GPIA pinout needs normalization to better support generic PMOD interfaces.

This is also a breaking change. At this point, we need to support a GPIA-2 core.

e Emulator Changes (phase 1)

[ ] Drive activity LED from SDSS signal.
[ ] Create a GPIA-2 with a 64-bit I/O port, and a 64-bit data direction register.
[ ] Assign PMOD port 0/1 pins as in table below.

eForth Changes

[ ] Remove support for driving LED signal.
[ ] Switch code to use GPIA-2 I/O registers and bit assignments.

e Emulator Changes (phase 2)

[ ] Remove support for GPIA-1.

Documentation Changes

[ ] Create GPIA-2 preliminary datasheet.

PMOD 0/1 pin assignments.

The table below lists the pinouts and the corresponding GPIA I/O register bit assignments. Neither of these pinouts conform to established PMOD interface types. However, SPI-mode is closest to type-2 but with some modifications. Thus, I'll declare SPI-mode type 2C. However, SD/MMC-mode is unique, and should be given its own type, which I'll declare arbitrarily as type 7, since the highest official specification is type 6.

Port Bit	PMOD Pin	Direction (SPI)	Role (SPI)	Direction (SD)	Role (SD)
0	1	Out	SDSS	I/O	SDDAT3
1	2	Out	SDMOSI	Out	SDCMD
2	3	In	SDMISO	I/O	SDDAT0
3	4	Out	SDCLK	Out	SDCLK
	5		GND		GND
	6		3V3		3V3
4	7	Out	not used	I/O	SDDAT1
5	8	Out	not used	I/O	SDDAT2
6	9	In	SDCD	In	SDCD
7	10	In	SDWP	In	SDWP
	11		GND		GND
	12		3V3		3V3

More generically, the I/O port bit to 1x6 PMOD assignments are as follows:

63:60	59:56	55:52	51:48	47:44	43:40	39:36	35:32	31:28	27:24	23:20	19:16	15:12	11:8	7:4	3:0
15	14	13	12	11	10	9	8	7	6	5	4	3	2	1	0

Not all FPGA development boards support all PMODs. Some drivers may elect to use pairs of adjacent 1x6 PMODs to drive a 2x6 PMOD interface. Unless documented otherwise, and unless there's a good reason, 2x6 PMODs must start on an even-numbered slot.

KestrelComputer / kestrel