In our daily applications, barometric sensors often use two main digital interfaces: I²C (also called IIC) and SPI. Knowing their differences, performance, and use cases helps engineers and hobbyists pick the right one and optimize system designs. Walk you through:
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1. Defining I²C vs. SPI Pressure Sensors
I²C (Inter‑Integrated Circuit) and SPI (Serial Peripheral Interface) are common digital bus protocols used between microcontrollers and MEMS barometric sensors.
1.1 Basics of I²C
Two wires: Clock (SCL) and Data (SDA).
Multi-master/multi-slave on one bus, addresses identify devices.
Half‑duplex: Send or receive at one time.
1.2 Basics of SPI
Four wires: SCLK, MOSI, MISO, and CS.
Single-master/multiple-slave, use CS to select slaves.
Full‑duplex: Simultaneous read/write.
1.3 Barometer Use Cases
I²C sensors: Fewer lines, lower cost, better for tight pin budgets and many devices.
SPI sensors: Higher speed, stronger noise immunity, ideal for time‑critical data.
비고: SOP 및 DIP 패키지 제품의 연결 정의는 동일합니다.
2. Is IIC the Same as I²C?
IIC is simply an old spelling of I²C—same protocol, same features.
2.1 Naming History
I²C: Coined by Philips (now NXP) as “Inter-Integrated Circuit.”
IIC: Simplified shorthand in older datasheets.
2.2 Identical Specifications
Whether IIC or I²C, voltage levels, timing, and addressing match exactly—drivers are interchangeable.
2.3 Practical Tip
When you see IIC in docs, treat it as I²C—no extra learning needed.
3. Speed Comparison: I²C vs. SPI
Speed often drives your interface choice.
3.1 I²C Speeds
Standard: up to 100 kHz
Fast: up to 400 kHz
Fast‑Plus: up to 1 MHz (device‑dependent)
3.2 SPI Speeds
Commonly several MHz up to tens of MHz; some designs reach 100 MHz
Depends on line length, capacitance, and MCU capability
3.3 Throughput in Practice
SPI’s full‑duplex mode lets you send and receive at once. I²C’s half‑duplex plus address overhead slows it down. At 1 MHz, I²C sends 2 bytes in ~20 μs; at 10 MHz, SPI does it in ~1.6 μs.
4. Using SPI and I²C Together
Sometimes you need both buses in one system.
4.1 Hardware Sharing
Use separate pins or a multiplexer (MUX) to host both SPI and I²C on one MCU.
Watch level‑shifting and MUX timing requirements.
4.2 Driver Support
Platforms like STM32 or Arduino natively run both SPI and I²C drivers simultaneously.
Manage interrupts and DMA channels to avoid conflicts.
4.3 Real‑World Example
In our sensor application solution for a UAV barometer design, I²C is used for low-speed environmental monitoring and SPI for high-frequency data acquisition, both working in tandem for high resource utilization and no interference.
5. Signal Types & Levels: Analog or Digital? Active High or Low?
Both I²C and SPI are digital, but you still need to know signal behavior.
5.1 SPI Digital Signals
MOSI/MISO/SCLK are digital pulses.
CS is digital (usually active‑low).
5.2 I²C Digital Signals
SDA/SCL are open‑drain outputs, need pull‑ups.
Idle bus: both lines high; pull low for start, clock, or data‑0.
5.3 Logic Levels
For WF100DP digital sensor series modules：
SPI CS: typically “low‑active.”
I²C: “high” = idle/stop, “low” = start or data‑0 (or I2C, leave it alone).
6. Choice Guide: SPI or I²C?
When picking a barometric sensor interface, balance power, speed, pin count, and system layout.
6.1 When to Pick Which
핀 - 핀 & 많은 장치 → I²C
높은 대역폭 & 실시간 요구 → SPI
6.2 Hands‑On Advice
Start prototypes with I²C for quick tests. If you hit performance walls or stricter timing, switch to SPI. Always bench‑test error rates, power draw, and coding effort before locking in your choice.
결론
Through this article, we have made a comprehensive analysis of the definition, performance, parallel use, signal characteristics and selection points of I²C (IIC) and SPI in air pressure sensor applications. In short: I²C is simple, flexible and suitable for multiple expansion; SPI is high-speed, stable and suitable for real-time acquisition. We hope you will find the most suitable interface solution in your next barometer design, so that the device can save cost and have high precision resolution and sampling rate.
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