Cascade temperature sensor

Description

The cascade temperature sensor from Homechip Ltd overcomes one of the problems in building 1-wire networks, that is how to determine the serial numbers of each sensor in the network.

The cascade sensor uses the Maxim DS28EA00 chip to enable the 1-wire controller to probe the network in topological order and hence to discover the network layout without the need to read and record the serial number of every sensor prior to installation.

The DS28EA00 is a digital thermometer with 9-bit (0.5°C) to 12-bit (1/16°C) resolution and alarm function with nonvolatile (NV), user-programmable upper and lower trigger points. Each DS28EA00 has its unique 64-bit registration number that is factory-programmed into the chip. Data is transferred serially through the 1-Wire® protocol, which requires only one data line and a ground for communication. The improved 1-Wire front end with hysteresis and glitch filter enables the DS28EA00 to perform reliably in large 1-Wire networks. Unlike other 1-Wire thermometers, the DS28EA00 has two additional pins to implement a sequence detect function. This feature allows the user to discover the registration numbers according to the physical device location in a chain, e.g., to measure the temperature in a storage tower at different height. If the sequence detect function is not needed, these pins can be used as general-purpose input or output.

The cascade sensor is easy to wire up, with screw terminals providing access to the 1-wire data and ground signals, and to the sequence pins. There is also an optional power supply for larger networks where parasitic power is not enough. The Cascade sensor has an inbuilt voltage regulator allowing the power to be supplied at any voltage between 5 - 15v, making it especially suitable for automotive applications.

The cascade sensor is supplied mounted in a robust ABS case with vent holes top and bottom to allow rapid temperature stabilisation. Cables can enter and leave through supplied grommets at either end, for ease of wiring.