VGA framebuffer connections

common/csrbase.h

@@ -6,5 +6,6 @@
 #define ID_BASE		0xe0001000
 #define TIMER0_BASE	0xe0001800
 #define MINIMAC_BASE	0xe0002000
+#define FB_BASE		0xe0002800
 
 #endif /* __CSRBASE_H */

constraints.py

@@ -1,5 +1,5 @@
 class Constraints:
-	def __init__(self, crg0, norflash0, uart0, ddrphy0, minimac0):
+	def __init__(self, crg0, norflash0, uart0, ddrphy0, minimac0, fb0):
 		self.constraints = []
 		def add(signal, pin, vec=-1, iostandard="LVCMOS33", extra=""):
 			self.constraints.append((signal, vec, pin, iostandard, extra))
@@ -16,6 +16,7 @@ class Constraints:
 		add(crg0.flash_rst_n, "P22", extra="SLEW = FAST | DRIVE = 8")
 		add(crg0.trigger_reset, "AA4")
 		add(crg0.phy_clk, "M20")
+		add(crg0.vga_clk_pad, "A11")
 		
 		add_vec(norflash0.adr, ["L22", "L20", "K22", "K21", "J19", "H20", "F22",
 			"F21", "K17", "J17", "E22", "E20", "H18", "H19", "F20",
@@ -61,6 +62,13 @@ class Constraints:
 		add(minimac0.phy_col, "W20")
 		add(minimac0.phy_crs, "W22")
 		
+		add_vec(fb0.vga_r, ["C6", "B6", "A6", "C7", "A7", "B8", "A8", "D9"])
+		add_vec(fb0.vga_g, ["C8", "C9", "A9", "D7", "D8", "D10", "C10", "B10"])
+		add_vec(fb0.vga_b, ["D11", "C12", "B12", "A12", "C13", "A13", "D14", "C14"])
+		add(fb0.vga_hsync_n, "A14")
+		add(fb0.vga_vsync_n, "C15")
+		add(fb0.vga_psave_n, "B14")
+		
 		self._phy_rx_clk = minimac0.phy_rx_clk
 		self._phy_tx_clk = minimac0.phy_tx_clk
 

milkymist/framebuffer/__init__.py

@@ -0,0 +1,19 @@
+from migen.fhdl.structure import *
+
+class Framebuffer:
+	def __init__(self, csr_address, asmiport):
+		# VGA clock input
+		self.vga_clk = Signal()
+		
+		# pads
+		self.vga_psave_n = Signal()
+		self.vga_hsync_n = Signal()
+		self.vga_vsync_n = Signal()
+		self.vga_sync_n = Signal()
+		self.vga_blank_n = Signal()
+		self.vga_r = Signal(BV(8))
+		self.vga_g = Signal(BV(8))
+		self.vga_b = Signal(BV(8))
+
+	def get_fragment(self):
+		return Fragment()

milkymist/m1crg/__init__.py

@@ -19,7 +19,9 @@ class M1CRG:
 			"clk4x_wr_strb",
 			"clk4x_rd",
 			"clk4x_rd_strb",
-			"phy_clk"
+			"phy_clk",
+			"vga_clk",
+			"vga_clk_pad"
 		]:
 			s = Signal(name=name)
 			setattr(self, name, s)

top.py

@@ -5,7 +5,8 @@ from migen.fhdl.structure import *
 from migen.fhdl import verilog, autofragment
 from migen.bus import wishbone, wishbone2asmi, csr, wishbone2csr, dfi
 
-from milkymist import m1crg, lm32, norflash, uart, sram, s6ddrphy, dfii, asmicon, identifier, timer, minimac3
+from milkymist import m1crg, lm32, norflash, uart, sram, s6ddrphy, dfii, asmicon, \
+	identifier, timer, minimac3, framebuffer
 from cmacros import get_macros
 from constraints import Constraints
 
