mibuild: define memory card pins of the Milkymist One platorm

This patch adds the memory card pins to the M1 platform definition in
mibuild.

I've tentatively named them "mmc". As far as I can tell, "MMC" is not
trademarked ("MultiMediaCard" the new "eMMC" would be), and "MMC" is
commonly used in the industry in a descriptive way to refer to this
sort of interface.

The original Verilog-based M1 calls the interface "mc", but since
several names have changed between milkymist and -ng, I thought I'd
use a more familiar name.

Usage example (clock signal divided by powers of two on the MMC TPs):
https://github.com/wpwrak/ming-ddc-debug/blob/counter-on-mmc/build.py

- Werner

diff --git a/mibuild/platforms/m1.py b/mibuild/platforms/m1.py
index 5273441a9a3b2f0320270dcf43d97112f1cd55b2..cc29a02f18efef22dd9c8864902d29ae5d3f8f8b 100644 (file)
--- a/mibuild/platforms/m1.py
+++ b/mibuild/platforms/m1.py
@@ -83,6 +83,13 @@ _io = [
                IOStandard("LVCMOS33")
        ),
 
+       ("mmc", 0,
+               Subsignal("clk", Pins("A10")),
+               Subsignal("cmd", Pins("B18")),
+               Subsignal("dat", Pins("A18", "E16", "C17", "A17")),
+               IOStandard("LVCMOS33")
+       ),
+
        # Digital video mixer extension board
        ("dvi_in", 0,
                Subsignal("clk", Pins("A20")),