From e672b9d0c6b4886f4f37695da90da744343e1ee7 Mon Sep 17 00:00:00 2001
From: Vladimir Burian <buriavl2@fel.cvut.cz>
Date: Sun, 17 Apr 2011 12:58:08 +0200
Subject: [PATCH] GPIO and qcount MCU peripherals added

---
 mcu_periph/gpio.vhd           | 68 +++++++++++++++++++++++++++++++++++
 mcu_periph/qcounter_mcu16.vhd | 59 ++++++++++++++++++++++++++++++
 2 files changed, 127 insertions(+)
 create mode 100644 mcu_periph/gpio.vhd
 create mode 100644 mcu_periph/qcounter_mcu16.vhd

diff --git a/mcu_periph/gpio.vhd b/mcu_periph/gpio.vhd
new file mode 100644
index 0000000..795ffca
--- /dev/null
+++ b/mcu_periph/gpio.vhd
@@ -0,0 +1,68 @@
+library ieee;
+use ieee.std_logic_1164.all;
+use ieee.std_logic_arith.all;
+
+--------------------------------------------------------------------------------
+
+entity gpio is
+  generic (
+    W : integer := 8);                  -- GPIO port width (pin count)
+  port (
+    -- Peripheral bus interface
+    ACK_O  : out std_logic;
+    ADR_I  : in  std_logic_vector (1 downto 0);
+    CLK_I  : in  std_logic;
+    DAT_I  : in  std_logic_vector (W-1 downto 0);
+    DAT_O  : out std_logic_vector (W-1 downto 0);
+    RST_I  : in  std_logic;
+    SEL_I  : in  std_logic;
+    STB_I  : in  std_logic;
+    WE_I   : in  std_logic;
+    -- GPIO port pins
+    GPIO_I : in  std_logic_vector (W-1 downto 0);
+    GPIO_O : out std_logic_vector (W-1 downto 0));
+end gpio;
+
+--------------------------------------------------------------------------------
+
+architecture behavioral of gpio is
+
+  signal gpio_output     : std_logic_vector (W-1 downto 0) := (others => '0');
+  signal gpio_output_new : std_logic_vector (W-1 downto 0);
+  signal write_en        : std_logic;
+  
+begin
+  
+  ACK_O <= SEL_I and STB_I;
+
+  with ADR_I select
+    DAT_O <=
+    GPIO_I          when "00",
+    gpio_output     when "01",
+    (others => '-') when others;
+
+  
+  with ADR_I select
+    gpio_output_new <=
+    DAT_I                     when "01",
+    gpio_output or DAT_I      when "10",
+    gpio_output and not DAT_I when "11",
+    gpio_output               when others;
+  
+  write_en  <= SEL_I and STB_I and WE_I;
+  
+  process (CLK_I, RST_I) is
+  begin
+    if rising_edge(CLK_I) then
+      if RST_I = '1' then
+        gpio_output <= (others => '0');
+      else
+        if write_en = '1' then
+          gpio_output <= gpio_output_new;
+        end if;        
+      end if;
+    end if;
+  end process;
+
+end behavioral;
+
diff --git a/mcu_periph/qcounter_mcu16.vhd b/mcu_periph/qcounter_mcu16.vhd
new file mode 100644
index 0000000..85da77a
--- /dev/null
+++ b/mcu_periph/qcounter_mcu16.vhd
@@ -0,0 +1,59 @@
+library ieee;
+use ieee.std_logic_1164.ALL;
+use ieee.std_logic_arith.ALL;
+
+--------------------------------------------------------------------------------
+
+entity qcounter_mcu16 is
+  port (
+    -- Peripheral bus interface
+    ACK_O  : out std_logic;
+    ADR_I  : in  std_logic;
+    CLK_I  : in  std_logic;
+    DAT_O  : out std_logic_vector (15 downto 0);
+    SEL_I  : in  std_logic;
+    STB_I  : in  std_logic;
+    -- QCounter component interface
+    QCOUNT : in  std_logic_vector (31 downto 0));
+end qcounter_mcu16;
+
+--------------------------------------------------------------------------------
+
+architecture behavioral of qcounter_mcu16 is
+
+  -- When reading whole 32-bit qcount input, first QCNTL has to be loaded, because
+  -- this event causes QCNTH to latch appropriate value of QCOUNT. This procedure
+  -- ensures that correct value is read.
+
+  -- Register of upper 16 bits of QCOUNT input.
+  signal upper_qcount : std_logic_vector (15 downto 0);
+  signal read_en      : std_logic;
+  
+--------------------------------------------------------------------------------
+
+begin
+
+  ACK_O <= read_en;
+  
+  with ADR_I select
+    DAT_O <=
+    QCOUNT (15 downto 0) when '0',
+    upper_qcount         when '1',
+    (others => 'X')      when others;
+
+  read_en <= SEL_I and STB_I;
+
+  
+  -- Upper qcounter register
+  QCNTH : process (CLK_I)
+  begin
+    if rising_edge(CLK_I) then
+      if read_en = '1' then
+        upper_qcount <= QCOUNT (31 downto 16);
+      end if;
+    end if;
+  end process;
+
+
+end behavioral;
+
-- 
2.39.2