As a byproduct of the PiDP-11 console support, I’ve defined a more or less ‘standard’ pin layout for the 40-pin connector on most of the Intel/Altera/Terasic FPGA boards – obviously carrying all the signals for the console itself, but also for the most basic peripherals that all PDP2011 systems need: a serial port for the console, an additional serial port, and the SPI interface signals for the Ethernet chip and the sd card for a disk. Basic, for sure, but also more than enough for enjoying the PDP-ness, and all of it conveniently fits on the 40 pins.
In the history of PDP2011, I’ve been using jumper wires to make all the required connections. That was easy enough with the older boards, as those usually had serial port and card connectors already – so mostly only some debugging stuff or the PMODNIC100 needed to be hooked up. But, DE0Nano was already a bit more of a challenge – mostly because there weren’t enough power pins to make direct connections to several PMODs. And then the console… well, the Raspberry Pi marketplace does have 40-pin jumper cables, those do come in handy. But, I’m thinking about a standard peripheral board to connect FPGA board, console panel, serial ports, sd card, and the PMODNIC100 together.
So far, I’ve set up the standard pin layout for three boards – obviously DE0Nano, but also DE10-Lite and DE0-CV. Like so:

To de0nano pin de10lite pin de0cv pin connector pin
rx1 PIN_T9 PIN_V10 PIN_H16 1
tx1 PIN_F13 PIN_W10 PIN_A12 2
rx2 PIN_R9 PIN_V9 PIN_H15 3
tx2 PIN_T15 PIN_W9 PIN_B12 4
panel_row[1] PIN_T14 PIN_V8 PIN_A13 5
panel_row[2] PIN_T13 PIN_W8 PIN_B13 6
panel_col[2] PIN_R13 PIN_V7 PIN_G17 7
rts1 PIN_T12 PIN_W7 PIN_D13 8
xu_debug 9
cts1 PIN_T11 PIN_V5 PIN_G17 10
VCC5 11
GND 12
panel_col[1] PIN_T10 PIN_W5 PIN_G14 13
sdcard_miso PIN_R11 PIN_AA15 PIN_J18 14
panel_xled[2] PIN_P11 PIN_AA14 PIN_J19 15
panel_xled[3] PIN_R10 PIN_W13 PIN_G11 16
panel_col[8] PIN_N12 PIN_W12 PIN_H10 17
panel_xled[4] PIN_P9 PIN_AB13 PIN_J11 18
sdcard_sclk PIN_N9 PIN_AB12 PIN_H14 19
sdcard_cs PIN_N11 PIN_Y11 PIN_A15 20
sdcard_mosi PIN_L16 PIN_AB11 PIN_J13 21
panel_xled[5] PIN_K16 PIN_W11 PIN_L8 22
panel_col[9] PIN_R16 PIN_AB10 PIN_A14 23
panel_col[6] PIN_L15 PIN_AA10 PIN_B15 24
panel_col[7] PIN_P15 PIN_AA9 PIN_C15 25
panel_col[5] PIN_P16 PIN_Y8 PIN_E14 26
panel_col[3] PIN_R14 PIN_AA8 PIN_G18 27
xu_mosi PIN_N16 PIN_Y7 PIN_E16 28
VCC3.3 29
GND 30
panel_col[4] PIN_N15 PIN_AA7 PIN_F14 31
panel_col[10] PIN_P14 PIN_Y6 PIN_G15 32
panel_col[11] PIN_L14 PIN_AA6 PIN_G16 33
xu_cs PIN_N14 PIN_Y5 PIN_F12 34
xu_miso PIN_M10 PIN_AA5 PIN_G16 35
panel_row[0] PIN_L13 PIN_Y4 PIN_G15 36
panel_col[0] PIN_J16 PIN_AB3 PIN_G13 37
panel_xled[0] PIN_K15 PIN_Y3 PIN_G12 38
xu_sclk PIN_J13 PIN_AB2 PIN_J17 39
panel_xled[1] PIN_J14 PIN_AA2 PIN_K16 40

The actual pin layout and the signals that go on the connector are already pretty much fixed – I’d like of course to be able to add more, like RTS/CTS ¬†for the second serial port, but there aren’t enough pins and I don’t see which others I could take out – except maybe xu_debug, but that’s only one. What I am still thinking about is to make a small PCB that connects everything together; but there is a surprising number of details to consider. I should probably do my next post on that subject.
Meantime, I’m working on a new sd card controller that will support SDHC cards, finally!

One Comment

Peter Allan March 31, 2019

I am really interested to see these developments, especially the SDHC card support. I have a PiDP-8i, but not yet a PiDP-11. This might convince me to get one.