Qwiic Pressure Sensor (BMP384) Hookup Guide
El Duderino 
Hardware Overview
Let's take a closer look at the BMP384 sensor and other hardware present on these Qwiic breakouts.
BMP384 Pressure Sensor
The BMP384 is a high-resolution digital pressure sensor from Bosch with a wide measurement range (300hPa to 1250hPa) and excellent accuracy.
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The sensor measures pressure and temperature with an average accuracy of 0.09hPa (300hPa to 1250hPa) and 0.35°C (at 25°C), respectfully. The sensor supports up to 21-bit resoluation as well as oversampling, low-pass filtering and a max sampling rate of 200Hz making it suitable for a wide range of applications. It uses a gel-filled cavity to improve the sensor's resistance to moisture (though not waterproof) so it works well in applications where the sensor may be exposed to liquids (outdoor sensor, drone, weather balloon etc.). For a complete overview of the sensor, refer to the datasheet.
The BMP384 accepts a supply voltage between 1.65V to 3.6V. The breakout runs the sensor at 3.3V supply and logic when connected to a Qwiic system. The BMP384 supports data transfer speeds up to 3.4MHz over I2C and speeds up to 10MHz over SPI. The sensor also includes a configurable Interrupt pin broken out to a pin on the PTH header.
The BMP384 has three operating modes: Sleep Mode (Default after reset), Normal Mode and Forced Mode. While in Sleep Mode the sensor is idle and consumes ~2µA. While in Normal Mode, the sensor automatically cycles between measurement and standby periods and consumes ~700µA at peak current draw during measurements. Forced Mode allows direct control of measurements to wake the sensor from Sleep Mode, take a single-shot measurement and return the device to Sleep Mode.
| Parameter | Min. | Typ. | Max. | Units | Notes |
|---|---|---|---|---|---|
| Operating Temperature | -40 | 25 | 85 | °C | |
| Operating Pressure | 300 | - | 1250 | hPa | |
| Relative Accuracy | - | ±9 | - | Pa | At 900-1110hPA & 25-40°C |
| Absolute Accuracy | - | ±50 | - | Pa | At 300-1100hPa & 0-65°C |
| Temp. Coeff. Offset | - | ±1.0 | - | Pa/K | At 900hPa & 25-40°C |
| RMS Noise in Pressure 1 | - | 1.2 | - | Pa | Full bandwidth, highest resolution. |
| - | 0.03 | - | Pa | Lowest bandwidth, highest resolution. | |
| Sampling Rate 2 | - | - | 200 | Hz | Depends on oversampling settings osr_t and osr_p. |
2. Refer to section 3.9 of the BMP384 datasheet for more information.
Communication Interfaces - I2C & SPI
The Qwiic Pressure Sensor (BMP384) breakouts communicate over I2C by default. The Standard size breakout also supports using the BMP384 over SPI (No SPI on the Qwiic Micro version unfortunately).
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The Standard breakout routes the I2C interface to a pair of Qwiic connectors as well as a 0.1"-spaced PTH header for users who prefer a traditional, soldered connection. This PTH header shares the SPI connections and also includes the Interrupt pin.
The Micro breakout routes the I2C interface to a single Qwiic connector and includes PTHs for the Interrupt pin as well as a second Ground pin for projects that require that connection.
The boards set the BMP384's I2C address to 0x77 by default. Adjust the ADR jumper to change to the alternate address (0x76) or leave it completely open to use the SPI interface. More information on this jumper in the Solder Jumpers section below.
Solder Jumpers
The breakouts have three solder jumpers labeled: I2C, ADR and LED.
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The I2C jumper connects a pair of 2.2kΩ resistors to the SDA/SCL lines. Leave these enabled unless you have a large amount of I2C devices on the same bus.
The ADR jumper sets the I2C address of the BMP384 to 0x77 by default (0x76 alternate). It also controls whether it operates via I2C or SPI. Open the jumper completely to set the BMP384 to communicate via SPI (Standard Size only).
The LED jumper completes the Power LED circuit. Open the jumper to disable the Power LED if desired.
Board Dimensions
The standard size Qwiic breakout matches the 1.0" x 1.0" (25.4mm x 25.4mm) form factor for Qwiic breakouts with two mounting holes that fit a size 4-40 screw. The Micro version of this breakout matches the Qwiic Micro form factor and measures 0.75" x 0.30" (24.65mm x 7.62mm) and has one mounting hole that fits a size 4-40 screw.
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