@@ -75,6 +76,7 @@ def get():
 	#
 	asmicon0 = asmicon.ASMIcon(sdram_phy, sdram_geom, sdram_timing)
 	asmiport_wb = asmicon0.hub.get_port()
+	asmiport_fb = asmicon0.hub.get_port()
 	asmicon0.finalize()
 	
 	#
@@ -122,12 +124,14 @@ def get():
 	uart0 = uart.UART(csr_offset("UART"), clk_freq, baud=115200)
 	identifier0 = identifier.Identifier(csr_offset("ID"), 0x4D31, version, int(clk_freq))
 	timer0 = timer.Timer(csr_offset("TIMER0"))
+	fb0 = framebuffer.Framebuffer(csr_offset("FB"), asmiport_fb)
 	csrcon0 = csr.Interconnect(wishbone2csr0.csr, [
 		uart0.bank.interface,
 		dfii0.bank.interface,
 		identifier0.bank.interface,
 		timer0.bank.interface,
-		minimac0.bank.interface
+		minimac0.bank.interface,
+		#fb0.bank.interface
 	])
 	
 	#
@@ -144,8 +148,14 @@ def get():
 	#
 	crg0 = m1crg.M1CRG(50*MHz, clk_freq)
 	
-	frag = autofragment.from_local() + interrupts + ddrphy_clocking(crg0, ddrphy0)
-	cst = Constraints(crg0, norflash0, uart0, ddrphy0, minimac0)
+	vga_clocking = Fragment([
+		fb0.vga_clk.eq(crg0.vga_clk)
+	])
+	frag = autofragment.from_local() \
+		+ interrupts \
+		+ ddrphy_clocking(crg0, ddrphy0) \
+		+ vga_clocking
+	cst = Constraints(crg0, norflash0, uart0, ddrphy0, minimac0, fb0)
 	src_verilog, vns = verilog.convert(frag,
 		cst.get_ios(),
 		name="soc",

verilog/m1crg/m1crg.v

@@ -23,7 +23,11 @@ module m1crg #(
 	output clk4x_rd_strb,
 	
 	/* Ethernet PHY clock */
-	output reg phy_clk
+	output reg phy_clk,	/* < unbuffered, to I/O */
+	
+	/* VGA clock */
+	output vga_clk,		/* < buffered, to internal clock network */
+	output vga_clk_pad	/* < forwarded through ODDR2, to I/O */
 );
 
 /*
@@ -190,5 +194,45 @@ BUFG bufg_x1(
 /* Ethernet PHY */
 always @(posedge pllout4)
 	phy_clk <= ~phy_clk;
+
+/* VGA clock */
+// TODO: hook up the reprogramming interface
+DCM_CLKGEN #(
+	.CLKFXDV_DIVIDE(2),
+	.CLKFX_DIVIDE(4),
+	.CLKFX_MD_MAX(2.0),
+	.CLKFX_MULTIPLY(2),
+	.CLKIN_PERIOD(0.0),
+	.SPREAD_SPECTRUM("NONE"),
+	.STARTUP_WAIT("FALSE")
+) vga_clock_gen (
+	.CLKFX(vga_clk),
+	.CLKFX180(),
+	.CLKFXDV(),
+	.LOCKED(),
+	.PROGDONE(),
+	.STATUS(),
+	.CLKIN(pllout4),
+	.FREEZEDCM(1'b0),
+	.PROGCLK(1'b0),
+	.PROGDATA(),
+	.PROGEN(1'b0),
+	.RST(1'b0)
+);
+
+ODDR2 #(
+	.DDR_ALIGNMENT("NONE"),
+	.INIT(1'b0),
+	.SRTYPE("SYNC")
+) vga_clock_forward (
+	.Q(vga_clk_pad),
+	.C0(vga_clk),
+	.C1(~vga_clk),
+	.CE(1'b1),
+	.D0(1'b1),
+	.D1(1'b0),
+	.R(1'b0),
+	.S(1'b0)
+);
  
 endmodule