Al Semjonovs | fb8d8c5 | 2023-03-28 13:32:18 -0600 | [diff] [blame] | 1 | #!/usr/bin/env python3 |
| 2 | |
| 3 | # Copyright (c) 2023 Google LLC |
| 4 | # SPDX-License-Identifier: Apache-2.0 |
| 5 | |
| 6 | """ |
| 7 | Zephyr's NTC Thermistor DTS Table generator |
| 8 | ########################################### |
| 9 | |
Paweł Anikiel | 4b33f4f | 2023-08-04 10:36:35 +0000 | [diff] [blame] | 10 | This script can be used to generate an NTC thermistor DTS node with a |
| 11 | "zephyr,compensation-table" property. This uses the Beta Parameter Equation |
Al Semjonovs | fb8d8c5 | 2023-03-28 13:32:18 -0600 | [diff] [blame] | 12 | |
| 13 | https://devxplained.eu/en/blog/temperature-measurement-with-ntcs#beta-parameter-equation |
| 14 | |
| 15 | Look-up the following electrical characteristics in the thermistor's data sheet: |
| 16 | Nominal resistance (R25) - The thermistor's resistance measured at 25C |
| 17 | Beta value (25/85) - This is the resistance value at 25C and at 85C |
| 18 | |
| 19 | Usage:: |
| 20 | |
| 21 | python3 ntc_thermistor_table.py \ |
| 22 | -r25 10000 \ |
| 23 | -b 3974 > thermistor.dtsi |
| 24 | |
| 25 | """ |
| 26 | |
| 27 | import argparse |
| 28 | import os |
| 29 | import math |
| 30 | |
| 31 | def c_to_k(c: float): |
| 32 | """ Convert Celicius to Kelvin """ |
| 33 | return c + 273.15 |
| 34 | |
| 35 | def beta_equation_calc_resistance(r25, beta, temp_c): |
| 36 | t0_kelvin = c_to_k(25) |
| 37 | |
| 38 | exp = beta * ((1 / c_to_k(temp_c)) - (1 / t0_kelvin)) |
| 39 | resistance = r25 * math.exp(exp) |
| 40 | |
| 41 | return resistance |
| 42 | |
| 43 | |
| 44 | def main( |
| 45 | r25: float, beta: float, interval: int, temp_init: int, temp_final: int |
| 46 | ) -> None: |
| 47 | temps_range = range(temp_init, temp_final + interval - 1, interval) |
| 48 | |
| 49 | print(f"/* NTC Thermistor Table Generated with {os.path.basename(__file__)} */\n") |
Al Semjonovs | fb8d8c5 | 2023-03-28 13:32:18 -0600 | [diff] [blame] | 50 | print( |
Paweł Anikiel | 4b33f4f | 2023-08-04 10:36:35 +0000 | [diff] [blame] | 51 | f"thermistor_R25_{int(r25)}_B_{int(beta)}: thermistor-R25-{int(r25)}-B-{int(beta)} {{" |
Al Semjonovs | fb8d8c5 | 2023-03-28 13:32:18 -0600 | [diff] [blame] | 52 | ) |
Al Semjonovs | fb8d8c5 | 2023-03-28 13:32:18 -0600 | [diff] [blame] | 53 | |
| 54 | table = [] |
| 55 | for temp in temps_range: |
| 56 | resistance = beta_equation_calc_resistance(r25, beta, temp) |
| 57 | table.append(f"<({int(temp)}) {int(resistance)}>") |
| 58 | |
Paweł Anikiel | 4b33f4f | 2023-08-04 10:36:35 +0000 | [diff] [blame] | 59 | tbl_string = ',\n\t\t'.join(table) |
| 60 | print(f"\tzephyr,compensation-table = {tbl_string};") |
Al Semjonovs | fb8d8c5 | 2023-03-28 13:32:18 -0600 | [diff] [blame] | 61 | print(f"}};") |
| 62 | |
| 63 | |
| 64 | if __name__ == "__main__": |
| 65 | parser = argparse.ArgumentParser("NTC Thermistor generator", allow_abbrev=False) |
| 66 | parser.add_argument( |
| 67 | "-r25", type=float, required=True, help="Nominal resistance of thermistor" |
| 68 | ) |
| 69 | parser.add_argument( |
| 70 | "-b", "--beta", type=float, required=True, help="Beta(25/85) value" |
| 71 | ) |
| 72 | parser.add_argument( |
| 73 | "-i", |
| 74 | "--interval", |
| 75 | type=int, |
| 76 | required=False, |
| 77 | help="Generated table interval", |
| 78 | default=10, |
| 79 | ) |
| 80 | parser.add_argument( |
| 81 | "-ti", |
| 82 | type=int, |
| 83 | required=False, |
| 84 | help="First temperature", |
| 85 | default=-25, |
| 86 | ) |
| 87 | parser.add_argument( |
| 88 | "-tf", |
| 89 | type=int, |
| 90 | required=False, |
| 91 | help="Final temperature", |
| 92 | default=125, |
| 93 | ) |
| 94 | args = parser.parse_args() |
| 95 | |
| 96 | main(args.r25, args.beta, args.interval, args.ti, args.tf) |