import array
import gc
from micropython import const
SAMPLE_COUNT = const(32 * 24)
Vdd0 = const(3.3)
Ta0 = const(25)
Resolution_correction = const(1)
emissivity = const(1)
class MLX90640:
def __init__(self, i2c, addr=51):
self.i2c = i2c
self.addr = addr
self.in_buf = bytearray(SAMPLE_COUNT * 2)
self.out_buf = bytearray(SAMPLE_COUNT * 2)
self.Vdd = self._get_Vdd()
self.Ta = self._get_Ta()
self.Kgain = self._get_Kgain()
self.offsets = self._get_offsets()
gc.collect()
self.Kta = self._get_Kta()
gc.collect()
self.Kv = self._get_Kv()
self.CPcompensation = self._get_CPcompensation()
self._read_cp(init=True)
self.TGC = self._get_TGC()
self.Acomp = self._get_Acomp()
gc.collect()
self.Ksto2 = self._get_Ksto2()
self.Tar = self._get_Tar()
gc.collect()
def _read_reg16(self, reg):
buf = self.i2c.readfrom_mem(self.addr, reg, 2, addrsize=16)
return buf
def _get_Vdd(self):
b = self._read_reg16(0x2433)
Kvdd = b[0]
if Kvdd > 127:
Kvdd -= 256
Kvdd <<= 5
Vdd25 = ((b[1] - 256) << 5) - 8192
b = self._read_reg16(0x072A)
VDDpix = b[0] << 8 | b[1]
if VDDpix > 32767:
VDDpix -= 65536
return (Resolution_correction * VDDpix - Vdd25) / Kvdd + Vdd0
def _get_Ta(self):
b = self._read_reg16(0x2432)
Kvptat = b[0] >> 2
if Kvptat > 31:
Kvptat -= 64
Kvptat /= 4096
Ktptat = (b[0] & 0x03) << 8 | b[1]
if Ktptat > 511:
Ktptat -= 1024
Ktptat /= 8
dV = self.Vdd - Vdd0
b = self._read_reg16(0x2431)
Vptat25 = b[0] << 8 | b[1]
if Vptat25 > 32767:
Vptat25 -= 65536
b = self._read_reg16(0x0720)
Vptat = b[0] << 8 | b[1]
if Vptat > 32767:
Vptat -= 65536
b = self._read_reg16(0x0700)
Vbe = b[0] << 8 | b[1]
if Vbe > 32767:
Vbe -= 65536
b = self._read_reg16(0x2410)
ALPHAptat_ee = (b[0] & 0xF0) >> 4
ALPHAptat = (ALPHAptat_ee >> 2) + 8
Vptat_art = (Vptat << 18) / (Vptat * ALPHAptat + Vbe)
return (Vptat_art / (1 + Kvptat * dV) - Vptat25) / Ktptat + Ta0
def _get_Kgain(self):
b = self._read_reg16(0x2430)
Gain = b[0] << 8 | b[1]
if Gain > 32767:
Gain -= 65536
b = self._read_reg16(0x070A)
denom = b[0] << 8 | b[1]
if denom > 32767:
denom -= 65536
return Gain / denom
def _get_offsets(self):
b = self._read_reg16(0x2411)
Offsetavg = b[0] << 8 | b[1]
if Offsetavg > 32767:
Offsetavg -= 65536
b = self._read_reg16(0x2410)
OCCscalerow = b[0] & 0x0F
OCCscalecol = b[1] >> 4
OCCscaleremnant = b[1] & 0x0F
OCCrow = []
for i in range(6):
b = self._read_reg16(0x2412 + i)
occ = b[1] & 0x0F
if occ > 7:
occ -= 16
occ <<= OCCscalerow
OCCrow.append(occ)
occ = b[1] >> 4
if occ > 7:
occ -= 16
occ <<= OCCscalerow
OCCrow.append(occ)
occ = b[0] & 0x0F
if occ > 7:
occ -= 16
occ <<= OCCscalerow
OCCrow.append(occ)
occ = b[0] >> 4
if occ > 7:
occ -= 16
occ <<= OCCscalerow
OCCrow.append(occ)
OCCcol = []
for i in range(8):
b = self._read_reg16(0x2418 + i)
occ = b[1] & 0x0F
if occ > 7:
occ -= 16
occ <<= OCCscalecol
OCCcol.append(occ)
occ = b[1] >> 4
if occ > 7:
occ -= 16
occ <<= OCCscalecol
OCCcol.append(occ)
occ = b[0] & 0x0F
if occ > 7:
occ -= 16
occ <<= OCCscalecol
OCCcol.append(occ)
occ = b[0] >> 4
if occ > 7:
occ -= 16
occ <<= OCCscalecol
OCCcol.append(occ)
PIXosref = array.array('f')
for r in range(24):
for c in range(32):
b = self._read_reg16(0x2440 + r * 32 + c)
