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# The same project on a Pico
Arduino · Real hardware
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## Today
**We are learning to** a Raspberry Pi Pico runs MicroPython. The ideas carry straight over (pins as outputs, reading a sensor, deciding, timing), but the words change, and so do two numbers: time.sleep takes seconds, and read_u16 gives 0 to 65535, not 0 to 1023.
- I can match Arduino C++ to MicroPython line by line.
- I can convert a threshold and a timing between the two.
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## Why it matters
> Many schools have Raspberry Pi Picos, and they run Python, which you may already know. Port the plant-water alarm. What changes, and what stays the same?
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💬 Discussion
## Predict
**On the Arduino, the alarm blinks at 300 or below (out of 1023). Can the Pico sketch keep the number 300?**
- No: the Pico can't read sensors
- No: read_u16 gives 0 to 65535, so 300 is almost bone dry
- Yes: the sensor is the same
- Yes: MicroPython converts it
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✅ Check
## What happened?
* No. The Pico's read_u16 gives 0 to 65535. 300 out of 1023 is about 29%, which is about 19200 out of 65535.
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✅ Check
## Match the lines
**Match each Arduino line to the MicroPython line that does the same job.**
| | |
|---|---|
| `pinMode(15, OUTPUT);` | A. level = sensor.read_u16() |
| `digitalWrite(15, HIGH);` | B. led = Pin(15, Pin.OUT) |
| `level = analogRead(A0);` | C. while True: |
| `delay(250);` | D. led.value(1) |
| `void loop() { … }` | E. time.sleep(0.25) |
* Answer: pinMode(15, OUTPUT); → B. led = Pin(15, Pin.OUT); digitalWrite(15, HIGH); → D. led.value(1); level = analogRead(A0); → A. level = sensor.read_u16(); delay(250); → E. time.sleep(0.25); void loop() { … } → C. while True:
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💬 Discussion
## Two numbers that change
$$\text{read: } 0 \ldots 1023 \to 0 \ldots 65535$$
1) $300 \div 1023 \approx 0.293$ — The threshold as a fraction of the range.
2) $0.293 \times 65535 \approx 19200$ — The same threshold on the Pico.
3) $\text{delay(250)} \to \text{time.sleep(0.25)}$ — Milliseconds to seconds: ÷ 1000.
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✅ Check
## Two numbers that change
**The Arduino threshold is 300 out of 1023. What is that out of 65535? (nearest hundred)**
* Answer: 19200
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✅ Check
## Find the mistake
**Sam's Pico port never blinks, and when Sam taps the sensor it stays on for minutes. Click the first line that goes wrong.**
```
1 from machine import Pin, ADC
2 import time
3 led = Pin(15, Pin.OUT)
4 sensor = ADC(26)
5 while True:
6 if sensor.read_u16() <= 300:
7 led.value(1)
8 time.sleep(250)
9 led.value(0)
10 time.sleep(250)
```
* Answer: line 6
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✍️ Activity
## Vary: put it together
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✍️ Activity
## Try it in Wokwi or on a Pico
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✅ Check
## Timing
**delay(1500) on the Arduino. What goes in time.sleep( ) on the Pico?**
* Answer: 1.5
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✅ Check
## What stayed
**Which part of the alarm needed no change at all?**
- The timing numbers
- The threshold number
- The idea: read, compare with a threshold, blink or stay off
- The pin numbers' names
* Answer: The idea: read, compare with a threshold, blink or stay off
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✍️ Activity
## Make: port the fridge alarm
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✅ Check
## Exit ticket
**Name the two numbers that must change when you port the alarm to the Pico, and how.**
* The threshold (scale from 0–1023 to 0–65535, × about 64) and the delays (milliseconds to seconds, ÷ 1000).