84PCE:Ports:D000

Synopsis

Port Number: D000

Memory-mapped Address: F80000

Function: LCD Interface

This appears to be an FTSSP010 or compatible SPI controller that interfaces with the LCD. The command set seems to closely match the Sitronix ST7789 family [1].

Port	Default	Bits	Information
D000 F80000		0000F38C	CR0: Boot code writes 180B/09 before/after turning on/off the lcd.
D004 F80004	0000182B	007FFFFF	CR1: Boot code initializes to 02000B. Bits 0-15 are clock divider - 1, bits 16-23 are data length - 1, and bits 24-31 are padding length.
D008 F80008	0002000B	00000F8F	CR2: Boot code initializes to 010C. Bit 0 is set to transfer data. Bit 7 is set/reset for reading/writing.
D00C F8000C		000007F6	Status bits. Bit 2 is set if data is being sent or received and bits 12-15 are the number of bits queued. Boot code waits for bits 2 and 12-15 to be 0 before/after reading/writing.
D010 F80010	00002100		Interrupt control.
D014 F80014	00000008		Interrupt status.
D018 F80018			FIFO in/out.
D01C F8001C	0E0F0F1F		Inside reserved range. Appears to be a copy of the feature register at D064.
D060 F80060	00012100		Revision (read-only)
D064 F80064	0E0F0F1F		Features (read-only): 32-bit data width, 16-bit FIFOs, list of extra protocols supported.

Known Commands

Hex Defaults	Command	Details
01	Software Reset
10 10	Enable Sleep Mode	Turns pixels black, low power mode?
11 11	Disable Sleep Mode
12	Enable Partial Mode	Resets vertical scrolling start to 0.
13	Disable Partial Mode	Also disables vertical scrolling mode and resets vertical scrolling start to 0.
20	Uninvert Colors
21	Invert Colors
26 <8:GC> 26 00 26 02	Set Gamma	Selects between 4 preset gamma curves: Valid values are 1, 2, 4, 8, invalid values appear to use 1.
28	Turn Off Display	Turns all pixels white.
29 29	Turn On Display	Restore GRAM pixels.
2A <BE16:StartCol> <BE16:EndCol> 2A 0000 013F	Set Window Columns	Set the pixel update window from StartCol to EndCol inclusive.
2B <BE16:StartLine> <BE16:EndRow> 2B 0000 00EF	Set Window Rows	Set the pixel update window from StartRow to EndRow inclusive.
30 <BE16:StartRow> <BE16:EndRow>	Set Partial Area Rows	Only displays from StartRow to EndRow inclusive, other lines white.
33 <BE16:TopArea> <BE16:ScrollArea> <BE16:BottomArea>	Vertical Scrolling Definition	TopArea/BottomArea are static (non-scrolling) line counts before and after the ScrollArea whose value is ignored.
36 <8:MAC> 36 08	Memory Address Control	Bit 2: Horizontal Refresh Order Bit 3: BGR Order Bit 4: Vertical Refresh Order Bit 5: Column Major Update Bit 6: Column Update Order Bit 7: Row Update Order
37 <BE16:VSP>	Vertical Scrolling Start Position	First line of ScrollArea starts at this GRAM line.
38	Disable Idle Mode	Restore 18bpp mode.
39	Enable Idle Mode	3bpp 8 color mode (only uses msb of each color component).
3A ? 3A 66	Interface Pixel Format	Upper and lower nibbles are modes for the two interfaces: 3 is 12bpp, 5 is 16bpp, 6 is 18bpp (msb is ignored, invalid uses 18bpp).
B0 ? ? B0 11 F0	Interface Control	First Param: Bit 0: Use lcd controller clocks instead of internal clocks. Bit 4: Get GRAM data from lcd controller instead of spi interface. Bit 7: Bypass GRAM and output directly to lcd. Second Param: Polarity of clocks?
B1 ? ? ? B1 01 05 14 B1 01 15 14	Unknown?
B2 ? ? ? ? ? B2 0C 0C 00 33 33	Unknown?
B7 ? B7 35	Unknown?
BB ? BB 17 BB 1B	Unknown?
C0 ? C0 2C C0 22	Unknown?
C2 ? C2 01	Unknown?
C3 ? C3 03 C3 15	Unknown?
C4 ? C4 20	Unknown?
C6 ? C6 0F	Unknown?
D0 ? ? D0 AF A1	Unknown?
D2 ? D2 00	Unknown?
DC	Unknown?	One parameter "read" and checked if equal to 0x35, but reading doesn't appear to work in the first place...
E0 ? ? ? ? ? ? ? ? ? ? ? ? ? ? E0 D0 00 00 10 0F 1A 2D 54 3F 3B 18 17 13 17 E0 D0 00 00 10 0F 1A 2D 54 3F 3B 18 17 13 17	Positive Gamma Correction	Definitely affects gamma, parameters unknown and don't match docs.
E1 ? ? ? ? ? ? ? ? ? ? ? ? ? ? E1 D0 00 00 10 0F 09 2B 43 40 3B 18 17 13 17 E1 D0 00 00 10 0F 09 2B 43 40 3B 18 17 13 17	Negative Gamma Correction	Definitely affects gamma, parameters unknown and don't match docs.
E9 ? ? ? E9 08 08 08	Unknown?
EB	Something!
F0	Gamma?
F1	Gamma?
F2	Gamma?

Example

Sending

 ld a,036h ; Flips the lcd horizontally, vertically, and swaps the b and r components
 call spiCmd
 ld a,0C0h
 call spiParam

 ld a,002h ; Resetting the lcd on exit
 call spiCmd
 jp boot_InitializeHardware

; Input: A = parameter
spiParam:
 scf ; First bit is set for data
 .db 030h ; jr nc,? ; skips over one byte
; Input: A = command
spiCmd:
 or a,a ; First bit is clear for commands
 ld hl,0F80818h
 call spiWrite
 ld l,h
 ld (hl),001h
spiWait:
 ld l,00Dh
spiWait1:
 ld a,(hl)
 and a,0F0h
 jr nz,spiWait1
 dec l
spiWait2:
 bit 2,(hl)
 jr nz,spiWait2
 ld l,h
 ld (hl),a
 ret
spiWrite:
 ld b,3
spiWriteLoop:
 rla
 rla
 rla
 ld (hl),a ; send 3 bits
 djnz spiWriteLoop
 ret

Receiving

This does not appear to work, always returning 0 on the calcs I've tested, due to either a TI bug or hardware issue.

; Input: A = command
; Ouput: A = data
spiRead:
 ld hl,0F80808
 ld (hl),00Ch
 ld l,018h
 or a,a
 call spiWrite
 xor a,a ; not sure what this is for
 call spiWrite
 ld l,009h
 ld (hl),001h
 dec l
 ld (hl),081h
 call spiWait
 ld l,$18
 ld a,(hl) ; dummy read
 ld a,(hl)
 ld a,(hl) ; Why is there no wait after dummy read?
 ld a,(hl)
 rla
 rla
 rla
 rla
 rla
 and a,0E0h
 ld c,a
 ld a,(hl)
 rla
 rla
 and a,01Ch
 or a,c
 ld c,a
 ld a,(hl)
 rra ; why are we throwing away the lsb instead of the msb
 and a,003h
 or a,c
 ret