Offset = b[0] >> 2
if Offset > 31:
Offset -= 64
Offset <<= OCCscaleremnant
PIXosref.append(Offsetavg + OCCrow[r] + OCCcol[c] + Offset)
return PIXosref
def _get_Kta(self):
b = self._read_reg16(0x2436)
oo = b[0]
if oo > 127:
oo -= 256
eo = b[1]
if eo > 127:
eo -= 256
b = self._read_reg16(0x2437)
oe = b[0]
if oe > 127:
oe -= 256
ee = b[1]
if ee > 127:
ee -= 256
Ktaavg = [[oo, oe], [eo, ee]]
b = self._read_reg16(0x2438)
Ktascale1 = (b[1] >> 4) + 8
Ktascale2 = b[1] & 0x0F
denom = 2 ** Ktascale1
Kta = array.array('f')
for r in range(24):
for c in range(32):
b = self._read_reg16(0x2440 + r * 32 + c)
Kta_ee = (b[1] & 0x0E) >> 1
if Kta_ee > 3:
Kta_ee -= 8
Kta.append((Ktaavg[r%2][c%2] + (Kta_ee << Ktascale2)) / denom)
return Kta
def _get_Kv(self):
b = self._read_reg16(0x2438)
Kvscale = b[0] & 0x0F
denom = 2 ** Kvscale
b = self._read_reg16(0x2434)
oo = b[0] >> 4
if oo > 7:
oo -= 16
eo = b[0] & 0x0F
if eo > 7:
eo -= 16
oe = b[1] >> 4
if oe > 7:
oe -= 16
ee = b[1] & 0x0F
if ee > 7:
ee -= 16
return [[oo / denom, oe / denom], [eo / denom, ee / denom]]
def _get_CPcompensation(self):
b = self._read_reg16(0x243A)
Off_CPsubpage0 = (b[0] & 0x03) << 8 | b[1]
if Off_CPsubpage0 > 511:
Off_CPsubpage0 -= 1024
Off_CPsubpage1delta = b[0] >> 2
if Off_CPsubpage1delta > 31:
Off_CPsubpage1delta -= 64
Off_CPsubpage1 = Off_CPsubpage0 + Off_CPsubpage1delta
b = self._read_reg16(0x2438)
Ktascale1 = (b[1] >> 4) + 8
Kvscale = b[0] & 0x0F
b = self._read_reg16(0x243B)
Ktacp_ee = b[1]
if Ktacp_ee > 127:
Ktacp_ee -= 256
Kvcp_ee = b[0]
if Kvcp_ee > 127:
Kvcp_ee -= 256
Kta_cp = Ktacp_ee / (2 ** Ktascale1)
Kv_cp = Kvcp_ee / (2 ** Kvscale)
multiplier = (1 + Kta_cp * (self.Ta - Ta0)) * (1 + Kv_cp * (self.Vdd - Vdd0))
CPcompensation0 = Off_CPsubpage0 * multiplier
CPcompensation1 = Off_CPsubpage1 * multiplier
return CPcompensation0, CPcompensation1
def _get_TGC(self):
b = self._read_reg16(0x243C)
TGCee = b[1]
if TGCee > 127:
TGCee -= 256
return TGCee / 32
def _get_Acomp(self):
b = self._read_reg16(0x2420)
Ascale_cp = ((b[0] & 0xF0) >> 4) + 27
b = self._read_reg16(0x2439)
Acp_subpage_0 = ((b[0] & 0x03) << 8 | b[1]) / (2 ** Ascale_cp)
CP_P1_P0ratio = (b[0] & 0xFC) >> 2
if CP_P1_P0ratio > 31:
CP_P1_P0ratio -= 64
Acp_subpage_1 = Acp_subpage_0 * (1 + CP_P1_P0ratio / 128)
b = self._read_reg16(0x243C)
Ksta_ee = b[0]
if Ksta_ee > 127:
Ksta_ee -= 256
Ksta = Ksta_ee / 8192
b = self._read_reg16(0x2421)
Areference = b[0] << 8 | b[1]
b = self._read_reg16(0x2420)
Ascale = (b[0] >> 4) + 30
ACCscalerow = b[0] & 0x0F
ACCscalecol = b[1] >> 4
ACCscaleremnant = b[1] & 0x0F
ACCrow = []
for i in range(6):
b = self._read_reg16(0x2422 + i)
acc = b[1] & 0x0F
if acc > 7:
acc -= 16
acc <<= ACCscalerow
ACCrow.append(acc)
acc = b[1] >> 4
if acc > 7:
acc -= 16
acc <<= ACCscalerow
ACCrow.append(acc)
acc = b[0] & 0x0F
if acc > 7:
acc -= 16
acc <<= ACCscalerow
ACCrow.append(acc)
acc = b[0] >> 4
if acc > 7:
acc -= 16
acc <<= ACCscalerow
ACCrow.append(acc)
ACCcol = []
for i in range(8):
b = self._read_reg16(0x2428 + i)
acc = b[1] & 0x0F
if acc > 7:
acc -= 16
acc <<= ACCscalecol
ACCcol.append(acc)
acc = b[1] >> 4
if acc > 7:
acc -= 16
acc <<= ACCscalecol
ACCcol.append(acc)
