX31856_SPI_BC
spi: "com.spi.25khz.nocog" ' BC SPI engine
#else
spi: "com.spi.1mhz" ' PASM SPI engine
#endif
core: "core.con.max31856" ' HW-specific constants
PUB null()
' This is not a top-level object
PUB start(): status
' Start the driver using default I/O settings
return startx(CS, SCK, MOSI, MISO)
PUB startx(CS_PIN, SCK_PIN, SDI_PIN, SDO_PIN): status
' Start the driver with custom I/O settings
' CS_PIN: Chip Select, 0..31
' SCK_PIN: Serial Clock, 0..31
' MOSI_PIN: Master-Out Slave-In, 0..31
' MISO_PIN: Master-In Slave-Out, 0..31
' Returns:
' cog ID+1 of SPI engine on success (= calling cog ID+1, if the bytecode SPI engine is used)
' 0 on failure
if ( lookdown(CS_PIN: 0..31) and lookdown(SCK_PIN: 0..31) and ...
lookdown(SDI_PIN: 0..31) and lookdown(SDO_PIN: 0..31) )
if (status := spi.init(SCK_PIN, SDI_PIN, SDO_PIN, core.SPI_MODE))
_CS := CS_PIN
outa[_CS] := 1
dira[_CS] := 1
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
spi.deinit()
dira[_CS] := 0
_CS := 0
PUB cj_int_hi_thresh(): thresh
' Get Cold-Junction HIGH fault threshold
thresh := 0
readreg(core.CJHF, 1, @thresh)
return ~~thresh
PUB cj_int_set_hi_thresh(thresh)
' Set Cold-Junction HIGH fault threshold
' Valid values: -128..127 (default: 127; clamped to range)
thresh := -128 #> thresh <# 127
writereg(core.CJHF, 1, @thresh)
PUB cj_int_lo_thresh(): thresh
' Set Cold-Junction LOW fault threshold
' Valid values: -128..127 (default: -64)
' Any other value polls the chip and returns the current setting
thresh := 0
readreg(core.CJLF, 1, @thresh)
return ~~thresh
PUB cj_int_set_lo_thresh(thresh)
' Set Cold-Junction LOW fault threshold
' Valid values: -128..127 (default: -64; clamped to range)
thresh := -128 #> thresh <# 127
writereg(core.CJLF, 1, @thresh)
PUB cj_sensor_ena(state=-2): curr_state
' Enable the on-chip Cold-Junction temperature sensor
' Valid values: *TRUE (-1 or 1), FALSE
' Any other value polls the chip and returns the current setting
curr_state := 0
readreg(core.CR0, 1, @curr_state)
case ||(state)
0, 1:
state := (||(state) ^ 1) << core.CJ ' logic is inverted in the reg
state := ((curr_state & core.CJ_MASK) | state)
writereg(core.CR0, 1, @state)
other: ' so flip the bit
return (((curr_state >> core.CJ) & 1) ^ 1) == 1
PUB cj_word2temp(cj_word): temp
' Convert cold-junction ADC word to temperature, in hundredths of a degree
' in chosen scale
temp := (cj_word * CJ_RES) / 10_000
case _temp_scale
C:
F:
temp := ((temp * 90) / 50) + 32_00
PUB cj_bias(offset=negx): curr_offs
' Set Cold-Junction temperature sensor offset, in ten-thousandths of a degree C
' Valid values: -8_0000..7_9375 (default: 0)
' Any other value polls the chip and returns the current setting
case offset
-8_0000..7_9375:
offset /= 0_0625
writereg(core.CJTO, 1, @offset)
other:
curr_offs := 0
readreg(core.CJTO, 1, @curr_offs)
return (~curr_offs * 0_0625)
PUB cj_data(): cj_word
' Read cold-junction data
' Returns: s16
cj_word := 0
readreg(core.CJTH, 2, @cj_word)
~~cj_word ' extend sign from bit 15
cj_word ~>= 2 ' right-justify, keeping sign
' (ADC word is left-justified)
PUB int_clear() | tmp
' Clear fault status
' NOTE: This has no effect when int_latch_ena() is set to FALSE
tmp := 0
readreg(core.CR0, 1, @tmp)
tmp &= core.FAULTCLR_MASK
tmp := (tmp | (1 << core.FAULTCLR))
writereg(core.CR0, 1, @tmp)
PUB int_latch_ena(state=-2): curr_state
' Enable interrupt latching
' Valid values:
' *FALSE (0): fault flag will be asserted when fault condition is true, and will clear when
' the condition is no longer true, _with a 2deg C hysteresis._
' TRUE (1): fault flag will be asserted when fault condition is true, and will remain
' asserted until fault status is explicitly cleared with int_clear().
' NOTE: If the fault condition is still true when the status is cleared,
' the flag will be asserted again immediately.
