I'm super happy to report that my latest design, the JRC-1, is up and running!
Attachment:
jrc1.jpg [ 123.91 KiB | Viewed 632 times ]
(apologies for the slightly blurry picture)
The board is 200x130 mm and four layers. It was manufactured by JLCPCB. The system specs are:
65c816 CPU @ 4 MHz
1 MB of 55 ns SRAM (2 x AS6C4008)
256 KB of 90 ns EEPROM (W29C020)
65c22 VIA
65SPI (ATF1504AS)
28C92 dual UART
CPLD glue logic (ATF1504AS)
Two DB-9 serial ports (via MAX238 drivers)
SD card port
User port exposing all VIA I/O lines plus SPI
JTAG port for reprogramming the CPLDs
Three forty-pin expansion connectors (not currently fitted)
Reset and NMI switches via DS1813s
DC barrel jack for 5V power
This is my third full (non-breadboard) build, and also my first one that required exactly
zero board changes to get working. That being said the layout is not 100% error-free: the footprints for the DS1813s are reversed (I misread the data sheet), and the expansion connector footprints are wrong. The only physical problem I ended up having is that my PLCC-44 sockets are a bit dodgy; next time I'll just order quality ones from Mouser.
The expansion connectors expose A0-A7, D0-D7, and some other necessary bus signals, plus four each +5V and GND. They will be used by me to prototype some add-on features that may end up on the main board of a future design. They are supposed to be 40-pin card edge connectors, but despite test fitting on paper I did not realize the spacing between pin rows is too narrow, and so for now I'm just going to use 2x20 pin headers.
Anyway I just wanted to share my joy at getting the build up and running so painlessly. Since the boards were not even scheduled to arrive for a few more days this is basically an early Christmas present to myself. Now I can spend my Christmas vacation working on the software side of things.