SC147 is a modular backplane section with RC2014 compatible 40-pin bus sockets.

• SC147 – Assembly guide
• SC147 – Compatibility
• SC147 – Parts list
• SC147 – Printed circuit board
• SC147 – Support
• SC147 – User guide
• SC147 – 3D printed mounting rails at thingiverse.com

Downloads

• SC147 – Gerber files (ZIP)
• SC147 – Kit contents sheet (PDF)
• SC147 – Schematic v1.0 (PDF)

Suppliers

Kits	Website	From	Currency
Small Computers Direct	SCDirect	UK	GBP
Stephen C Cousins	Tindie	UK	USD
PCBs	Website	From	Currency
Small Computers Direct	SCDirect	UK	GBP
Stephen C Cousins	Tindie	UK	USD
Assembled and Tested	Website	From	Currency
Not available
Components
See parts list

Description

SC147 is a modular backplane designed for the RC2014 bus.

The main features of this design are:

• 6 vertical RC2014 bus compatible sockets (40-pin)
• 1 horizontal RC2014 bus compatible socket (40-pin)
• Use stand-alone with power from serial or SC142
• Extension for SC114, SC130, SC133, SC671, SC673, etc.
• Expandable with additional modular backplane sections
• User pins (U1 to U4) and serial pins (TX and RX) can be isolated by cutting thin tracks on the underside of the PCB.

User Guide

SC147 is a modular backplane designed for the RC2014 bus.

This modular backplane section can be used standalone or used to extend another modular backplane, such as SC133, or motherboard with a horizontal bus socket, such as SC114 or SC130.

When used to extend a modular backplane or motherboard, power will usually be supplied from the other backplane section or the motherboard.

When used standalone, power must be supplied from a module plugged into one of the module sockets, or from the backplane’s 40-pin male header pins (the 40-pin “plug”). Most serial modules offer the option of connecting power. This allows the whole system to be powered from an FTDI style USB to serial adapter – if there is sufficient power available. Alternatively, you can use the SC142 power module.

Module sockets

The backplane has 6 vertical and 1 horizontal RC2014 bus compatible 40-pin module sockets. RC2014 bus compatible modules can be connected to any of these sockets.

It should be noted that modules designed for the enhanced RC2014 bus, which have a partial second row of pins, may not work with 40-pin bus sockets, or may work with limitations. Similarly, modules designed for extended RC2014 style bus systems, such as the 80-pin bus, may not work.

The horizontal bus socket allows a module to be connected horizontally which can make access easier during development or debugging. In addition, this socket allows the backplane to be extended by connecting additional modular backplane sections.

Option links

It may be desirable to isolate some signals on the backplane. This might be necessary if you have, for example, two serial modules, each linked to its own terminal module. This setup would require the signals between the first serial module and its terminal module, to be isolated from the signals between the second pair of modules.

These are the isolation links as seen on the bottom of the printed circuit board:

Short row	Long row
	TX
	RX
User 1	User 1
User 2	User 2
User 3	User 3
User 4	User 4

Parts List

Reference	Qty	Component
PCB	1	SC147, v1.0, PCB
C1 to C7	7	Capacitor, ceramic, 100 nF
P1	1	Header, male, 1 row x 40 pin, angled, type B profile or Header, male, 2 row x 40 pin, angled The second row of pins needs to be removed. See the assembly guide for details.
S1 to S6	6	Header, female, 1 row x 40 pin, straight
S7	1	Header, female, 1 row x 40 pin, angled
Spacer	6	Spacer, 10mm, M3, nylon
Screw (for spacer)	6	Machine screw, 6mm, M3
Optional items
Feet	6	Self-adhesive feet (alternative to spacers above)
JP1, JP3, JP5	3	Header, male, 2 x 6 pin, straight
JP2, JP4, JP6	3	Header, male, 2 x 4 pin, straight
Jumper shunts	30	Jumper shunts

Printed Circuit Board

Links

SC147, v1.0, PCB only (Tindie)

SC147, v1.0, Complete kit (Tindie)

SC147, v1.0, PCB design files (OSHWLab)

SC147, v1.0, Gerber files (ZIP)

Assembly Guide

Experienced builders can just go ahead and populate the board. There shouldn’t be any surprises to catch you out.

Introduction

This guide assumes you are familiar with assembling circuit boards, soldering, and cleaning. If not, it is recommended you read some of the guides on the internet before continuing.

First check you have all the required components, as listed in the parts list.

Before assembling it is worth visually inspecting the circuit board for anything that looks out of place, such as mechanical damage or apparent manufacturing defects.

If you have a multimeter that measures resistance or has a continuity test function, check there is not a short on the power supply tracks. Connect the probes to each terminal of one of the capacitors, such as C1. This should be an open circuit, not a short circuit.

The picture below shows what a completed SC147, modular backplane should look like.

Bus socket (horizontal)

Bus plug (horizontal)

Either fit a type B profile 1-row of 40-pins angled header or a modified 2-rows of 40-pins angled header.

If the bus header plug is a modified 2-row angled male header, the second row needs to be removed. A modified 2-row header is used instead of a single row header as the pin position matches the single row socket, as illustrated below, while the common single row header does not. Single and double row headers, and how to modify them, is explained here.

Capacitors 100 nF (0.1 µF)

The exact value of this component is not critical. The use of very cheap capacitors within the range of about 30 to 200 nF is acceptable.

Bus sockets (vertical)

Quick Tests

Repeat the check made earlier for a short on the power supply tracks. Connect the meter probes to either end of one of the capacitors. This should be an open circuit, not a short circuit. If you are using a digital meter set to measure resistance it will likely take a few seconds for the reading to stabilise as there are now capacitors on the power lines. A reading of more than 100 kΩ (100000 ohms) is acceptable.

Optional

The backplane includes a set of isolation points between the module sockets, as shown below. These allow some signals to be isolated between modules.

The PCB is manufactured with thin tracks linking these isolation points such that these signals are connected to all the module sockets. If you wish to isolate some signals it is necessary to cut the appropriate thin track on the solder side of the PCB.

The table below shows the signals that can be isolated.

Label	Signal name
TX	Serial transmit (output from a serial module)
RX	Serial receive (input to a serial module)
U1	User #1
U2	User #2
U3	User #3
U4	User #4

Should you wish to reconnect the signals you can solder a link in the appropriate place. Alternatively, you can solder header pins and use jumper shunts to connect the required signals.

Inspection

Remove any solder ‘splats’ with a brush, such as an old toothbrush.

Visually inspect the soldering for dry joints and shorts.

Clean the flux off with suitable cleaning materials.

Visually inspect again.

Compatibility

This backplane conforms to the RCBus specification v1.0 for 40-pin systems. Namely, RCBus-2014 standard bus.

The RCBus specification includes RCBus-2014 (both RC2014 standard 40-pin bus and RC2014 enhanced 60-pin bus) and also the full 80-pin RCBus. The 80-pin RCBus provides support for advanced Z80 features, such as the interrupt daisy-chain, as well as support for other processor families.

Notes

• This design is made in accordance with the “designed for RC2014” labelling scheme.
• RC2014 is a trademark of RFC2795 Ltd.
• This product is designed for hobby use and is not suitable for industrial, commercial, or safety-critical applications.
• The product contains small parts and is not suitable for young children.