feat(examples): update dual Pico example to demonstrate bidirectional digital handshake
This commit is contained in:
David Montero Crespo
parent
2ac94aed24
commit
0a66c70512
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@ -2852,12 +2852,12 @@ void loop() {
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},
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{
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id: 'dual-pico-i2c-master-slave',
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title: '[2× Pico W] I²C Master/Slave LED Control',
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id: 'dual-pico-bidirectional-handshake',
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title: '[2× Pico W] Bidirectional Digital Handshake',
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description:
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'Pico A is the I²C master on Wire (GP4=SDA, GP5=SCL). It sends 1-byte commands (1=LED ON, 0=LED OFF) every second to Pico B at address 0x42. Pico B drives its built-in LED based on the command via Wire.onReceive.',
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'Two Picos signal each other over independent digital lines. Pico A drives GP15 (data) and watches GP14 (ack); Pico B reads GP15 and pulses GP14 on every transition to acknowledge. Each board\'s Serial Monitor logs every event, so you can see the round-trip on both sides.',
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category: 'communication',
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difficulty: 'intermediate',
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difficulty: 'beginner',
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boardFilter: 'raspberry-pi-pico',
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code: '',
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boards: [
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@ -2865,47 +2865,60 @@ void loop() {
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boardKind: 'pi-pico-w',
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x: 100,
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y: 120,
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code: `// Pico A — I²C master
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// Sends 1-byte commands to slave 0x42:
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// 0x01 → LED ON
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// 0x00 → LED OFF
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code: `// Pico A — sender + ack listener
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//
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// Wiring (use I²C0 on the Earle Philhower core):
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// A.GP4 (SDA) ──── B.GP4 (SDA)
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// A.GP5 (SCL) ──── B.GP5 (SCL)
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// A.GND ─── B.GND
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// Wiring to Pico B:
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// A.GP15 (DATA out) ──> B.GP15 (DATA in)
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// A.GP14 (ACK in) <── B.GP14 (ACK out)
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// A.GND ─── B.GND
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//
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// (Real hardware would also need 4.7 kΩ pull-ups on SDA and SCL — the
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// emulator pulls them up automatically.)
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// Every second, A toggles GP15 and waits up to 200 ms for B's ack
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// pulse on GP14. Both events get logged to Serial.
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#include <Wire.h>
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const uint8_t SLAVE_ADDR = 0x42;
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const int DATA_OUT = 15;
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const int ACK_IN = 14;
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void setup() {
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Serial.begin(115200);
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Wire.setSDA(4);
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Wire.setSCL(5);
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Wire.begin(); // master mode
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delay(500);
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Serial.println("Pico A — I2C master ready.");
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pinMode(DATA_OUT, OUTPUT);
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pinMode(ACK_IN, INPUT);
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pinMode(LED_BUILTIN, OUTPUT);
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delay(300);
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Serial.println("Pico A — handshake ready.");
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}
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bool ledState = false;
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uint32_t counter = 0;
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int lastAck = LOW;
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bool dataState = false;
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void loop() {
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ledState = !ledState;
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Wire.beginTransmission(SLAVE_ADDR);
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Wire.write(ledState ? 0x01 : 0x00);
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uint8_t err = Wire.endTransmission();
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// Toggle the data line every second
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dataState = !dataState;
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digitalWrite(DATA_OUT, dataState ? HIGH : LOW);
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digitalWrite(LED_BUILTIN, dataState ? HIGH : LOW);
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counter++;
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Serial.print("[A] sent #");
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Serial.print(counter);
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Serial.print(" DATA=");
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Serial.println(dataState ? "HIGH" : "LOW");
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Serial.print("→ slave ");
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Serial.print(ledState ? "ON " : "OFF");
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Serial.print(" (err=");
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Serial.print(err);
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Serial.println(")");
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// Watch for an ack pulse from B for up to 200 ms
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uint32_t deadline = millis() + 200;
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bool acked = false;
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while (millis() < deadline) {
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int v = digitalRead(ACK_IN);
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if (v != lastAck) {
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lastAck = v;
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acked = true;
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Serial.print("[A] ack edge (ACK=");
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Serial.print(v ? "HIGH" : "LOW");
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Serial.println(")");
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break;
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}
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}
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if (!acked) Serial.println("[A] no ack within 200 ms");
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delay(1000);
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delay(800);
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}
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`,
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},
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@ -2913,55 +2926,59 @@ void loop() {
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boardKind: 'pi-pico-w',
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x: 520,
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y: 120,
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code: `// Pico B — I²C slave at address 0x42
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// Receives 1-byte commands from Pico A and toggles LED_BUILTIN.
