I’ll create only the new comparison guide and leave all existing files unchanged. The brief’s “Related in Flux” URLs point to unrelated LED parts, so I’ll use the BME280 guide and AHT20 links supplied earlier in the brief instead.
For aht20 vs bme280, the main difference is pressure sensing: BME280 measures pressure, humidity, and temperature; AHT20 measures humidity and temperature. Pick BME280 when pressure or SPI is required, and AHT20 for a humidity-and-temperature-only I²C design.
Scope: exact bare Bosch BME280 and bare Aosong/ASAIR AHT20, not breakout modules, AHT10, AHT21, or other sensor variants. Electrical operating limits are not absolute-maximum stress ratings. Implementation choices below are labeled as engineering guidance.
Checked the saved guide’s structure, citations, and both datasheet pinouts.
Values left out: matched-condition current/power comparisons, conversion-speed rankings, and full-range maximum accuracy limits. I did not establish sufficiently verified, comparable values for those claims. Prices and stock were excluded as requested.
Pinout risk: the parts are not pin- or footprint-compatible. Replacement requires PCB remapping and new firmware, and AHT20 does not retain pressure sensing. No hardware testing was performed.
BME280 vs DHT22 comes down to pressure sensing and interfaces: BME280 adds pressure and I²C/SPI; DHT22 measures humidity and temperature. Choose BME280 for an integrated digital-bus design with pressure, or DHT22 for a leaded humidity/temperature sensor with infrequent reads.
Scope: bare Bosch Sensortec BME280 in its metal-lid LGA package versus Aosong DHT22 in the standard four-lead vented package. The selected Aosong datasheet also calls DHT22 “AM2302”; this comparison does not extend its pinout to wired AM2302 assemblies or third-party breakout boards.
Quick answer
Table
Choose BME280 if...
Choose DHT22 if...
You need pressure as well as humidity and temperature.
You need humidity and temperature only.
Your host already uses I²C or SPI.
Your host can implement the sensor's dedicated single-data-line protocol.
You need a compact surface-mount sensor.
A larger leaded sensor suits your assembly and enclosure.
You want configurable measurement triggering.
Reads spaced more than 2 s apart meet your needs.
The choices above follow Bosch's interface/package and forced-mode descriptions and Aosong's package/protocol/read-interval descriptions.
Electrical comparison
Operating supply ranges below are operating limits, not absolute-maximum stress ratings. They are not a claim of matched accuracy at every supply or temperature.
Table
Parameter
BME280
DHT22
What it means for your design
Measured quantities
Humidity, pressure, temperature.
Humidity and temperature.
Replacing BME280 removes pressure measurement.
Operating sensor supply
VDD = 1.71–3.6 V; maximum supply ripple 50 mV peak-to-peak, per operating-conditions table.
VDD = 3.3–6 V DC, per DHT22 technical table; no additional supply-test condition is given there.
A nominal rail must remain inside the chosen sensor's range after tolerance and wiring drop.
Interface supply arrangement
Separate VDDIO = 1.2–3.6 V, per operating-conditions table.
VDD, DATA, NC and GND; no separate interface-supply pin.
Do not transfer BME280's independently powered logic arrangement to DHT22 unchanged.
Host interface
I²C or three-/four-wire SPI.
Dedicated single-bus digital protocol.
Neither wiring nor driver is interchangeable; DHT22's protocol is not I²C.
Measurement scheduling
Forced mode performs a measurement, returns to sleep, and requires another trigger for the next measurement.
Collecting/read interval must be greater than 2 s.
Redesign the polling schedule rather than retaining the existing bus loop.
Host processing
Raw ADC data requires compensation using stored factory calibration parameters.
Sends humidity/temperature data and a checksum; the device supplies calibrated digital output.
Replace the data decoder and validation, not just the sensor name in firmware.
The table is a compact replacement cross-check, not a duplicate of the full application-guide pin descriptions. Pin order was checked against Bosch's Figure 16 and pin table and Aosong's package/pin drawing and connection table.
Clockwise numbering in top view, pads hidden; counterclockwise in bottom view, pads visible. Use the pin-one marker.
DHT22, four-lead vented package
1 VDD; 2 DATA; 3 NC; 4 GND.
Facing the vented front, mounting tab above and leads below: left to right.
The pin order is different. BME280 and DHT22 are neither pin-compatible nor footprint-compatible; neither replaces the other on the same footprint without changes. In particular, numbered terminal 1 is GND on BME280 but VDD on DHT22.
Design differences in a circuit
Supply and drive levels: Recheck the sensor supply over tolerance, ripple and cable drop. BME280 has separate sensor/interface supplies; DHT22 does not. Engineering guidance: choose a host-compatible DATA pull-up rail and verify both directions of logic signaling; do not assume a higher sensor supply makes the host GPIO tolerant of that voltage.
