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    /spi_master_slave/trunk/syn
    from Rev 5 to Rev 6
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Rev 5 → Rev 6

/spi_master.vhd
60,8 → 60,8
-- PARALLEL READ INTERFACE
-- =======================
-- An internal buffer is used to copy the internal shift register data to drive the 'do_o' port. When a complete word is received,
-- the core shift register is transferred to the buffer, at the rising edge of the spi clock, 'spi_2x_clk_i'.
-- The signal 'do_valid_o' is set one 'spi_2x_clk_i' clock after, to directly drive a synchronous memory or fifo write enable.
-- the core shift register is transferred to the buffer, at the rising edge of the spi clock, 'spi_clk'.
-- The signal 'do_valid_o' is set one 'spi_clk' clock after, to directly drive a synchronous memory or fifo write enable.
-- 'do_valid_o' is synchronous to the parallel interface clock, and changes only on rising edges of 'pclk_i'.
-- When the interface is idle, data at the 'do_o' port holds the last word received.
--
68,11 → 68,11
-- PARALLEL READ SEQUENCE
-- ======================
-- ______ ______ ______ ______
-- spi_2x_clk_i bit1 \______/ bitN \______/bitN-1\______/bitN-2\__... -- spi 2x base clock
-- spi_clk bit1 \______/ bitN \______/bitN-1\______/bitN-2\__... -- spi 2x base clock
-- _ __ __ __ __ __ __ __ __
-- pclk_i \__/ \__/ \__/ \__/ \__/ \__/ \__/ \__/ \_... -- parallel interface clock (may be async to sclk_i)
-- _____________ _____________________________________... -- 1) rx data is transferred to 'do_buffer_reg'
-- do_o ___old_data__X__________new_data___________________... -- after last rx bit, at rising 'spi_2x_clk_i'.
-- do_o ___old_data__X__________new_data___________________... -- after last rx bit, at rising 'spi_clk'.
-- ____________
-- do_valid_o ____________________________/ \_________... -- 2) 'do_valid_o' strobed for 2 'pclk_i' cycles
-- -- on the 3rd 'pclk_i' rising edge.
88,26 → 88,26
------------------------------ COPYRIGHT NOTICE -----------------------------------------------------------------------
--
-- This file is part of the SPI MASTER/SLAVE INTERFACE project http://opencores.org/project,spi_master_slave
--
--
-- Author(s): Jonny Doin, jdoin@opencores.org
--
--
-- Copyright (C) 2011 Authors and OPENCORES.ORG
-- --------------------------------------------
--
-- This source file may be used and distributed without restriction provided that this copyright statement is not
-- --------------------------------------------
--
-- This source file may be used and distributed without restriction provided that this copyright statement is not
-- removed from the file and that any derivative work contains the original copyright notice and the associated
-- disclaimer.
--
-- disclaimer.
--
-- This source file is free software; you can redistribute it and/or modify it under the terms of the GNU Lesser
-- General Public License as published by the Free Software Foundation; either version 2.1 of the License, or
-- (at your option) any later version.
--
-- This source is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied
-- warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public License for more
-- details.
--
-- (at your option) any later version.
--
-- This source is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied
-- warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public License for more
-- details.
--
-- You should have received a copy of the GNU Lesser General Public License along with this source; if not, download
-- it from http://www.opencores.org/lgpl.shtml
-- it from http://www.opencores.org/lgpl.shtml
--
------------------------------ REVISION HISTORY -----------------------------------------------------------------------
--
132,7 → 132,7
-- frequency sequential circuits, to preserve clocking resources and avoid path delay glitches.
-- 2011/07/10 v1.00.0098 [JD] implemented SCK clock divider circuit to generate spi clock directly from system clock.
-- 2011/07/10 v1.10.0075 [JD] verified spi_master_slave in silicon at 50MHz, 25MHz, 16.666MHz, 12.5MHz, 10MHz, 8.333MHz,
-- 7.1428MHz, 6.25MHz, 1MHz and 500kHz. The core proved very robust at all tested frequencies.
-- 7.1428MHz, 6.25MHz, 1MHz and 500kHz. The core proved very robust at all tested frequencies.
--
-----------------------------------------------------------------------------------------------------------------------
-- TODO
143,7 → 143,7
library ieee;
use ieee.std_logic_1164.all;
use ieee.numeric_std.all;
use ieee.std_logic_unsigned.all;
use ieee.std_logic_unsigned.all;
 