acc = b[0] & 0x0F
if acc > 7:
acc -= 16
acc <<= ACCscalecol
ACCcol.append(acc)
acc = b[0] >> 4
if acc > 7:
acc -= 16
acc <<= ACCscalecol
ACCcol.append(acc)
denom = 2 ** Ascale
Acomp = array.array('f')
for r in range(24):
for c in range(32):
i = r * 32 + c
b = self._read_reg16(0x2440 + i)
Apixel = ((b[0] & 0x03) << 4) | (b[1] >> 4)
if Apixel > 31:
Apixel -= 64
Apixel <<= ACCscaleremnant
A = (Areference + ACCrow[r] + ACCcol[c] + Apixel) / denom
if i % 2:
Acomp.append((A - self.TGC * Acp_subpage_1) * (1 + Ksta * (self.Ta - Ta0)))
else:
Acomp.append((A - self.TGC * Acp_subpage_0) * (1 + Ksta * (self.Ta - Ta0)))
return Acomp
def _get_Ksto2(self):
b = self._read_reg16(0x243D)
Ksto2_ee = b[0]
if Ksto2_ee > 127:
Ksto2_ee -= 256
b = self._read_reg16(0x243F)
Kstoscale = (b[1] & 0x0F) + 8
return Ksto2_ee / 2 ** Kstoscale
def _get_Tar(self):
Tak4 = (self.Ta + 273.15) ** 4
Tr = self.Ta - 8
Trk4 = (Tr + 273.15) ** 4
return Trk4 - (Trk4 - Tak4) / emissivity
def _read_cp(self, init=False):
b = self._read_reg16(0x0708)
PIXgain_cp_sp0 = b[0] << 8 | b[1]
if PIXgain_cp_sp0 > 32767:
PIXgain_cp_sp0 -= 65536
PIXgain_cp_sp0 *= self.Kgain
b = self._read_reg16(0x0728)
PIXgain_cp_sp1 = b[0] << 8 | b[1]
if PIXgain_cp_sp1 > 32767:
PIXgain_cp_sp1 -= 65536
PIXgain_cp_sp1 *= self.Kgain
if init:
self.PIXgain_cp_sp0 = PIXgain_cp_sp0
self.PIXgain_cp_sp1 = PIXgain_cp_sp1
else:
self.PIXgain_cp_sp0 = 0.8 * self.PIXgain_cp_sp0 + 0.2 * PIXgain_cp_sp0
self.PIXgain_cp_sp1 = 0.8 * self.PIXgain_cp_sp1 + 0.2 * PIXgain_cp_sp1
PIXos_cp_sp0 = self.PIXgain_cp_sp0 - self.CPcompensation[0]
PIXos_cp_sp1 = self.PIXgain_cp_sp1 - self.CPcompensation[1]
return PIXos_cp_sp0, PIXos_cp_sp1
def read(self, fast=False):
in_buf = self.in_buf
out_buf = self.out_buf
Kgain = self.Kgain
offsets = self.offsets
Kta = self.Kta
Kv = self.Kv
Ksto2 = self.Ksto2
Acomp = self.Acomp
Tar = self.Tar
PIXos_cp_sp0, PIXos_cp_sp1 = self._read_cp()
PIXos_cp_sp0 *= self.TGC
PIXos_cp_sp1 *= self.TGC
dT = self.Ta - Ta0
dV = self.Vdd - Vdd0
self.i2c.readfrom_mem_into(self.addr, 0x0400, in_buf, addrsize=16)
for r in range(24):
for c in range(32):
i = r * 32 + c
raw = in_buf[i*2] << 8 | in_buf[i*2 + 1]
if raw > 32767:
raw -= 65536
# Gain compensation
out = raw * Kgain
if fast:
# Compensate offset only
out = out - offsets[i]
else:
# IR data compensation: offset, Vdd, Ta
out = out - offsets[i] * (1 + Kta[i] * dT) * (1 + Kv[r%2][c%2] * dV)
# IR data Emissivity compensation
out = out / emissivity
# IR data gradient compensation
if i % 2:
out = out - PIXos_cp_sp1
else:
out = out - PIXos_cp_sp0
# Normalizing to sensitivity and Calculating To for basic temperature range
Sx = Ksto2 * (Acomp[i] ** 3 * out + Acomp[i] ** 4 * Tar) ** 0.25
out = (out / (Acomp[i] * (1 - Ksto2 * 273.15) + Sx) + Tar) ** 0.25 - 273.15
# Convert to int with x10 multiplier
out = int(out * 10)
if out < 0:
out += 65536
out_buf[i*2] = out >> 8
out_buf[i*2 + 1] = out & 0xFF
def get_buf(self):
return self.out_buf
def get_temperature(self, x, y):
if 0 <= x < 32 and 0 <= y < 24:
i = y * 32 + x
return (self.out_buf[i*2] << 8 | self.out_buf[i*2 + 1]) / 10.0
else:
raise ValueError('Coordinates out of range')