CPC CPLINK v1.0 Construction
Refer also to the photographs in the gallery below to see the the final board build.
All components except for the Co-processor connector (HDR2) are fitted to the top side of the PCB as shown in the photograph and in the Eagle PCB image below. The co-processor connector should be mounted on the back of the card for direct mounting of a RaspberryPi Zero.
All ICs should preferably be mounted in sockets. Take care to align all ICs in the correct orientation.
WARNING - do NOT fit a link on J2 if providing external power to the co-processor.
Note that the connector on the bottom edge should be a right-angled type (as listed in the BOM) to be able to plug into any of the backplane solutions.
PCBs are available directly from SeeedStudio's gallery pages.
A complete Bill of Materials is provided at Digi-key.
All parts with their Digi-Key reference codes and indicative pricing are listed in the table below, but simply clocking on the link above will build a shopping card at Digi-Key for you with all components already there.
| Index | Quantity | Part Number | Manufacturer Part Number | Description | Unit Price | Extended Price GBP |
|---|---|---|---|---|---|---|
| 1 | 1 | 1528-2831-ND | 4079 | 2X20 SOCKET RISER HEADER FOR RPI | 1.58 | £1.58 |
| 2 | 11 | 399-4329-ND | C322C104K5R5TA | CAP CER 0.1UF 50V X7R RADIAL | 0.116 | £1.27 |
| 3 | 1 | S1011EC-40-ND | PRPC040SAAN-RC | CONN HEADER VERT 40POS 2.54MM | 0.53 | £0.53 |
| 4 | 4 | AE9992-ND | A 16-LC-TT | CONN IC DIP SOCKET 16POS TIN | 0.2 | £0.80 |
| 5 | 1 | 296-9251-5-ND | CD74HCT126E | IC BUF NON-INVERT 5.5V 14DIP | 0.49 | £0.49 |
| 6 | 4 | 296-2117-5-ND | CD74HCT40105E | IC FIFO REGISTER 4X16 16DIP | 0.67 | £2.68 |
| 7 | 2 | AE9998-ND | A 20-LC-TT | CONN IC DIP SOCKET 20POS TIN | 0.23 | £0.46 |
| 8 | 2 | P15803CT-ND | EEA-GA1E220H | CAP ALUM 22UF 20% 25V RADIAL | 0.22 | £0.44 |
| 9 | 1 | 296-2157-5-ND | CD74HCT4075E | IC GATE OR 3CH 3-INP 14DIP | 0.73 | £0.73 |
| 10 | 2 | 296-41545-5-ND | CD74HCT27E | IC GATE NOR 3CH 3-INP 14DIP | 0.49 | £0.98 |
| 11 | 2 | 296-8503-5-ND | SN74LVC245AN | IC TXRX NON-INVERT 3.6V 20DIP | 0.48 | £0.96 |
| 12 | 1 | 296-2111-5-ND | CD74HCT30E | IC GATE NAND 1CH 8-INP 14DIP | 0.33 | £0.33 |
| 13 | 5 | AE9989-ND | A 14-LC-TT | CONN IC DIP SOCKET 14POS TIN | 0.18 | £0.90 |
| 14 | 2 | S9344-ND | SPC02SVJN-RC | CONN JUMPER SHORTING .100" GOLD | 0.11 | £0.22 |
| 15 | 1 | 3M157291-ND | 30350-5002HB | CONN HEADER R/A 50POS 2.54MM | 0.9 | £0.90 |
| Subtotal | £12.70 | |||||
| VAT | £2.54 | |||||
| Total | £15.24 |
The co-processor header, HDR2, provided in the BOM is a female socket intended to allow a RaspberryPi Zero with a male pin header to be mounted directly on the back of the card. Other connectors may be used and can be front or back mounted for use with other co-processors. The pin-out described on the main wiki page details the pin names as viewed from the front (IC side) of the card.
Jumper J2 is the power connector for HDR2, allowing the FIFO card to power the coprocessor. These pins can instead be replaced with a Schottky diode, anode connected to the FIFO board 5V supply (lower pin) and cathode connected to the HDR2 (upper pin). Using a Schottky eliminates any electrical issues when power is supplied both to the FIFO board and to the co-processor separately. However, when the FIFO board is used to power the co-processor there will be approximately 450mV drop over this diode, so the co-processor will receive only 4.5V rather than the full 5V.
All programs and data files in this project are made available under the terms of the GNU General Public License v3.
Top View of assembled card
Rear View of assembled card - note Pi connector attached to the rear
Rear View of assembled card with RaspberryPi Zero in place