Although I got the LTP-305HR dot-matrix LED multiplexing working, it doesn’t look anywhere near as nice as the original HP 5082-7340 or TI TIL311 hexadecimal displays. I’ve decided to drop my original plan to use the LTP-305HR displays, and use the hexadecimal displays instead. Broadcom (previously Avago, previously Agilent, previously HP) does still make similar hexadecimal displays, though without the red filter. They are quite pricey.
I’ve focused on getting the schematic and PCB layout done so that I can order PCBs this week. The switch PCB and switch bezel PCB are only minor tweaks to some I made last year, so those are ready. I’ve got the main board layout nearly completed; I need to add one electrolytic capacitor for bulk bypass, and one 14-pin header for configuration and/or expansion. Here’s an image of the not-quite-complete layout:
The board will accept either the HP 5082-7340 or TI TIL311 displays, using interleaved footprints. The board can be stuffed with just the traditional two digit data display, or can additionally have a four digit address display.
The I/O ports are a USB port (providing JTAG programming and a virtual UART) on the Cmod-A7 FPGA board, a MicroSD card, a TIA-232-F serial port, and an RCA jack for monochrome composite video.