90 lines
2.7 KiB
Python
90 lines
2.7 KiB
Python
import numpy as np
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import matplotlib.pyplot as plt # Import matplotlib for plotting
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# Constants
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NTC_A1 = 0.003354016
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NTC_B1 = 0.000300131
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NTC_C1 = 5.08516E-06
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NTC_D1 = 2.18765E-07
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LOW_TEMP = 0
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HIGH_TEMP = 70
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N = 16 # Number of bits
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VREF = 3.0
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RESOLUTION = 0.01 # temp is in 0.01°C
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TEMP_CONV = 1/RESOLUTION
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CELSIUS_TO_KELVIN = 273.15
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def calc_temp_c(adc_voltage):
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log_ohms = np.log(1 / ((VREF / adc_voltage) - 1))
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temperature = 1 / (
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NTC_A1 +
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NTC_B1 * log_ohms +
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NTC_C1 * log_ohms**2 +
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NTC_D1 * log_ohms**3
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) - CELSIUS_TO_KELVIN
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return temperature
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def calc_voltage(adc_code):
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return adc_code * 150e-6 + 1.5 # Convert ADC ADBMS code to voltage
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def temp_table(adc_codes):
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temp = []
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for adc_code in adc_codes: # Signed 16-bit ADC range
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adc_voltage = calc_voltage(adc_code)
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try:
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temperature = calc_temp_c(adc_voltage)
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except (ValueError, ZeroDivisionError):
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temperature = None # Handle invalid calculations gracefully
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temp.append(temperature)
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return np.array(temp)
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def make_c_code(temp_values, low_t_adc, high_t_adc):
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# generate C code of an array and put into code.c file
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with open("tempTable.h", "w") as f:
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f.write("#include <stdint.h>\nconst uint16_t ADC2TEMP[] = {\n")
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for temp in temp_values:
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f.write(f" {(int)(temp*TEMP_CONV)}")
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if temp != temp_values[-1]:
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f.write(",")
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f.write("};")
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with open("tempCalc.c", "w") as f:
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f.write("""#include "tempTable.h"
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static inline uint16_t ntc_mv_to_celsius(int16_t adc) {
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// Out of bounds checking --> done by OV/UV setting of the BMS?
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if (adc < """ + str(int(low_t_adc)) + """ || adc > """ + str(int(high_t_adc)) + """) {
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return -1;
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}
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return ADC2TEMP[adc + """ + str(-int(low_t_adc)) + """];
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}
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""")
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if __name__ == "__main__":
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adc_codes = np.linspace(-2**(N - 1), 2**(N - 1) - 1, 2**N)
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temp_values = temp_table(adc_codes)
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bool_vec = (temp_values >= LOW_TEMP) & (temp_values <= HIGH_TEMP)
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low_t_adc = adc_codes[bool_vec][0]
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high_t_adc = adc_codes[bool_vec][-1]
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print(f"ADC code for {LOW_TEMP}°C: {low_t_adc}")
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print(f"ADC code for {HIGH_TEMP}°C: {high_t_adc}")
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plt.figure(figsize=(10, 6))
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plt.plot(adc_codes[bool_vec], temp_values[bool_vec], "b", label="0°C to 70°C")
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# plt.plot(adc_codes, temp_values, "r")
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# plt.xlim([-10000, 10000])
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plt.title("ADC Code to Temperature Conversion")
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plt.xlabel("ADC Code")
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plt.ylabel("Temperature (°C)")
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plt.grid(True)
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plt.legend()
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plt.show()
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make_c_code(temp_values[bool_vec], low_t_adc, high_t_adc)
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