MAXREFDES131# is a sensing solution featuring the Panasonic AMG8833 Grid-EYE® and the Maxim 1-Wire® bus, enabled by the DS28E17. The system enables presence sensing, people counting, and gestures while tethered up to 100m along the 1-Wire bus. The board features RJ-11 connectors and convenient mounting holes for quick evaluation and implementation.
Example source code for interfacing with MAXREFDES131# is available for both Arm® mbed™ and Arduino® platforms. This design conveniently works with MAXREFDES132#, a hardware 1-Wire shield. A demonstration GUI allows for visual feedback of up to 10 daisy-chained MAXREFDES131# 1-Wire Grid-EYE sensors.
As with all Maxim reference designs, the BOM, schematics, layout files, and fab files are all available from the Design Resources tab. In addition, boards are available for purchase.
The future of smart connected devices is bright; however, many of the distinct applications are unclear and waiting to be invented. Clearly, critical components of IoT applications will ensure the safety of people and buildings, movement of commerce, and activation of features. For these reason, MAXREFDES131# is the future of IoT. This unique system marries a high-performance passive IR-sensing array, Panasonic’s Grid-EYE, with Maxim’s 1-Wire bus, for enhanced range and simple interface.
MAXREFDES131# integrates the DS28E17 1-Wire-to-I2C master bridge with the AMG8833 Grid-EYE sensor from Panasonic electronic components. This architecture allows the sensor to be placed up to 100m from the host processor, on the 1-Wire bus. The DS2413 1-Wire dual-channel addressable switch along with the MAX4717 dual-SPDT analog switch allow enumeration of units on the 1-Wire bus. In addition, all units can be put to sleep, or individually selected once enumerated, reducing power consumption.
Example source code for interfacing with MAXREFDES131# has been developed for both mbed and Arduino platforms. A demonstration GUI has also been developed allowing for visual feedback of up to 10 daisy-chained MAXREFDES131# 1-Wire Grid-EYE sensors.
Figure 1 provides a block diagram of MAXREFDES131#.
The design features two RJ-11 jacks, H1 and H2, for interfacing to the hardware and daisy chaining units together. At power up, the MAX4717 comes up with COM1 disconnected from the 1-Wire bus and COM2 connected allowing the host to see the first DS28E17 on the bus.
The DS2413 allows the host to connect/disconnect downstream units of daisy-chained MAXREFDES131# units. In addition, the DS2413 channel controlling the connection of COM2 to the 1-Wire bus also puts the DS28E17 to sleep when COM2 is disconnected from the 1-Wire bus. When the DS28E17 is put to sleep, it disconnects power from the AMG8833 reducing the current consumption of a single MAXREFDES131 from ~8mA to ~0.5mA. The I2C bus of the DS28E17 1-Wire-to-I2C master is also connected to H2 of each MAXREFDES131#.
Figure 1. Block diagram of MAXREFDES131#.
A demonstration GUI and corresponding firmware showcase the interface to and operation of multiple MAXREFDES131# units, daisy chained together. The GUI works on both mbed.org and Arduino platforms. Figure 2 provides a flow chart for the operation of the GUI.
The GUI starts by initializing all controls and enumerating available COM ports. The system disables all controls, except for the “COM Port List” dropdown. Once the user selects a COM port and the firmware responds, the “Enumerate Sensors” push button is enabled.
After the user presses the “Enumerate Sensors” button, the firmware responds with a message containing the number of MAXREFDES131# units attached to the 1-Wire bus. In addition, the “Select Sensor” dropdown will be enabled.
After the user selects a sensor from the dropdown list, the “Receive Data” push button will be enabled. Once the “Receive Data” push button is pressed, the firmware will start sending data to the demonstration program, all other controls are disabled until the “Stop Receiving Data” push button is pressed.
Figure 3 provides a flow chart for the operation of the firmware.
The firmware consists of an interrupt service routine (ISR) that receives commands from the demonstration GUI and sets the demo state based on those commands. A switch statement in the main loop evaluates the state.
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Figure 2. MAXREFDES131 GUI flowchart.
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Figure 3. MAXREFDES131 Firmware flowchart.
Figure 4. Master selection for mbed demo program.
1-Wire is a registered trademark of Maxim Integrated Products, Inc.
Arduino is a registered trademark of Arduino LLC.
ARM and mbed are registered trademarks of ARM Holdings.
Grid-EYE is a registered trademark of Panasonic Corporation.
Windows is a registered trademark and registered service mark of Microsoft Corporation.