Peripheral Board ID Memory

Board identification is handled courtesy of a DS2406 device (from Dallas Semiconductor). Although the device is actually a dual-addressable switch, it is used for the additional 1kbit of memory that it possesses.

Figure 1. Example 1-Wire memory
device used to contain the ident
code for the board.

The DS2406 is a 1-Wire® compatible device, primarily used to contain a code with which to identify the peripheral board when plugged in. The NanoTalk Controller interrogates this device over a single wire, the associated signal of which depends on where the peripheral board is attached:

• ONE_WIRE_PB_IDA – if attached to the 'PERIPHERAL BOARD A' connector.

• ONE_WIRE_PB_IDB – if attached to the 'PERIPHERAL BOARD B' connector.

• ONE_WIRE_PB_IDC – if attached to the 'PERIPHERAL BOARD C' connector.

 
The DS2406 supports half-duplex communication at a rate of up to 16.3kbits/s. Although power for the device is sourced over the same single wire as the data itself – courtesy of a parasitic capacitor which charges when the 1-Wire bus signal line is High – the device is also fed from the peripheral board's 3.3V supply, to ensure continuous power.

Similar devices on all peripheral boards and 3-connector daughter boards allow the NanoTalk Controller to detect which specific boards are available to the system.

Location on Board

The DS2406 device (designated U1_ID) is located on the solder side of the board, to the bottom-left of the 100-way docking connector.
 

Schematic Reference

The 1-Wire memory device can be found on sheet 1WB_DS2406_EPROM.SchDoc (entitled 1-Wire Bus ID) of the peripheral board schematics.

Further Device Information

For more information on the DS2406 device, refer to the datasheet (DS2406.pdf) available at www.maxim-ic.com.