Many of Sensirion's evaluation kits are shipped with cables that connect our sensor to our SensorBridge interface hardware. To evaluate the performance of the sensors, it's generally best to use SensorBridge together with the ControlCenter software.
If the aim is to integrate our sensors into a prototype or a custom design without designing a custom PCB, there are options such as breakout boards from Sensirion's ecosystem partners that provide a plug-and-play type experience. However, if you already have an evaluation kit or if the breakout board is not available, it is also possible to build a prototype with our evaluation kit sensors. When it comes to sensors on flex PCB, this can be a little tricky. This article discusses three ways to connect the sensors on flex PCBs from the evaluation kit to prototyping boards or custom designs.
Sensirion evaluation kits
Sensirion's evaluation kits are designed to facilitate the testing of our sensor technologies across various applications. These kits provide developers and engineers with the necessary tools to efficiently assess sensor performance.
The evaluation kits usually contain the following:
- Sensors pre-mounted on dedicated boards or flex-PCBs when the sensor is a chip.
- Cables either with direct USB support or compatible with the Sensorbridge.
The Sensorbridge is a hardware bridge bought separately that connects two sensors to a desktop computer. The sensor connects to the SensorBridge using RJ45 ports.
SEK-SensorBridge-Connecting bridge with two sensor ports
There are different ways to take advantage of the evaluation kits:
- Plug-and-play testing: By pairing the Sensorbridge with the sensors or using a cable with direct USB support, one can use the ControlCenter software provided by Sensirion to visualize live data, change parameters and log data. More information can be found in the ControlCenter software manual link
- Advanced software testing: It is also possible to use Python libraries to communicate with the evaluation kits. It enables more control and allows testing the sensor with the software logic of the targeted application. The python libraries can be found in the Sensirion Github repository link
- Hardware prototyping: It is possible to integrate the evaluation kit sensors into a custom design. For sensors with standard connectors such as liquid flow or pressure sensors, it is recommended to use connectors to headers cables. This article focuses on how to achieve it for sensors on flex PCBs.
Required Material
- 1x compatible Sensirion sensor with evaluation kit cable for SensorBridge
- 1x Development board (such as an Arduino or Raspberry Pi)
- 4x male to female jumper cable
- 1x RJ45 breakout board of our choice
Pin Layout
Setup
As an example, the following RJ45 breakout board can be used: Amazon.com: RJ45 Ethernet Connector Breakout Board w/LED 0.1" (2.54mm) Male Header : Electronics
- Step 1: Identify the male header on the RJ45 breakout board corresponding to each I2C functions.
- Step 2: Identify the pins corresponding to each I2C functions on your development board.
- Step 3: Use the jumper cables to connect the RJ45 breakout board to your development board
- Step 4: Plug the RJ45 cable end of the evaluation kit into the RJ45 breakout board
Example setup using an Arduino Uno board with pull-up resistors added to the SCL and SDA lines:
Required material
- 1x compatible Sensirion sensor with evaluation kit cable for SensorBridge
- Stripping and cutting tool
- 2x male to male jumper cables (e.g. Male/Male Jumper Wires)
- Soldering station and heat shrinks
- 1x development board of your choice
Pin Layout
Please check the RS485 connector end and identify the color for each pin to identify the VDD, GND SDA and SCL pins.
While the standard color association can be found below, it is highly recommended to check using the pinouts as change in cable manufacturing color could occur.
Setup
- Step 1: Cut the evaluation kit cable to your desired length. Cutting the RS485 cable going into the Sensorbridge's ports will expose 4 wires. Also, cut the male-to-male jumper cables in half. You will get 4 jumper cables each terminated with a male header on one end and a flying wire on the other end.
- Step 2: Strip the black insolation and strip each newly exposed wire of colors. Strip the male-to-male jumper cables on the wires end.
- Step 3: Insert heatsinks into each jumper cable.
- Step 4: Solder each exposed wire from the evaluation kit cable to a jumper cable. Shrink the heatsinks on the soldered connection to protect it.
- Step 5: Identify the wire color of each I2C function and plug it into the breadboard to connect it to your prototyping board. Don't forget the pull-up resistors necessary for the I2C bus.
Required material
- 1x Adafruit Touch Screen Breakout Board for 4 pin 1.0mm FPC (https://www.adafruit.com/product/3575)
- Sensirion sensor on Flex-PCB from an evaluation kit
- 4x jumper wires, female to male (e.g. Female/Male Jumper Wires)
- Development board of your choice
- Soldering station
The key ingredient here is the "Touch Screen Breakout Board", which is originally made to interface with a touch screen, but which shares the connector format with Sensirion’s sensors on Flex-PCB.
Pin Layout
Setup
- Step 1: Solder the header pins into the breakout board
- Step 2: Connect the header pins of the breakout board into the corresponding pins of the development board using the jumper wires
- Step 3: Insert delicately the flex PCB into the breakout board slot, the top of the sensor on the same side as the top of the breakout board with the labels.
Example circuit using an Arduino Uno board with pull-up resistors added to the SCL and SDA lines:
This article showed 3 options to interface sensors on flex-PCBs from Sensirion evaluation kits with prototyping boards. Once the setup is established, drivers can be found below to speed up the integration.
Sensirion/info: Overview over the Sensirion Github repositories & available sensor drivers
To conclude, please find some pros and cons of each proposed solution below:
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