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code: `// Pico B — receiver + ack pulser
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//
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// Reads GP15 (DATA in). On every transition, toggles GP14 (ACK out)
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// to tell Pico A it saw the change. Built-in LED mirrors GP15 so
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// you can watch the data line visually.
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#include <Wire.h>
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const uint8_t MY_ADDR = 0x42;
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void onReceive(int howMany) {
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while (Wire.available()) {
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uint8_t cmd = Wire.read();
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digitalWrite(LED_BUILTIN, cmd ? HIGH : LOW);
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Serial.print("[B] cmd=0x");
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Serial.print(cmd, HEX);
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Serial.println(cmd ? " → LED ON" : " → LED OFF");
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}
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}
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const int DATA_IN = 15;
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const int ACK_OUT = 14;
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void setup() {
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Serial.begin(115200);
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pinMode(DATA_IN, INPUT);
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pinMode(ACK_OUT, OUTPUT);
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pinMode(LED_BUILTIN, OUTPUT);
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Wire.setSDA(4);
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Wire.setSCL(5);
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Wire.begin(MY_ADDR); // slave mode at 0x42
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Wire.onReceive(onReceive);
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delay(500);
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Serial.print("Pico B — I2C slave ready at 0x");
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Serial.println(MY_ADDR, HEX);
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digitalWrite(ACK_OUT, LOW);
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delay(300);
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Serial.println("Pico B — handshake responder ready.");
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}
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int lastData = -1;
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bool ack = false;
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void loop() {
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// Nothing to do — Wire.onReceive is event-driven.
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int d = digitalRead(DATA_IN);
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if (d != lastData) {
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lastData = d;
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digitalWrite(LED_BUILTIN, d);
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Serial.print("[B] DATA=");
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Serial.print(d ? "HIGH" : "LOW");
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// Toggle ACK to acknowledge the edge
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ack = !ack;
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digitalWrite(ACK_OUT, ack ? HIGH : LOW);
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Serial.print(" → ACK=");
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Serial.println(ack ? "HIGH" : "LOW");
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}
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}
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`,
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},
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],
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components: [],
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wires: [
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// SDA bus: A.GP4 ↔ B.GP4
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// DATA: A.GP15 → B.GP15
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{
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id: 'w-sda',
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start: { componentId: 'pi-pico-w', pinName: 'GP4' },
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end: { componentId: 'pi-pico-w-2', pinName: 'GP4' },
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color: '#0088ff',
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id: 'w-data',
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start: { componentId: 'pi-pico-w', pinName: 'GP15' },
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end: { componentId: 'pi-pico-w-2', pinName: 'GP15' },
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color: '#22cc22',
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},
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// SCL bus: A.GP5 ↔ B.GP5
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// ACK: B.GP14 → A.GP14
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{
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id: 'w-scl',
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start: { componentId: 'pi-pico-w', pinName: 'GP5' },
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end: { componentId: 'pi-pico-w-2', pinName: 'GP5' },
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id: 'w-ack',
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start: { componentId: 'pi-pico-w-2', pinName: 'GP14' },
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end: { componentId: 'pi-pico-w', pinName: 'GP14' },
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color: '#ffaa00',
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},
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// GND
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@ -2972,7 +2989,7 @@ void loop() {
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color: '#000000',
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},
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],
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tags: ['rp2040', 'pico', 'multi-board', 'i2c', 'wire'],
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tags: ['rp2040', 'pico', 'multi-board', 'gpio', 'handshake', 'bidirectional'],
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},
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{
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