URL
https://opencores.org/ocsvn/wb4pb/wb4pb/trunk
Subversion Repositories wb4pb
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Rev 12 → Rev 13
/wb4pb/trunk/tools/baud_rate_calculator.tcl
0,0 → 1,118
################################################################################ |
## This sourcecode is released under BSD license. |
## Please see http://www.opensource.org/licenses/bsd-license.php for details! |
################################################################################ |
## |
## Copyright (c) 2010, Stefan Fischer <Ste.Fis@OpenCores.org> |
## All rights reserved. |
## |
## Redistribution and use in source and binary forms, with or without |
## modification, are permitted provided that the following conditions are met: |
## |
## * Redistributions of source code must retain the above copyright notice, |
## this list of conditions and the following disclaimer. |
## * Redistributions in binary form must reproduce the above copyright notice, |
## this list of conditions and the following disclaimer in the documentation |
## and/or other materials provided with the distribution. |
## * Neither the name of the author nor the names of his contributors may be |
## used to endorse or promote products derived from this software without |
## specific prior written permission. |
## |
## THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" |
## AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE |
## IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE |
## ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE |
## LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR |
## CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF |
## SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS |
## INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN |
## CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) |
## ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE |
## POSSIBILITY OF SUCH DAMAGE. |
## |
################################################################################ |
## filename: baud_rate_calculator.tcl |
## description: tcl-script generating assembler constants for standard baud |
## rates |
## todo4user: 1. modify output file path, SYSTEM_CLOCK and BAUD_RATES as needed |
## 2. run script with TCL interpreter of your choice, i. e. from |
## ModelSim (R) GUI: Menu->Tools->TCL->Execute Macro... |
## 3. copy and paste file content from generated |
## baud_rate_constants.txt to assembler source code |
## version: 0.0.0 |
## changelog: - 0.0.0, initial release |
## - ... |
################################################################################ |
|
# output file path |
cd "e:/home_users/ste.fis/projects/wb4pb/trunk/asm" |
|
# reference clock, normally several MHz |
set SYSTEM_CLOCK 50.0E6 |
|
# some standard baud rates |
set BAUD_RATES { |
300 |
600 |
1200 |
2400 |
4800 |
9600 |
19200 |
38400 |
57600 |
115200 |
230400 |
460800 |
921600 |
} |
|
# open file handle |
set f [open "baud_rate_constants.txt" w] |
|
# baud rate configuration: |
# baud_limit = round( system clock frequency / (16 * baud rate) ) - 1 |
# i. e. 9600 baud at 50 MHz system clock => |
# baud_limit = round( 50.0E6 / (16 * 9600) ) - 1 = 325 = 0x0145 |
|
# WARNING, baud rate error should not exceed 1.0 % for reliable operation! |
|
# calculating baud min. and max. values |
set baud_max [expr floor($SYSTEM_CLOCK / 16)] |
set baud_min [expr ceil($SYSTEM_CLOCK / (16 * 65536))] |
|
puts $f "; baud rate settings for $SYSTEM_CLOCK Hz system reference clock" |
puts $f "; max. $baud_max baud" |
puts $f "; min. $baud_min baud (16 bit baud timer)" |
foreach baud_rate $BAUD_RATES { |
# checking, if current baud rate works with system hardware parameters |
if {[expr $baud_min <= $baud_rate] && [expr $baud_rate <= $baud_max]} { |
# calculating hardware baud timer limit |
set baud_limit [expr round($SYSTEM_CLOCK / (16 * $baud_rate)) - 1] |
# calculating actual hardware baud rate |
set actual_baud_rate [expr $SYSTEM_CLOCK / (16 * ($baud_limit + 1))] |
# calculating baud rate error, value is commented out automatically, if |
# frequency error is greater than the recommended 1 % |
if { |
[set baud_error [expr abs(($baud_rate / $actual_baud_rate) - 1)]] > 0.01 |
} { |
set comment ";" |
} else { |
set comment "" |
} |
# generating a 16 bit, 4 character hexadecimal string of hardware baud timer |
# limit |
set baud_limit_hex [format %04X $baud_limit] |
# creating strings with constant definitions in kcpsm3 assembler syntax, |
# splitting into high and low byte |
puts $f "${comment}CONSTANT UART_BAUD_LO_${baud_rate}_VALUE , [string range\ |
$baud_limit_hex 2 3] ; actual baud rate [format %.2f \ |
$actual_baud_rate]" |
puts $f "${comment}CONSTANT UART_BAUD_HI_${baud_rate}_VALUE , [string range\ |
$baud_limit_hex 0 1] ; => baud rate error [format %.3f [expr 100 *\ |
$baud_error]] %" |
} |
} |
|
# closing file |
close $f |