--================================================================================================================
-- There are several output ports that are used to simulate and verify the core operation.
169,10 → 169,10
spi_mosi_o : out std_logic; -- spi bus mosi output
spi_miso_i : in std_logic := 'X'; -- spi bus spi_miso_i input
di_req_o : out std_logic; -- preload lookahead data request line
di_i : in std_logic_vector (N-1 downto 0) := (others => 'X'); -- parallel data in (clocked on rising spi_2x_clk_i after last bit)
di_i : in std_logic_vector (N-1 downto 0) := (others => 'X'); -- parallel data in (clocked on rising spi_clk after last bit)
wren_i : in std_logic := 'X'; -- user data write enable, starts transmission when interface is idle
do_valid_o : out std_logic; -- do_o data valid signal, valid during one spi_2x_clk_i rising edge.
do_o : out std_logic_vector (N-1 downto 0); -- parallel output (clocked on rising spi_2x_clk_i after last bit)
do_valid_o : out std_logic; -- do_o data valid signal, valid during one spi_clk rising edge.
do_o : out std_logic_vector (N-1 downto 0); -- parallel output (clocked on rising spi_clk after last bit)
--- debug ports: can be removed for the application circuit ---
do_transfer_o : out std_logic; -- debug: internal transfer driver
wren_o : out std_logic; -- debug: internal state of the wren_i pulse stretcher
189,10 → 189,10
 
--================================================================================================================
-- this architecture is a pipelined register-transfer description.
-- all signals are clocked at the rising edge of the system clock 'spi_2x_clk_i'.
-- all signals are clocked at the rising edge of the system clock 'sclk_i'.
--================================================================================================================
architecture rtl of spi_master is
-- core clocks, generated from 'spi_2x_clk_i': initialized to differential values
-- core clocks, generated from 'sclk_i': initialized to differential values
signal core_clk : std_logic := '0'; -- continuous core clock, positive logic
signal core_n_clk : std_logic := '1'; -- continuous core clock, negative logic
signal core_ce : std_logic := '0'; -- core clock enable, positive logic
262,20 → 262,20
-- GENERICS CONSTRAINTS CHECKING
--=============================================================================================
-- minimum word width is 8 bits
assert N >= 8
report "Generic parameter 'N' (shift register size) needs to be 8 bits minimum"
assert N >= 8
report "Generic parameter 'N' (shift register size) needs to be 8 bits minimum"
severity FAILURE;
-- minimum prefetch lookahead check
assert PREFETCH >= 2
report "Generic parameter 'PREFETCH' (lookahead count) needs to be 1 minimum"
assert PREFETCH >= 2
report "Generic parameter 'PREFETCH' (lookahead count) needs to be 1 minimum"
severity FAILURE;
-- maximum prefetch lookahead check
assert PREFETCH <= N-5
report "Generic parameter 'PREFETCH' (lookahead count) out of range, needs to be N-5 maximum"
assert PREFETCH <= N-5
report "Generic parameter 'PREFETCH' (lookahead count) out of range, needs to be N-5 maximum"
severity FAILURE;
-- SPI_2X_CLK_DIV clock divider value must not be zero
assert SPI_2X_CLK_DIV > 0
report "Generic parameter 'SPI_2X_CLK_DIV' must not be zero"
assert SPI_2X_CLK_DIV > 0
report "Generic parameter 'SPI_2X_CLK_DIV' must not be zero"
severity FAILURE;
 
--=============================================================================================
295,7 → 295,7
-- Each phase is selected so that all the registers can be clocked with a rising edge on all SPI
-- modes, by a single high-speed global clock, preserving clock resources.
-----------------------------------------------------------------------------------------------
-- generate the core clock enables from the serial high-speed input clock
-- generate the 2x spi base clock enable from the serial high-speed input clock
spi_2x_ce_gen_proc: process (sclk_i) is
variable clk_cnt : integer range SPI_2X_CLK_DIV-1 downto 0 := 0;
begin
310,7 → 310,7
end if;
end process spi_2x_ce_gen_proc;
-----------------------------------------------------------------------------------------------
-- generate the core antiphase clocks and clock enables.
-- generate the core antiphase clocks and clock enables from the 2x base CE.
core_clock_gen_proc : process (sclk_i) is
begin
if sclk_i'event and sclk_i = '1' then
353,7 → 353,7
samp_ce <= core_n_ce;
end generate;
-----------------------------------------------------------------------------------------------
-- FSM clock generation: generate 'fsm_ce' from core_ce or core_n_ce depending on CPHA
-- FSM clock enable generation: generate 'fsm_ce' from core_ce or core_n_ce depending on CPHA
fsm_ce_cpha_0_proc :
if CPHA = '0' generate
begin
/readme.txt
1,6 → 1,9
SPI_MASTER_ATLYS
================
 
This is a ISE 13.1 project to test the spi_master.vhd model in silicon.
 
The target board is a Digilent Atlys board (Spartan-6 @ 100MHz), and the circuit was tested at different SPI clock frequencies.
The target board is a Digilent Atlys FPGA board (Spartan-6 @ 100MHz), and the circuit was tested at different SPI clock frequencies.
 
See the scope screenshots in the spi_master_scope_photos.zip file for each SPI frequency tested.
 
7,6 → 10,7
This circuit also includes a very robust debouncing circuit to use with multiple inputs. The model, "grp_debouncer.vhd" is also published under a LGPL license.
 
The files are:
-------------
 
spi_master.vhd vhdl model for the spi_master interface
grp_debouncer.vhd vhdl model for the switch debouncer
28,3 → 32,4
 
Jonny Doin
jdoin@opencores.org
 

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