' Any other value polls the chip and returns the current setting
curr_state := 0
readreg(core.CR0, 1, @curr_state)
case ||(state)
0, 1:
state := (state & 1) << core.FAULT
state := ((curr_state & core.FAULT_MASK) | state)
writereg(core.CR0, 1, @curr_state)
other:
return ((curr_state >> core.FAULT) & 1)
PUB int_mask(mask=-2): curr_mask
' Set interrupt mask (affects FAULT pin only)
' Valid values:
' Bits: 543210 (For each bit, 0: disable interrupt, 1: enable interrupt)
' Bit 5 Cold-junction interrupt HIGH threshold
' 4 Cold-junction interrupt LOW threshold
' 3 Thermocouple temperature interrupt HIGH threshold
' 2 Thermocouple temperature interrupt LOW threshold
' 1 Over-voltage or under-voltage input
' 0 Thermocouple open-circuit
' Example: %000010 would assert the /FAULT pin when an over-voltage or
' under-voltage condition is detected
' Any other value polls the chip and returns the current setting
' NOTE: FAULT pin is active low
case mask
%000000..%111111:
' the chip considers cleared bits as enabled and set bits
' as masked off, so invert the mask set by the user
' before actually writing it to the chip
mask := (mask ^ core.FAULTMASK_MASK)
mask |= (core.RSVD_BITS << core.RSVD)
writereg(core.FAULTMASK, 1, @mask)
other:
curr_mask := 0
readreg(core.FAULTMASK, 1, @curr_mask)
return (curr_mask ^ core.FAULTMASK_MASK)
PUB interrupt(): src
' Return interrupt status
' Returns: (for each individual bit)
' 0: No fault detected
' 1: Fault detected
'
' Bit 7 Cold-junction out of normal operating range
' 6 Thermcouple out of normal operating range
' 5 Cold-junction above HIGH temperature threshold
' 4 Cold-junction below LOW temperature threshold
' 3 Thermocouple temperature above HIGH temperature threshold
' 2 Thermocouple temperature below LOW temperature threshold
' 1 Over-voltage or Under-voltage
' 0 Thermocouple open-circuit
' NOTE: Asserted interrupts will always be flagged in this register,
' regardless of the set interrupt mask
' NOTE: FAULT pin is active low
src := 0
readreg(core.SR, 1, @src)
PUB measure() | tmp
' Perform single cold-junction and thermocouple conversion
' NOTE: Single conversion is performed only if opmode() is set to SINGLE
' Approximate conversion times:
' Filter Setting Time
' 60Hz 143ms
' 50Hz 169ms
' NOTE: Conversion times will be reduced by approximately 25ms if the
' cold-junction sensor is disabled
tmp := 0
readreg(core.CR0, 1, @tmp)
tmp &= core.ONESHOT_MASK
tmp := (tmp | (1 << core.ONESHOT))
writereg(core.CR0, 1, @tmp)
PUB notch_filt_freq(freq=-2): curr_freq | opmode_orig
' Select noise rejection filter frequency, in Hz
' Valid values: 50, 60*
' Any other value polls the chip and returns the current setting
' NOTE: The conversion mode will be temporarily set to Normally Off when changing notch filter
' settings per the MAX31856 datasheet, if it isn't already.
opmode_orig := opmode() ' remember the user's current operating mode
opmode(SINGLE)
curr_freq := 0
readreg(core.CR0, 1, @curr_freq)
case freq
50, 60:
freq := lookdownz(freq: 60, 50)
freq := ((curr_freq & core.NOTCHFILT_MASK) | freq)
writereg(core.CR0, 1, @freq)
opmode(opmode_orig) ' restore the user's operating mode
other:
opmode(opmode_orig)
curr_freq &= 1
return lookupz(curr_freq: 60, 50)
PUB oc_fault_test_time(time_ms=-2): curr_time 'XXX Note recommendations based on circuit design
' Sets open-circuit fault detection test time, in ms
' Valid values: 0 (disable fault detection), 10, 32, 100
' Any other value polls the chip and returns the current setting
curr_time := 0
readreg(core.CR0, 1, @curr_time)
case time_ms
0, 10, 32, 100:
time_ms := lookdownz(time_ms: 0, 10, 32, 100) << core.OCFAULT
time_ms := ((curr_time & core.OCFAULT_MASK) | time_ms)
writereg(core.CR0, 1, @time_ms)
other:
result := ((curr_time >> core.OCFAULT) & core.OCFAULT_BITS)
return lookupz(result: 0, 10, 32, 100)
PUB opmode(mode=-2): curr_mode
' Set operating mode
' Valid values:
' SINGLE (0): Single-shot/normally off
' CONT (1): Continuous conversion
' Any other value polls the chip and returns the current setting
