June 29, 2018
I recently came into possession of a Apple IIe (an enhanced Apple II from the early 80’s) and decided to build a few PCB’s to help get this old warhorse back up in running. The first board designed was an extender card for the Apples expansion card to make testing and fault finding them a little easier. The second PCB was a prototyping board to allow me to build up various test circuits.
Both will be available on Tindie soon
April 24, 2018
I got a bumper box of PCB’s in the post today, just in time for Maker Faire UK 2018 this weekend (29th/30t April 2018).
Inside the box were some new RC2014 boards. The first two new PCB’s were my respins of a Z80 SIO/2 serial board and a Raspberry Pi Zero terminal board, as well as two brand new designs.
The first brand new board was a RC2014 RS232 breakout board allowing TxD1/RxD1 and/or TxD2/RxD2 serial signals from the RC2014 bus to be driven at RS232 levels.
The second brand new PCB was a new 8052 CPU board. This is a bit of an experimenters board as the 8052 bus architecture doesn’t directly map onto the Z80 bus architecture. When using the 8052 CPU some of the Z80 control bus signals (!M1, !MREQ, !IORQ etc.) will need pulling low via jumpers when attempting to make use of other cards. So why all the fuss. Well, the 8052 CPU does have the excellent the 8052-BASIC available which does make it a fun and a powerful (in 1980/1990 micro terms 🙂 ) system.
January 28, 2018
I’ve been busy with my big box of PCBs and I here’s my first Z80 system design and build. It comprises of the following:
– Z80 CPU card
– 8K ROM & 8K SRAM card
– 68B50 ACIA card
– 5-slot enhanced+ backplane
It’s pretty much a standard Z80 layout but I’ve expanded the bus to the latest Enhanced Bus definition for all the cards. The 5-slot backplane uses double row (2×39) female pin headers to include the RC2014 enhanced bus and in addition I’ve added an extra set of address lines (A16 to A23) for the possibility of using 16-bit CPU’s (8086/68000) and memory options (upto 1MB) in the future.
Here’s some pics of the various cards:
ACIA UART Card
December 27, 2017
Christmas came slightly early this year when a big box of PCB’s arrived.
Inside the box where a bunch of PCB’s for making guitar effects boards.
As well as a bunch of PCB’s for my take on a RC2014 Z80 based retro computing system.
More pics to follow when I’ve built them up.
February 25, 2017
Following on from last months post about my SoB DB9 breakout board I’ve design a few of more SoB breakout boards using the DP5050 footprint.
The first is a 2-channel Relay Board. It has two relays with LED’s to indicate when they are active. Using it is pretty easy as it features the choice of screw terminals or pin headers to interface to it.
The next is a universal RS232 breakout. I call it universal as all the pins (8 in total but not ground) from a 9-way RS232 DB9 are broken out onto pin headers. To connect up to these are the 4 signals (T1,T2,R1 and R2) from a MAX232 (or equivalent) RS232 chip. So you can swap around the transmit and receive and handshake signals as you like.
The next board is just a classic prototyping board. There’s not much too say about this board.
The last board is a symmetric power supply for rectify AC voltage into positive and negative DC supply rails. I’m hoping to use this for a audio project I’ve got in the works.
Dangerous Prototypes (DP) have a great page describing the various PCB sizes here:
As usual you can find them on my Tindie page here
January 9, 2017
Whilst looking to build some breakout boards I remembered the Sick of Beige (SoB) “standard” of PCB footprints designed by Dangerous Prototypes. DP have made a really cool set of PCB footprints in various sizes with the added bonus of being designed to be case friendly.
Dangerous Prototypes have a great page describing the various PCB sizes here:
My first Sick of Beige (SoB) board is SoB DB9, using the DP5050 footprint. This is a handy little breakout board for those wanting to build their own 9-way D-Type interfaces be it for RS232, RS485, CAN bus or any other project.
A standard 9-way D-Type (Male) connector provides the interface with 3.5mm Screw Terminals connections provided for easy interfacing. In addition a Male Pin Header connections is also provided. Two small circuit prototyping areas are also provided.
– 9-Pin D-Type connector (Male)
– Easy to Connect Headers
– 3.5mm Screw Terminals
– 2.54mm Pin Header
– small circuit prototyping area x2
– Compatible with Sick of Beigh DP5050 footprint
– Board Dimensions: 50 x 50 mm
– 3.2mm Mounting Holes x4
– Industrial Control
As usual you can find them on my Tindie page here
November 22, 2016
Despite USB being everywhere, I still use a lot of industrial and embedded interfaces, such as RS232 and RS485 interfaces, in my projects. Legacy equipment especially and even new industrial equipment still use RS232 for programming and monitoring. While RS485 interfaces can still be found a lot in industrial communications such as factory automation.
So with this in mind I felt I needed an Raspberry Pi add-on board to simplify a lot of these connections. So here is the Raspberry PIIO FieldBus add-on board. It is a multi-communications board RS232 or RS485 and CAN Bus interfaces.
The board uses 3.3V components and is completely voltage compatible with the Raspberry Pi.
The board connects directly to the Raspberry Pi’s SPI to provide CAN Bus communications and also to the UART Rx and Tx to provide RS232 or RS485 communications.
CAN Bus interface uses MCP2515 CAN controller and MCP2551 CAN transceiver IC provides CAN Bus v2.0 A/B at 1 Mb/s. It is connected the Pi’s SPI Interface. Connection is provided via a 3-Way screw terminals.
RS232 interface uses a 3.3V MAX3232 (or Equivalent IC) chip and CTS (GPIO16) & RTS (GPIO17) signals are provided. Connection is provided via an industry standard 9-Way D Connector (Male).
RS485 interface uses 3.3V MAX3485 (or Equivalent IC) chip with DE (GPIO27) & !RE (GPIO22) used to control the RS485 transceiver control signals. Connection is provided via a 3-Way screw terminals to the outside world.
The Raspberry Pi expansion port has only on UART interface available for serial communications. So where both circuits are fitted, only one RS232 or one RS485 interface may be connected to the UART, therefore only one interface can be used at any time.
You can find them on our Tindie store