Grzegorzbecker: Created page with "jzpdf ==== Description==== KAmod Si7021 - Si7021 Temperature and Humidity Sensor Module
Module with an affordable and easy-to-use Si7021 temperature and humidity sensor from Sillicon Labs. The sensor communicates via I2C and can measure temperature in the range of -40 to 125°C and relative humidity in the range of 0 to 100% RH. The board is equipped with I2C Qwire connectors (compatible with Qwiic/STEMMA QT) and a single-row connector with a 2.54 mm pitch..."

2025-10-17T11:32:08Z

Created page with "__jzpdf__ ==== Description==== KAmod Si7021 - Si7021 Temperature and Humidity Sensor Module Module with an affordable and easy-to-use Si7021 temperature and humidity sensor from Sillicon Labs. The sensor communicates via I2C and can measure temperature in the range of -40 to 125°C and relative humidity in the range of 0 to 100% RH. The board is equipped with I2C Qwire connectors (compatible with Qwiic/STEMMA QT) and a single-row connector with a 2.54 mm pitch..."

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__jzpdf__
==== Description====
KAmod Si7021 - Si7021 Temperature and Humidity Sensor Module 
Module with an affordable and easy-to-use Si7021 temperature and humidity sensor from Sillicon Labs. The sensor communicates via I2C and can measure temperature in the range of -40 to 125°C and relative humidity in the range of 0 to 100% RH. The board is equipped with I2C Qwire connectors (compatible with Qwiic/STEMMA QT) and a single-row connector with a 2.54 mm pitch. The board includes an LED indicating the presence of power and 4.7 kΩ pull-up resistors for the I2C interface lines, which can be easily disconnected if necessary. <center>
[[File:KAmod_Si7021_1.jpg|none|900px|thumb|center]]
</center>
 
==== Basic Parameters ====
* Based on the Si7021 chip from Sillicon Labs
* Humidity measurement range: 0-80% RH
* Humidity measurement accuracy: ±3% (in the range of 0-80% RH)
* Humidity measurement resolution: ±0.025% RH
* Temperature measurement range: -40...125°C
* Temperature measurement accuracy: ±0.4°C (in the range of -10...+85°C)
* Temperature measurement resolution: ±0.01°C
* Communication via I2C interface (chip address: 0x40)
* I2C '''Qwire'' connectors, JST SH 4-pin 1 mm (compatible with Qwiic / STEMMA QT)
* Power supply voltage: 3.3 V
* Dimensions: 25 x 15 x 4.7 mm
 

==== Standard Equipment ====
 
<center>
{| class="wikitable" style="width: 1100px;"
|-
! style="text-align: center;"|Code
! style="text-align: center;"|Description
|-
| style="text-align: center;"|KAmod Si7021 
| style="text-align: left;"|
* Assembled and powered-up module
* 1 x straight 4-pin goldpin header, 2.54 mm pitch
|}

[[File:KAmod_Si7021_3.jpg|none|600px|thumb|center]]
</center>
 

==== Schematic ====
<center>
[[File:KAmod_Si7021_sch.png|none|1000px|thumb|center]]
</center>
 

==== Signal Layout on the Board ====
The KAmod Si7021 module features two 4-pin I2C Qwire connectors (JST SH 1 mm) compliant with the Qwiic / STEMMA QT standard, allowing for quick connection and expansion of I2C modules without the need for soldering. Additionally, the power and I2C lines are connected to a single-row J1 connector with a 2.54 mm pitch. The signal layout is described on the PCB.

