Wireless data acquisition is a field that has seen an amazing growth in the past few years. With the technology advancements we have seen in the world of microcontrollers added to the big push of Internet of Things measurements applications, it is now possible to offer the community low cost options for wireless data acquisition that can also be programmed with LabVIEW.
Low Cost Wireless Data Acquisition
The Programmable Wireless Stamp (PWS) is a low cost micro-controller based wireless board tailored to general test and measurement, wireless data acquisition and IoT applications. The PWS is based off of the ESP-WROOM-02, a high performance wireless SOC by Expressif, especially designed for space and power constrained wireless data acquisition and IoT applications. At the heart of the ESP-WROOM-02 SOC is the ESP8266 chip. An Arduino Compatible target that packs a serious punch with a 32-bit low power micro-controller with CPU clock of 80MHz, 50KB of user available RAM and an external 16MB of Flash memory. The PWS microcontroller is comparable in clock speed to the Arduino Due but its external Flash memory provides a 31X improvement over the 512k of Flash memory in the Arduino Due. The PWS onboard WiFi capability replaces the need for a WiFi Shield; and its I/O expandability of plug and play sensors and PMOD I/O modules provides a small footprint Test and Measurement ready solution at a lower cost.
The Programmable Wireless Stamp include a general purpose I/O connector for direct sensor connectivity as well as three PMOD connectors, one I2C, one SPI, and one UART/GPIO for plug and play I/O extension and utilization of the growing ecosystem of PMOD signal conditioning modules.
The PMOD is a standard created by Digilent that allows for precision data conversion, high-accuracy timekeeping, precision analog generation as well as advanced application specific functionality such as ambient-light sensing, capacity sensing and many others to have a common communication interface within a system. Digilent offers several off the shelf PMOD modules that can be directly connected to the PWS. The PWS augments that functionality by allowing, programmability and decision making in real time as well as wireless connectivity and local data storage to the data produced by these peripheral modules.
The PMOD ecosystem is expanding rapidly. Companies like Maxim, Linear Technologies and Analog Devices, the supplier of the ADCs used by National Instruments on their data acquisition devices, have created several reference designs that are offered to the community via PMOD modules. Maxim, for example, offers a wide variety of analog, mixed-signal and sensor PMOD modules.
The Stamp can be powered by an external Lithium Polymer battery for standalone operation. It will also include battery charger capability and will constantly monitor its battery health status, generating user notifications via Whatsapp messages when it is time for battery charging. Battery charging can be accomplished by simply plugging the PWS on a computer USB port.
The Stamp provides 11 3.3V digital I/O pins and one 10-bit ADC pin, as well as HSPI, UART, SPI, I2C and I2S interfaces. However, the onboard PMOD connectors allow for higher horse power ADC channels to be plugged into the board if the wireless data acquisition application so requires. If a PMOD module is plugged to the Stamp, the Stamp resources that are not assigned to the PMOD module can be normally accessed at the board GPIO connector and used.
A SD Card can be inserted in the Stamp’ SD Card connector for local data logging. The HW includes a Real Time Clock (RTC) for time stamped sensor data logging.
The plug and play connectivity as well as wireless, local storage and real time clock on the hardware and programmability in either C-language or LabVIEW to run embedded in the PWS microcontroller makes he the PWS the perfect platform for simple real time wireless, stand alone control, monitoring and data logging applications. Download the LabVIEW VI Package Manager file from this public repository.
The PWS platform includes a Smart Phone App that allow both Android and iPhone users to quickly configure its wireless network parameters for remote connectivity; as shown below.
A full set of LabVIEW API VIs is made available for easy access to the Stamp peripherals, as well as ready to deploy data logging applications for local and cloud based data storage are provided to jump start your IoT and wireless data acquisition applications. You can download the full palette set free of charge from VI Package Manager under the name Programmable Wireless Stamp (PWS). The Software library also has a model page on the LabVIEW Tools Network.
The Programmable Wireless Stamp can be programmed with National Instruments LabVIEW via the Arduino Compatible Compiler for LabVIEW. Through the utilization of the Arduino Compatible Compiler for LabVIEW, users can deploy LabVIEW code via USB cable to run embedded and standalone in the Stamp. This programming capability allows the user to create fully custom solutions from scratch or to extend and tailor the 60+ shipping examples to fit your specific project requirements. A separate LabVIEW palette including all supported LabVIEW primitives as well as PWS core API VIs is provided for the convenience of the user. The LabVIEW palette also includes two templates that can be used to jump start your wireless data acquisition, monitoring and control application.
Furthermore, the LabVIEW installer package also includes an Extended Functionality set, which comes with a set of API VIs that were created to facilitate the expandability of the PWS board functionality with the plug and play addition of the following modules and sensors:
- DHTxx Temperature and Humidity Sensors and off the shelf DHTxx based modules
- 1-wire Digital Thermometer sensors
- MAX21855 Cold-junction compensated thermocouple digital converter
- 180-degree Servo Motors
- Custom or off the shelf modules powered by the MCP3208 – An 12-bit four pseudo-differential or eight single ended 100 Ksps ADC chip
- Custom or off the shelf modules powered by the LTC2499 – An 24-bit delta sigma eight differential or sixteen single ended ADC chip
- External Serial EEPROM
- RFID Modules
- Camera modules for simple image applications
- PMOD GPS
- PMOD Thermocouple
- JSON API VIs for simple data exchange between networked PWSs among themselves and/or other networked nodes
The Programmable Wireless Stamp is ideally suited for the following applications:
- Low-power remote data logging
- Low-power remote monitoring and control
- Real-time data acquisition and control
- Distributed embedded monitoring and control
- Wireless data acquisition
- Simple real-time image applications
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