Passives and signal wiring: Bosch's I²C circuit uses a 100 nF capacitor on each supply and normally 4.7 kΩ pull-ups on SDA and SCL, selected for bus loading and timing. Aosong permits a 100 nF VDD-to-GND filtering capacitor. When changing to DHT22, replace this sensor's bus branch with DATA wiring and its required biasing; do not remove shared I²C pull-ups needed by other devices. Engineering guidance: select DATA biasing against the actual host and wiring and validate the waveform.
Firmware: Remove the BME280 register/configuration and compensation path. Implement DHT22 timing, decode its returned humidity/temperature fields, validate its checksum, send no instructions during the first 1 s after power-up, and space reads more than 2 s apart.
Worked example: migrating a nominal 3.3 V sensor branch
Assume, as an engineering example rather than a measured board condition, that the existing regulator is 3.3 V nominal with ±3% total DC tolerance at the sensor and no additional wiring drop. The resulting range is 3.201–3.399 V, calculated as 3.3 V × (1 ± 0.03). This lies within BME280's VDD and VDDIO operating ranges, but its lower end is below the selected DHT22 datasheet's 3.3 V DC minimum; the rail cannot simply be carried over as a guaranteed DHT22 supply. Ripple must also meet the BME280 requirement independently.
For the DHT22 redesign, revise the supply so its worst-case voltage at the sensor stays within the cited operating range, then resolve host logic compatibility before connecting DATA. Fit the optional 100 nF supply-filter capacitor and, as an example firmware choice, poll every 3 s after the startup inhibit; 3 s is greater than Aosong's required 2 s read interval. This example does not establish an accuracy or power-consumption equivalence.
PCB and layout differences
Footprint: Replace the surface-mount LGA land pattern with a leaded-sensor footprint or a suitably wired connector; pin count, pad geometry and power mapping differ.
Routing: BME280's clock/data or SPI routes become DHT22's bidirectional DATA connection. Engineering guidance: reassess pull-up loading, noise pickup and signal edges, especially if the sensor moves onto a cable.
Thermal placement: Bosch notes that its internal sensor temperature depends on PCB temperature, self-heating and ambient conditions. Engineering guidance: a leaded DHT22 permits different placement, but changing package alone does not guarantee ambient-temperature accuracy; evaluate airflow and nearby heat in the final enclosure.
Can I replace BME280 with DHT22?
Yes, with schematic, PCB and firmware changes, and only if pressure measurement is no longer required. No, it is not a drop-in replacement. BME280 provides pressure and standard digital-bus interfaces, whereas DHT22 provides humidity/temperature over its dedicated protocol.
Required changes:
Replace the footprint and remap power, ground and DATA using the checked pin order above.
Revalidate supply tolerance and host logic levels; revise decoupling and DATA biasing.
Replace the driver, startup handling, read schedule and checksum/data processing.
Remove pressure-dependent features or retain a separate pressure sensor through a new design review.
FAQ
Which should I use: BME280 vs DHT22?
Use BME280 when pressure or an I²C/SPI interface is required. Use DHT22 when humidity/temperature alone, a leaded package and reads more than 2 s apart fit the application.
Does DHT22 measure air pressure?
No; its documented measurements are relative humidity and temperature. Replacing BME280 with DHT22 therefore removes the pressure channel.
Can DHT22 use the BME280 I²C driver?
No. DHT22 uses its own single-bus transaction and checksum format, so it needs different firmware and wiring rather than an I²C address change.
Can both sensors run from the same supply?
Their cited sensor-supply operating ranges overlap from 3.3 to 3.6 V DC, derived from the two manufacturers' limits. That overlap alone does not verify GPIO compatibility, supply tolerance, ripple or measurement accuracy; check those separately.
DHT22 part page — library reference; verify the selected physical package against its drawing before use.
Sources
Bosch Sensortec BME280 datasheet, cover revision 1.24, release February 2024, document BST-BME280-DS001-24. Some internal extracted footers retain earlier revision text; the identification here follows the cover. Primary evidence: operating conditions, interfaces, output compensation, Figure 16/pin table and I²C connection diagram.
Aosong Electronics DHT22 datasheet, manufacturer-authored PDF hosted by SparkFun. Revision: not stated. Date: not stated. The PDF identifies Aosong Electronics Co., Ltd.; no revision/date is invented. Primary evidence: technical table, package/pin drawing, connection diagram and communication instructions.
Quick answer
Electrical comparison
Pinout and package differences
Design differences in a circuit
Worked example: migrating a nominal 3.3 V sensor branch