This is a dual micro-SD card plus Ethernet controller for the Amiga 500. The controller piggybacks on the odd CIA (CIA A) chip on the Amiga 500 motherboard.
The two Micro-SD cards are operated in SPI mode. Using the 68000 movep (move to/from peripheral) instruction the controller can read and write up to 450kB/s from and to the micro-SD card on a standard 7MHz 68000 CPU.
The primary channel is intended for internal use. This micro-SD card in this slot functions as a fixed harddisk. The secondary channel is intended to connect to an extension cable to hold a removable (hot-swappable) micro-SD card. For this purpose, proper measures are taken to control signal integrity over the extension cable. The controller can also handle any current surges that can occur during hot swapping without loading the Amiga power rail too much.
The Ethernet controller is a Microchip ENC28J60 device. This device supports a 10Mbit network connection. The interface is built in a slightly non-standard way to maximum immunity for external interference.
The Micro-SD cards are supported by sd-lide.device.
The Ethernet controller is supported by enc28j60.device.
On a standard Amiga 500 with a 7MHz 68000 CPU the following performance is reached:
- SysInfo reports 250kB/s read speed for the Micro-SD cards.
- The network reaches up to 22kB/s and is mostly limited by CPU speed.
Much better performance can be expected when a faster CPU is installed.
Proof that this was actually built:
And the obligatory SysInfo screenshot:
##Building Under releases you will find the latest gerbers, bill of materials, bitstream, etc. The files are in a format that is suitable for most well-known PCBA manufacturers. I would recommend having the boards soldered professionally. This project uses small compononent and especially the CPLD is not solderable by hand. I had the boards made with all the SMD parts and the ethernet connector mounted. I only soldered the pinheaders and the CIA socket myself. For the pinheaders that plug into the CIA socket on the A500 motherboard, be sure to use the THIN and ROUND (aka "turned") pinheaders. Otherwise the motherboard socket will be damaged.