' NOTE: In CONT mode, conversions occur continuously approx. every 100ms
curr_mode := 0
readreg(core.CR0, 1, @curr_mode)
case mode
SINGLE, CONT:
mode := (mode << core.CMODE)
mode := ((curr_mode & core.CMODE_MASK) | mode)
writereg(core.CR0, 1, @mode)
other:
return (curr_mode >> core.CMODE) & 1
PUB tc_smp_avg(samples=-2): curr_smp
' Set number of samples averaged during thermocouple conversion
' Valid values: *1, 2, 4, 8, 16
' Any other value polls the chip and returns the current setting
curr_smp := 0
readreg(core.CR1, 1, @curr_smp)
case samples
1, 2, 4, 8, 16:
samples := lookdownz(samples: 1, 2, 4, 8, 16) << core.AVGSEL
samples := ((curr_smp & core.AVGSEL_MASK) | samples)
writereg(core.CR1, 1, @samples)
other:
curr_smp := (curr_smp >> core.AVGSEL) & core.AVGSEL_BITS
return lookupz(curr_smp: 1, 2, 4, 8, 16)
PUB tc_data(): temp_word
' Read thermocouple data
' Returns: s19
temp_word := 0
readreg(core.LTCBH, 3, @temp_word)
temp_word <<= 8 ' extend sign from bit 23
temp_word ~>= 13 ' right-justify, keeping sign
' (ADC word is left-justified)
PUB tc_int_hi_thresh(): thresh
' Get thermocouple interrupt high threshold
thresh := 0
readreg(core.LTHFTH, 2, @thresh)
return ~~thresh
PUB tc_int_set_hi_thresh(thresh)
' Set thermocouple interrupt high threshold
' Valid values: -32768..32767 (default: 32767)
thresh := -32768 #> thresh <# 32767
writereg(core.LTHFTH, 2, @thresh)
PUB tc_int_lo_thresh(): thresh
' Set thermocouple interrupt low threshold
' Valid values: -32768..32767 (default: -32768)
' Any other value polls the chip and returns the current setting
thresh := 0
readreg(core.LTLFTH, 2, @thresh)
return ~~thresh
PUB tc_int_set_lo_thresh(thresh)
' Set thermocouple interrupt low threshold
' Valid values: -32768..32767 (default: -32768)
' Any other value polls the chip and returns the current setting
thresh := -32768 #> thresh <# 32767
writereg(core.LTLFTH, 2, @thresh)
PUB tc_type(type=-2): curr_type
' Set type of thermocouple
' Valid values: TYPE_B (0), TYPE_E (1), TYPE_J (2), *TYPE_K (3), TYPE_N (4),
' TYPE_R (5), TYPE_S (6), TYPE_T (7)
' Any other value polls the chip and returns the current setting
curr_type := 0
readreg(core.CR1, 1, @curr_type)
case type
TYPE_B, TYPE_E, TYPE_J, TYPE_K, TYPE_N, TYPE_R, TYPE_S, TYPE_T:
type := ((curr_type & core.TC_TYPE_MASK) | type)
writereg(core.CR1, 1, @type)
other:
return curr_type & core.TC_TYPE_BITS
PUB temp_word2deg = tc_word2temp
PUB tc_word2temp(tc_word): temp
' Convert thermocouple ADC word to temperature, in hundredths of a degree in chosen scale
temp := (tc_word * TC_RES) / 1000
case _temp_scale
C:
F:
temp := ((temp * 90) / 50) + 32_00
PRI readreg(reg_nr, nr_bytes, ptr_buff) | tmp
' Read nr_bytes from device into ptr_buff
case reg_nr ' validate register
core.CR0..core.SR:
outa[_CS] := 0
spi.wr_byte(reg_nr) ' shift out reg number
spi.rdblock_msbf(ptr_buff, nr_bytes) ' then read data, MSByte-first
outa[_CS] := 1
other: ' invalid; return
return
PRI writereg(reg_nr, nr_bytes, ptr_buff) | tmp
' Write nr_bytes from ptr_buff to device
case reg_nr
core.CR0..core.CJTL:
reg_nr |= core.WRITE_REG ' OR reg_nr with $80 to write
outa[_CS] := 0
spi.wr_byte(reg_nr)
spi.wrblock_msbf(ptr_buff, nr_bytes)
outa[_CS] := 1
other:
return
DAT
{
Copyright 2024 Jesse Burt
Permission is hereby granted, free of charge, to any person obtaining a copy of this software and
associated documentation files (the "Software"), to deal in the Software without restriction,
including without limitation the rights to use, copy, modify, merge, publish, distribute,
sublicense, and/or sell copies of the Software, and to permit persons to whom the Software is
furnished to do so, subject to the following conditions:
The above copyright notice and this permission notice shall be included in all copies or
substantial portions of the Software.
THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT
NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM,
DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT
OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
}