journalisation.py
MicroPython exposes the internal flash as a filesystem: this script writes a temperature CSV there every 5 s, in append mode so data is never overwritten. The file is later retrieved like a USB stick.
Hardware
A generic RP2040 (dual Cortex-M0+) board programmed with MicroPython. No external part; the board flash is the storage (a few MB available).
Wiring
No wiring: internal readings only. Add a sensor (DHT, ADC) keeping the same line format.
How it works
open(FICHIER, "a") opens in append; each line holds seconds since boot and the temperature. os.stat()[6] gives the size to watch the fill-up.
Running it
Flash MicroPython via BOOTSEL (.uf2 file), then copy the script to the board drive. Check your board's user LED pin (often GP25) and adapt if needed.
Variants
Add rotation (rename journal.csv to journal-1.csv past 100 KB), or timestamp with an external RTC such as DS3231.
journalisation.py
# Journal CSV dans le systeme de fichiers interne (flash) de la carte.
import time
import os
import machine
FICHIER = "journal.csv"
ENTETE = "timestamp,temperature_c
"
def temperature():
adc = machine.ADC(4) # capteur thermique interne
v = adc.read_u16() * 3.3 / 65535.0
return 27.0 - (v - 0.706) / 0.001721
# Creer le fichier avec l'entete s'il n'existe pas.
if FICHIER not in os.listdir():
with open(FICHIER, "w") as f:
f.write(ENTETE)
print("Journalisation toutes les 5 s")
while True:
t = temperature()
horodatage = time.ticks_ms() // 1000
with open(FICHIER, "a") as f: # append : pas d'ecrasement
f.write("%d,%.2f
" % (horodatage, t))
taille = os.stat(FICHIER)[6]
print("+1 ligne (%d octets au total)" % taille)
time.sleep(5)
# Recuperer le CSV : ouvrir le lecteur de la carte ou "Thonny > Fichiers".