Electronic Design

Synapse Sports SNAP

Synapse’s claim to fame is the Synapse Network Appliance Protocol (SNAP). It is implemented on its RF Engine ZigBee module that is also found on the Synapse Coordinator and End Devices. A set of four are found in the EK 1500 I tested. They can be powered by a pair of AA batteries. There is no patch area, but the modules have an interesting complement of interfaces including a fused relay connection. It can handle sensor inputs as well sensors (temperature, etc.) built onto the board. There is a two-digit LED display but only one extra switch. The RF Engine includes the 802.15.4 transceiver and a microcontroller, but like many ZigBee modules, programmers deal with the network through a serial interface with an AT-style text command sequence. The module handles the heavy lifting including coordination with other nodes in the network. The wireless network is self-forming and handled by the module. The RF Engines can handle external SMA antennas. An embedded F antenna is available as well. The system includes a 10dB receive amplifier standard but the system can consume as little as 47 µA. The on-chip microcontroller exposes an 8-channel, 10-bit A/D and 5 GPIO pins. The serial interface can also support RS-232 including handshake signals. This can be very useful when dealing with legacy hardware equipped with RS-232 connections. Flash memory for the microcontroller comes in 16Kbyte, 32Kbyte and 60Kbyte versions. AT Your Service Checking out the system is extremely quick because it utilizes the AT-style command set. The first step, though, is actually using the built-in demos and Windows-based host application. The latter provides logging and control support out of the box. It is simply a matter of installing software and turning on the hardware. It is possible to do quite a bit with the sample application and hardware as is, but things get more interesting when an external device is controlling the RF Engine using the AT command set. The description for the command set fits on a couple pages and includes simple sequences like:
AT MAC ?
to get the RF Engine to return the MAC address. Modules can be setup to send information when it detects an event so typically a module is setup and left to its own devices. The platform is not as flexible when it comes to moving larger amounts of data like packets from one node to another. It is ideal, though, for polling or forwarding a byte or two when an event occurs. If the application falls into the latter arena then the RF Engine is worth a look. It will likely be quick since the evaluation process with be quick as well and likely successful the first time. Related Links Synapse

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