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sensor.pressure.mpl3115a2.spin
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{
--------------------------------------------
Filename: sensor.baro.mpl3115a2.spin
Author: Jesse Burt
Description: Driver for MPL3115A2 Pressure sensor with altimetry
Copyright (c) 2022
Started Feb 01, 2021
Updated Nov 26, 2022
See end of file for terms of use.
--------------------------------------------
}
#include "sensor.pressure.common.spinh"
#include "sensor.temp.common.spinh"
CON
SLAVE_WR = core#SLAVE_ADDR
SLAVE_RD = core#SLAVE_ADDR|1
DEF_SCL = 28
DEF_SDA = 29
DEF_HZ = 100_000
I2C_MAX_FREQ = core#I2C_MAX_FREQ
' Operating modes
SINGLE = 0
CONT = 1
' Barometer/altitude modes
BARO = 0
ALT = 1
OBJ
{ decide: Bytecode I2C engine, or PASM? Default is PASM if BC isn't specified }
#ifdef MPL3115A2_I2C_BC
i2c : "com.i2c.nocog" ' BC I2C engine
#else
i2c : "com.i2c" ' PASM I2C engine
#endif
core: "core.con.mpl3115a2" ' hw-specific low-level const's
time: "time" ' basic timing functions
u64 : "math.unsigned64" ' 64-bit unsigned int math
PUB null{}
' This is not a top-level object
PUB start{}: status
' Start using "standard" Propeller I2C pins and 100kHz
return startx(DEF_SCL, DEF_SDA, DEF_HZ)
PUB startx(SCL_PIN, SDA_PIN, I2C_HZ): status
' Start using custom IO pins and I2C bus frequency
if (lookdown(SCL_PIN: 0..31) and lookdown(SDA_PIN: 0..31) and I2C_HZ =< core#I2C_MAX_FREQ)
if (status := i2c.init(SCL_PIN, SDA_PIN, I2C_HZ))
time.usleep(core#T_POR) ' wait for device startup
if (i2c.present(SLAVE_WR)) ' test device bus presence
if (dev_id{} == core#DEVID_RESP)' validate device
return
' if this point is reached, something above failed
' Re-check I/O pin assignments, bus speed, connections, power
' Lastly - make sure you have at least one free core/cog
return FALSE
PUB stop{}
' Stop the driver
i2c.deinit{}
PUB defaults{}
' Set factory defaults
reset{}
PUB preset_active{}
' Like Defaults(), but
' * continuous sensor measurement
reset{}
opmode(CONT)
PUB alt_baro_mode(mode): curr_mode | opmd_orig
' Set sensor to altimeter or barometer mode
' Valid values:
' BARO (0): Sensor outputs barometric pressure data
' ALT (1): Sensor outputs altitude data
curr_mode := 0
readreg(core#CTRL_REG1, 1, @curr_mode)
case mode
BARO, ALT:
mode <<= core#ALT
other:
return ((curr_mode >> core#ALT) & 1)
opmd_orig := (curr_mode & 1) ' get current opmode
' must be in standby/SINGLE mode to set certain bits in this reg, so
' clear the opmode bit
mode := ((curr_mode & core#ALT_MASK & core#SBYB_MASK) | mode)
writereg(core#CTRL_REG1, 1, @mode)
if (opmd_orig == CONT) ' restore opmode, if it
opmode(opmd_orig) ' was CONT, previously
PUB alt_bias(offs): curr_offs
' Get altitude bias/offset
' Returns: meters
curr_offs := 0
readreg(core#OFF_H, 1, @curr_offs)
return ~curr_offs ' extend sign
PUB alt_data{}: alt_adc
' Read altimeter data
' NOTE: This is valid as altitude data _only_ if alt_baro_mode() is set to ALT (1)
alt_adc := 0
readreg(core#OUT_P_MSB, 3, @alt_adc)
PUB alt_set_bias(offs)
' Set altitude bias/offset, in meters
' Valid values: -128..127
offs := (-128 #> offs <# 127) ' LSB = 1m
writereg(core#OFF_H, 1, @offs)
PUB altitude{}: alt_cm
' Read altitude, in centimeters
' NOTE: This is valid as altitude data _only_ if alt_baro_mode() is set to ALT (1)
return alt_word2cm(alt_data{})
PUB alt_word2cm(alt_adc): alt_cm
' Convert altitude word to altitude, in centimeters
return u64.multdiv(alt_adc, 100_00, 65536)
PUB dev_id{}: id
' Read device identification
' Returns: $C4
readreg(core#WHO_AM_I, 1, @id)
PUB measure{} | tmp, meas
' Perform measurement
tmp := 0
readreg(core#CTRL_REG1, 1, @tmp)
case opmode(-2)
SINGLE:
tmp |= (1 << core#OST) ' bit auto-clears in SINGLE
writereg(core#CTRL_REG1, 1, @tmp) ' mode
CONT:
tmp |= (1 << core#OST)
writereg(core#CTRL_REG1, 1, @tmp)
tmp &= core#OST_MASK ' bit doesn't auto-clear in
writereg(core#CTRL_REG1, 1, @tmp) ' CONT mode; do it manually
PUB opmode(mode): curr_mode
