The RHD recording system uses a standard interface cable and connector scheme to transmit serial digital data and power over distances of several meters using the Serial Peripheral Interface (SPI) protocol.

The following RHD SPI cables are available from Intan Technologies:

• RHD 3-ft (0.9 m) standard SPI cable (Part #C3203)
• RHD 6-ft (1.8 m) standard SPI cable (Part #C3206)
• RHD 1-ft (0.3 m) ultra thin SPI cable (Part #C3211)
• RHD 3-ft (0.9 m) ultra thin SPI cable (Part #C3213)
• RHD 6-ft (1.8 m) ultra thin SPI cable (Part #C3216)

Multiple cables may be daisy chained to span lengths of several meters (see table below).

Technical Specs	standard SPI cable	ultra thin SPI cable
connector type	Omnetics PZN-12 polarized nano
connector size	4.5 mm x 4.3 mm x 2.0 mm
color	blue	violet
cable diameter	2.9 mm	1.8 mm
cable mass	2.5 g/ft 8.2 g/m	1.2 g/ft 4.1 g/m
outer jacket material	0.013" thermoplastic elastomer (TPE)	0.013" silicone rubber
maximum cable length (16ch or 32ch headstage)	33 ft (9.9 m)	33 ft (9.9 m)
maximum cable length (2x32ch or 64ch headstage)	30 ft (9.0 m)	30 ft (9.0 m)
maximum cable length (2x64ch or 128ch headstage)	21 ft (6.3 m)	12 ft (3.6 m)

The RHD dual headstage adapter (Part #C3442) connects two RHD headstages to a single SPI cable, enabling high-density recording modules with up to 128 total channels. The adapter is approximately 8.7 cm long and weighs 1.9 g.

An SPI cable should be plugged into the center connector and RHD headstages attached to the left and right connectors, as shown below right. All RHD headstages except the 128-channel headstage are compatible with this device.

Use of this adapter with daisy-chained SPI interface cables exceeding 6 feet (1.8 meters) in total length may require a minor modification of one amplifier board to maintain high fidelity of the digital data. These technical details are discussed in the RHD dual headstage adapter datasheet.

The RHD SPI cable adapter board (Part #C3430) connects to an SPI cable and brings out all 12 power and data wires to 0.1" pitch solder holes for easy access. This board may be used to interface RHD SPI cables with prototype devices. It may also be used to connect RHD SPI signals to a commutator, as described in the application note, Adapting RHD SPI cables to a commutator (see Supporting Documents below).

Technical details on the SPI cables and connectors may be found in the RHD SPI cable/connector specification (see Supporting Documents below).