Minispartan3 UART debugging

main.cc

#include <stdio.h>
#include <stdlib.h>
#include <xio.h>
#include <xiomodule.h>
#include <xparameters.h>

XIOModule xio;

int main()
{
	// Start GPIO
	XIOModule_Initialize(&xio, XPAR_IOMODULE_0_DEVICE_ID);
	microblaze_register_handler(XIOModule_DeviceInterruptHandler, XPAR_IOMODULE_0_DEVICE_ID);
	XIOModule_Start(&xio);

	// Turn on LEDs to show we are alive
	XIOModule_DiscreteWrite(&xio, 1, 0x3);

	// Print out a status message,
	xil_printf("Hello World!\r\n");
	while( true ) {
		unsigned char cmd = XIOModule_RecvByte(STDIN_BASEADDRESS);
		xil_printf("CMD: 0x%x\r\n", cmd);
	}
}

pins.ucf

NET "CLK_32MHZ" LOC = P85;
NET "LEDS<0>" LOC = P20;
NET "LEDS<1>" LOC = P19;
NET "LEDS<2>" LOC = P16;
NET "UART_RX" LOC = P88;
NET "UART_TX" LOC = P86;

top.vhd

library IEEE;
use IEEE.STD_LOGIC_1164.ALL;
entity top is
	port (
		-- LED outputs
		LEDS : out std_logic_vector(2 downto 0);
		
		-- Built-in oscillator
		CLK_32MHz : in std_logic;
		
		-- UART pins to talk to FT2232D chip, which sends over USB
		UART_RX : in std_logic;
		UART_TX : out std_logic
	);
end top;

architecture Behavioral of top is
	component softcore
		port (
			Clk : in std_logic;
			Reset : in std_logic;
			UART_Rx : in std_logic;
			UART_Tx : out std_logic;
			GPO1 : out std_logic_vector(31 DOWNTO 0)
		);
	end component;

	-- Signal to link GPO1 to LEDs
	signal GPO1 : std_logic_vector(31 downto 0);
begin

	-- Instantiate our softcore
	mcs : softcore
		port map (
			Clk => CLK_32MHz,
			UART_Rx => UART_RX,
			UART_Tx => UART_TX,
			RESET => '0',
			GPO1 => GPO1
		);

	-- Tie GPO1 signal to LEDs
	LEDS <= GPO1(2 downto 0);
end Behavioral;