Instrument telemetry API

This page lists the exact MicroPython functions your program calls to feed Snakie's live instruments — the Oscilloscope, Multimeter and Plotter. Telemetry means your board prints its readings and Snakie reads them from the serial link. (Serial = the USB cable your board talks over.)

For a friendly walkthrough of opening and using the instruments, see the Instruments guide. To build your first live graph step by step, try Plot a sensor.

Why telemetry?

Your program does a single, tiny print() for each reading. Snakie spots those special lines, sends each one to the right instrument, and hides them from the console. Because it is just printing, it is safe to call inside a fast while True: loop and it never interrupts your program.

Getting the library onto your board

The helpers live in one file, instruments.py. It is plain MicroPython with no extra parts needed, so it runs happily on a Raspberry Pi Pico.

1. Install it onto the board. Snakie can copy it for you with one click (see the Instruments guide), or you can drag instruments.py into the board's files next to your main.py.
2. Import it at the top of your program:

import instruments as inst

Core functions

These three are the ones you will use most. Call them again and again inside your loop.

Function	Feeds	What it does
inst.scope(value, ch="ch1")	Oscilloscope	Sends one waveform sample. Call it repeatedly to draw a moving line.
inst.meter(value, ch="adc0", unit="V")	Multimeter	Sends one reading. Snakie shows the latest value and tracks MIN / MAX / AVG.
inst.plot(*args, **kwargs)	Plotter	Sends one row of one or more series over time.

plot() is flexible. Plain numbers become numbered series, and name=value pairs become named ones — and you can mix them:

inst.plot(1, 2, 3)               # three numbered series
inst.plot(temp=21.4, light=80)   # two named series

What is ch?

ch (short for channel) is a label you pick, like "pwm" or "adc0". Snakie uses it to match a reading to the right instrument. If only one scope (or meter) is open, it receives your readings whatever the label — so the simple case just works.

Reader helpers

These read a hardware object for you, send the value, and also return it so you can use it in your code. (ADC = analog-to-digital converter, which measures a voltage. PWM = pulse-width modulation, a way to fake a varying output.)

Function	Feeds	Returns
inst.read_adc(adc, ch="adc0")	Multimeter	The voltage in volts. Reads adc.read_u16() and converts it (3.3 V reference, 16-bit).
inst.read_pwm(pwm, ch="pwm")	Oscilloscope	The duty as a fraction from 0 to 1 (pwm.duty_u16() / 65535).

Short examples

Oscilloscope — send a changing value each loop:

import time, math
import instruments as inst

t = 0
while True:
    inst.scope(math.sin(t))   # a smooth wave on the scope
    t += 0.1
    time.sleep(0.02)

Multimeter — measure a voltage on ADC pin 26:

import time
from machine import ADC
import instruments as inst

adc = ADC(26)
while True:
    inst.read_adc(adc, ch="adc0")   # shows volts on the meter
    time.sleep(0.1)

Plotter — graph two named series together:

import time
import instruments as inst

while True:
    inst.plot(temp=21.4, light=80)   # two lines on the plotter
    time.sleep(0.2)

Open the matching instrument in Snakie, run your program, and the readings appear live — no extra button needed.

What the wire lines look like

Under the hood, each helper does one print() of a single line that starts with the token SNK. You do not need to type these yourself, but it can help to know what Snakie is looking for:

SNK SCOPE <ch> <value>            # one oscilloscope sample
SNK METER <ch> <value> [<unit>]   # one meter reading (default unit "V")
SNK PLOT  <tok> [<tok> ...]       # one plotter row (numbers and/or name=value)

The SNK marker does three jobs: it routes the line to the correct instrument, hides it from the REPL console, and keeps the Plotter from mistaking scope or meter lines for graph data.

Tip

Because each helper is just a little text-formatting plus one print(), it is cheap and does not block. You can safely call it at speed inside a tight loop.

📸 Screenshot

Show: a running program printing telemetry while the Oscilloscope, Multimeter and Plotter update side by side.

The same library also includes helpers for robotics (orientation, distance, buttons, encoders, small displays) and an IDE-to-board control channel. Those are beyond this core reference — see the Instruments guide to explore them.