Wire Library Compatibility
Talk to I2C devices on A4 (SDA) and A5 (SCL).
- Pinned version
- 1.0
- Last matching compile evidence
- 2026-10-25
- Toolchain
- avr-gcc-wasm@0.2.0
- Primary headers
- Wire.h
Dependencies and practical limits
Talk to I2C devices on A4 (SDA) and A5 (SCL).
The description/example uses Uno A4/A5; Mega uses D20/D21 and Leonardo/Micro use D2/D3. Consult the selected board pin table.
An I2C address or missing pull-up is a wiring/runtime issue, not proof of a failed library compile.
No additional catalog dependencies are required.
For a missing header, first compare the include to the example below. For an undeclared identifier, inspect the first diagnostic and selected board rather than changing every library version.
Board compile matrix
These are recorded compile/link results for the current build and exact source hash. UNTESTED means no matching proof, not an assumed pass. Memory values belong to the listed example and exclude runtime stack/heap or dynamic buffers.
| Board/profile | Result | Flash bytes | Static SRAM bytes | Last tested |
|---|---|---|---|---|
| Arduino Uno R3 — ATmega328P | PASS | 4494 | 408 | 2026-10-25 |
| Arduino Nano V3 — ATmega328P (new bootloader) | PASS | 4494 | 408 | 2026-10-25 |
| Arduino Nano V3 — ATmega328P (old bootloader) | PASS | 4494 | 408 | 2026-10-25 |
| ATmega328PB — 16 MHz | PASS | 4706 | 408 | 2026-10-25 |
| Arduino Mega 2560 — ATmega2560 | PASS | 5258 | 408 | 2026-10-25 |
| Arduino Leonardo — ATmega32U4 · native USB | PASS | 6846 | 372 | 2026-10-25 |
| Arduino Micro — ATmega32U4 · native USB | PASS | 6848 | 372 | 2026-10-25 |
| Arduino Pro Mini — 5 V · 16 MHz | PASS | 4494 | 408 | 2026-10-25 |
| Arduino Pro Mini — 3.3 V · 8 MHz | PASS | 4482 | 408 | 2026-10-25 |
Build: e0f6d304cce4ae0a0989a9b1300cbc1a21a595e5e3e7f57ed0ab3468ecf7940b. Library source hash: f9c051e82b7ab5598bf347dfaaec2497ec171fbed8c3ad8de92ed035b3152d69. Compilation does not certify physical peripherals, timing or USB upload.
I2C scanner example
This is the actual pinned example available in Circuitera. Pin choices and wiring in a general example use Uno unless otherwise stated; review the selected board reference for other targets.
#include <Wire.h>
void setup() { Wire.begin(); Serial.begin(9600); }
void loop() {
Serial.println(F("Scanning I2C: SDA=A4, SCL=A5"));
for (byte address = 1; address < 127; address++) {
Wire.beginTransmission(address);
if (Wire.endTransmission() == 0) {
Serial.print(F("Found 0x")); Serial.println(address, HEX);
}
}
delay(3000);
}
Projects using Wire
Upstream source and documentation ↗
Read the test methodology →