<center>
[[File:KAmod_Si7021_QWIRE.png|none|850px|thumb|center]]
</center>
 

==== Power Supply ====
The KAmod Si7021 module should be powered by a DC voltage of 3.3 V (1.9...3.6 V). 
The board is powered via the '''Qwire''' connector (compatible with Qwiic / STEMMA QT) or a pin header on the '''+3V3''' and '''GND''' pins. The presence of power is indicated by the LED marked '''PWR''' illuminated.
<center>
[[File:KAmod_Si7021_PWR.png|none|600px|thumb|center]]
</center>
 
==== Configuration Jumpers ====
The KAmod Si7021 module is equipped with an SMD jumper to disconnect the "PWR LED" (JP1) and "I2C PULLUPS" jumpers (JP2, JP3) to independently disconnect the pull-up resistors (to the positive power supply terminal) from the I2C bus lines. 
The jumpers are located on the bottom of the board and are factory-shorted (copper trace between the pads). To disconnect the jumpers, cut the board surface with a sharp tool – as indicated by the red lines in the drawing below. Reconnecting the jumpers is possible by applying a drop of solder, which will connect both cut pads of the jumper. <center>
[[File:KAmod_Si7021_JUMPER.png|none|600px|thumb|center]]
</center>
 

==== Dimensions ====
The KAmod Si7021 board dimensions are 25x15 mm. There are two mounting holes on the board, each with a diameter of 3.2 mm.

<center>
[[File:KAmod_Si7021_wym.png|none|800px|thumb|center]]
</center>
 
==== Test Program ====
The test program was written in the Arduino environment for the [https://kamami.pl/esp32/1191671-kamod-esp32-powrs485-plytka-ewaluacyjna-z-modulem-wi-fi-typu-esp32-wroom-i-interfejsem-rs485-5906623488070.html KAmodESP32 POW RS485] board. 
<syntaxhighlight lang="arduino" line>
//ino board: ESP32-WROOM-DA Module
//Hardware Connections:
// KAmod Si7021 ------------- KAmodESP32 POW RS485
// GND ---------------------------- GND
// 3V3 ---------------------------- 3.3V
// SDA ---------------------------- SDA/IO-33
// SCL ---------------------------- SCL/IO-32

#include <Wire.h>
#include <SPI.h>
#include "Adafruit_Si7021.h"

bool enableHeater = false;
uint8_t loopCnt = 0;

Adafruit_Si7021 sensor = Adafruit_Si7021();

void setup() {
Serial.begin(115200);

// wait for serial port to open
while (!Serial) {
delay(10);
}

Serial.println("Si7021 test!");

if (!sensor.begin()) {
Serial.println("Did not find Si7021 sensor!");
while (true)
;
}

Serial.print("Found model ");
switch(sensor.getModel()) {
case SI_Engineering_Samples:
Serial.print("SI engineering samples"); break;
case SI_7013:
Serial.print("Si7013"); break;
case SI_7020:
Serial.print("Si7020"); break;
case SI_7021:
Serial.print("Si7021"); break;
case SI_UNKNOWN:
default:
Serial.print("Unknown");
}
Serial.print(" Rev(");
Serial.print(sensor.getRevision());
Serial.print(")");
Serial.print(" Serial #"); Serial.print(sensor.sernum_a, HEX); Serial.println(sensor.sernum_b, HEX);
}

void loop() {
Serial.print("Humidity: ");
Serial.print(sensor.readHumidity(), 2);
Serial.print("\tTemperature: ");
Serial.println(sensor.readTemperature(), 2);
delay(1000);

// Toggle heater enabled state every 30 seconds
// An ~1.8 degC temperature increase can be noted when heater is enabled
if (++loopCnt == 30) {
enableHeater = !enableHeater;
sensor.heater(enableHeater);
Serial.print("Heater Enabled State: ");
if (sensor.isHeaterEnabled())
Serial.println("ENABLED");
else
Serial.println("DISABLED");

loopCnt = 0;
}
}

</syntaxhighlight>
 

==== Links ====
*[https://wiki.kamamilabs.com/images/9/91/Si7021-A20.pdf Datasheet Si7021-A20]
*[https://wiki.kamamilabs.com/images/9/9a/KAmod_Si7021_3d.zip CAD model (STEP)]

KAmod Si7021 - Revision history