New Tutorial! Build an IoT device with Super SIM and the Raspberry Pi Pico

tsmith

Just posted: a new guide to plugging a Raspberry Pi Pico-based IoT device — a Waveshare Pico SIM7080G Cat-M/NB-IoT cellular add-on board and Super SIM provide the connectivity — into the Internet.

It includes:

• A full application built in MicroPython.
• An MCP9808 temperature sensor as a data source.
• An HT16K33-based four-digit, seven-segment LED for visual output.
• Over-the-air device control and reporting via Super SIM SMS Commands.

Check it out over in the Twiio docs.

tsmith

Update FYI, all, I’ve done a little refactoring on the code, and clarified a couple of points about what portions of additional code need to be added.

tsmith

Here’s a little extra: some replacement code for the temperature reading function, process_command_tmp(). In addition to sending off an SMS with the data, the code below also displays the current celsius temperature reading on the LED (including the unit symbol):

def process_command_tmp():
    print("Sending a temperature reading")
    celsius_temp = "{:.2f}".format(sensor.read_temp())
    if send_at("AT+CMGS=\"000\"", ">"):
        # '>' is the prompt sent by the modem to signal that
        # it's waiting to receive the message text.
        # 'chr(26)' is the code for ctrl-z, which the modem
        # uses as an end-of-message marker
        r = send_at_get_resp(celsius_temp + chr(26))
    # Display the temperature on the LED
    digit = 0
    previous_char = ""
    for temp_char in celsius_temp:
        if temp_char == "." and 0 < digit < 3:
            # Set the decimal point -- but only if we're not
            # at the last digit to be shown
            display.set_character(previous_char, digit - 1, True)
        else:
            # Set the current digit (a minus sign or a number)
            display.set_character(temp_char, digit)
            previous_char = temp_char
            digit += 1
        if digit == 3: break
    # Add a final 'c' and update the display
    display.set_character("c", 3).update()

If you prefer a capital C for Celsius, change the last line to:

display.set_glyph(0x39, 3).update()

The comments in the main code will show where the 0x39 comes from.