' Set operating mode
' Valid values:
' SINGLE (0): Single-shot/standby
' CONT (1): Continuous measurement
curr_mode := 0
readreg(core#CTRL_REG1, 1, @curr_mode)
case mode
SINGLE, CONT:
other:
return (curr_mode & 1)
mode := ((curr_mode & core#SBYB_MASK) | mode)
writereg(core#CTRL_REG1, 1, @mode)
PUB oversampling(ratio): curr_ratio | opmd_orig
' Set output data ratio
' Valid values: 1, 2, 4, 8, 16, 32, 64, 128
' Any other value polls the chip and returns the current setting
curr_ratio := 0
readreg(core#CTRL_REG1, 1, @curr_ratio)
case ratio
1, 2, 4, 8, 16, 32, 64, 128:
ratio := lookdownz(ratio: 1, 2, 4, 8, 16, 32, 64, 128) << core#OS
other:
curr_ratio := (curr_ratio >> core#OS) & core#OS_BITS
return lookupz(curr_ratio: 1, 2, 4, 8, 16, 32, 64, 128)
opmd_orig := (curr_ratio & 1) ' get current opmode
' must be in standby/SINGLE mode to set certain bits in this reg, so
' clear the opmode bit
ratio := ((curr_ratio & core#OS_MASK & core#SBYB_MASK) | ratio)
writereg(core#CTRL_REG1, 1, @ratio)
if opmd_orig == CONT ' restore opmode, if it
opmode(opmd_orig) ' was CONT, previously
PUB press_bias{}: offs
' Get pressure bias/offset
' Returns: Pascals
offs := 0
readreg(core#OFF_P, 1, @offs)
return (~offs * 4) ' extend sign
PUB press_data{}: press_adc
' Read pressure data
' Returns: s20 (Q18.2 fixed-point)
' NOTE: This is valid as pressure data _only_ if alt_baro_mode() is
' set to BARO (0)
press_adc := 0
readreg(core#OUT_P_MSB, 3, @press_adc)
PUB press_data_rdy{}: flag
' dummy method
return true
PUB press_set_bias(offs)
' Set pressure bias/offset, in Pascals
' Valid values: -512..508 (clamped to range)
offs := (-512 #> offs <# 508) / 4 ' LSB = 4Pa
writereg(core#OFF_P, 1, @offs)
PUB press_word2pa(p_word): p_pa
' Convert pressure ADC word to pressure in Pascals
return ((p_word * 100) / 640)
PUB reset{} | tmp
' Reset the device
tmp := (1 << core#RST)
writereg(core#CTRL_REG1, 1, @tmp)
time.usleep(core#T_POR)
PUB sea_lvl_press{}: curr_press
' Get sea-level pressure for altitude calculations
' Returns: Pascals
curr_press := 0
readreg(core#BAR_IN_MSB, 2, @curr_press)
return curr_press << 1
PUB sea_lvl_set_press(press)
' Set sea-level pressure for altitude calculations, in Pascals
' Valid values: 0..131_070 (clamped to range)
press := (0 #> press <# 131_070) >> 1 ' LSB = 2Pa
writereg(core#BAR_IN_MSB, 2, @press)
PUB temp_bias{}: curr_offs
' Get temperature bias/offset
' Returns: ten-thousandths of a degree C
curr_offs := 0
readreg(core#OFF_T, 1, @curr_offs)
return (~curr_offs * 0_0625) ' extend sign
PUB temp_data{}: temp_adc
' Read temperature data
' Returns: s12 (Q8.4 fixed-point)
temp_adc := 0
readreg(core#OUT_T_MSB, 2, @temp_adc)
PUB temp_set_bias(offs)
' Set temperature bias/offset, in ten-thousandths of a degree C
offs := (-8_0000 #> offs <# 7_9375) / 0_0625' LSB = 0.0625C
writereg(core#OFF_T, 1, @offs)
PUB temp_word2deg(temp_word): temp
' Calculate temperature in degrees Celsius, given ADC word
' extend sign, chop off reserved LSBs, scale up to hundredths
' divide down to scale to degrees C
temp := (((~~temp_word) ~> 4) * 100) / 16
case _temp_scale
C:
return temp
F:
return ((temp * 9) / 5) + 32_00
other:
return FALSE
PRI readreg(reg_nr, nr_bytes, ptr_buff) | cmd_pkt
' Read nr_bytes from the device into ptr_buff
case reg_nr ' validate register num
core#STATUS..core#OFF_H:
cmd_pkt.byte[0] := SLAVE_WR
cmd_pkt.byte[1] := reg_nr
i2c.start{}
i2c.wrblock_lsbf(@cmd_pkt, 2)
i2c.start{}
i2c.wr_byte(SLAVE_RD)
' write MSByte to LSByte
i2c.rdblock_msbf(ptr_buff, nr_bytes, i2c#NAK)
i2c.stop{}
other: ' invalid reg_nr
return
PRI writereg(reg_nr, nr_bytes, ptr_buff) | cmd_pkt
' Write nr_bytes to the device from ptr_buff
case reg_nr
core#F_SETUP, core#PT_DATA_CFG..core#OFF_H:
cmd_pkt.byte[0] := SLAVE_WR
cmd_pkt.byte[1] := reg_nr
i2c.start{}
i2c.wrblock_lsbf(@cmd_pkt, 2)
' write MSByte to LSByte
i2c.wrblock_msbf(ptr_buff, nr_bytes)
i2c.stop{}
other:
return
DAT
{
Copyright 2022 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.
}