Peripheral Board 1-Wire Communications

The NB2DSK01 provides a 1-Wire® serial bus (ONE_WIRE_DB_PB), which is connected from its daughter board connector through to each of its peripheral board connectors. This provides the ability to communicate directly from a processor in an FPGA design, with one or more slave 1-Wire compatible devices located across plugged-in peripheral boards (where such devices exist). As the 1-Wire bus is made available to all three peripheral board sites it allows development of a dedicated network of 1-Wire devices – a micro-LAN if you will.

The peripheral board provides a 1-Wire device socket for insertion of a single 1-Wire device of your choice.

Figure 1. 3-pin socket ready
to accommodate a 1-Wire
device.

The socket is 3-pin, 1.27mm pitch. Pin 2 of the socket is wired to the ONE_WIRE_DB_PB signal line – corresponding to the DATA line of an inserted 1-Wire device.

Pins 1 and 3 of the socket are connected via 0Ω resistors to Ground. These resistors can be modified, as required, to suit future design requirements.

Location on Board

The 1-Wire device socket (labeled '1-WIRE' and designated J7) is located on the component side of the board.

Schematic Reference

The 1-Wire device socket can be found on sheet PB_ExtenderPlug.SchDoc (entitled PB Extender Board Socket) of the peripheral board schematics.

Design Interface Component

Table 1 summarizes the available design interface component that can be placed from the FPGA NB2DSK01 Port-Plugin.IntLib, for access to the 1-Wire bus and subsequent communication with an inserted 1-Wire slave device.

Further Device Information

For a high-level overview of the 1-Wire bus protocol, refer to the application note (AN3989.pdf) available at www.maxim-ic.com.