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Move LWL python script to tools/lwl and add README.txt

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Alan C. Assis 2021-01-15 17:34:52 -03:00 committed by Xiang Xiao
parent f40389b359
commit f62ff8d938
2 changed files with 92 additions and 57 deletions
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89
tools/lwl/README.txt Normal file
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Console over Lightweight Link
=============================
LWL is a Lightweight bidirectional communication between target and debug host
without any need for additional hardware.
It works with openOCD and other debuggers that are capable of reading and
writing memory while the target is running...it should run with JLink
for example, if you've got the SDK and modify this file accordingly.
Principle of operation is simple; An 'upword' of 32 bits communicates
from the target to the host, a 'downword' of the same size runs in the
opposite direction. These two words can be in any memory that is
read/write access for both the target and the debug host. A simple ping
pong handshake protocol over these words allows up/down link communication.
On the upside no additional integration is needed. On the downside it may be
necessary to feed lwl with cycles to poll for changes in the downword,
depending on the use case. For the case of a simple console, that's not
needed.
For convenience these communication locations are automatically discovered
from the RAM by searching through it. Just define downwordaddr and
upwordaddr if you want to work with fixed locations.
Bit configuration
-----------------
Downword (Host to target);
A D U VV XXX O2 O1 O0
A 31 1 - Service Active (Set by host)
D 30 1 - Downsense (Toggled when there is data)
U 29 1 - Upsense ack (Toggled to acknowledge receipt of uplink data)
VV 28-27 2 - Valid Octets (Number of octets valid in the message)
XXX 26-24 3 - Port in use (Type of the message)
O2 23-16 8 - Octet 2
O1 15-08 8 - Octet 1
O0 07-00 8 - Octet 0
Upword (Target to Host);
A 31 1 - Service Active (Set by device)
D 30 1 - Downsense ack (Toggled to acknowledge receipt of downlink data)
U 29 1 - Upsense (Toggled when there is data)
VV 28-27 2 - Valid upword octets
XXX 26-24 3 - Port in use (Type of the message)
O2 23-16 8 - Octet 2
O1 15-08 8 - Octet 1
O0 07-00 8 - Octet 0
Port 1 is used for Console. No other ports are currently defined.
Usage
=====
No special python modules are needed, it should be possible to run the
application simply as shown below;
------------------------------------------
$ ./ocdconsole.py
==Link Activated
nsh>
nsh> help
help usage: help [-v] [<cmd>]
? echo exit hexdump ls mh sleep xd
cat exec help kill mb mw usleep
nsh>
------------------------------------------
This code is designed to be 'hardy' and will survive a shutdown and
restart of the openocd process. When your target application
changes then the location of the upword and downword may change,
so they are re-searched for again. To speed up the start process
consider putting those words at fixed locations (e.g. via the
linker file) and referencing them directly.
Future work/Improvements
========================
Currently the lwl driver on NuttX side is doing polling, but for
better performance it could use interrupts to detect when the memory
position was modified to read the data.
It also will avoid using busy waiting inside the driver, look at
nuttx/arch/arm/src/common/arm_lwl_console.c for more information.

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tools/ocdconsole.py → tools/lwl/ocdconsole.py
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#!/usr/bin/env python3
# tools/ocdconsole.py
# tools/lwl/ocdconsole.py
#
# Copyright (C) 2019 Dave Marples. All rights reserved.
# Author: Dave Marples <dave@marples.net>
@ -32,62 +32,8 @@
# POSSIBILITY OF SUCH DAMAGE.
#
#
# Console over Lightweight Link
# =============================
#
# LWL is a Lightweight bidirectional communication between target and debug host
# without any need for additional hardware.
#
# It works with openOCD and other debuggers that are capable of reading and
# writing memory while the target is running...it should run with JLink
# for example, if you've got the SDK and modify this file accordingly.
#
# Principle of operation is simple; An 'upword' of 32 bits communicates
# from the target to the host, a 'downword' of the same size runs in the
# opposite direction. These two words can be in any memory that is
# read/write access for both the target and the debug host. A simple ping
# pong handshake protocol over these words allows up/down link communication.
# On the upside no additional integration is needed. On the downside it may be
# necessary to feed lwl with cycles to poll for changes in the downword,
# depending on the use case. For the case of a simple console, that's not
# needed.
#
# For convenience these communication locations are automatically discovered
# from the RAM by searching through it. Just define downwordaddr and
# upwordaddr if you want to work with fixed locations.
#
#
# Bit configuration
# -----------------
#
# Downword (Host to target);
#
# A D U VV XXX O2 O1 O0
#
# A 31 1 - Service Active (Set by host)
# D 30 1 - Downsense (Toggled when there is data)
# U 29 1 - Upsense ack (Toggled to acknowledge receipt of uplink data)
# VV 28-27 2 - Valid Octets (Number of octets valid in the message)
# XXX 26-24 3 - Port in use (Type of the message)
# O2 23-16 8 - Octet 2
# O1 15-08 8 - Octet 1
# O0 07-00 8 - Octet 0
#
# Upword (Target to Host);
#
# A 31 1 - Service Active (Set by device)
# D 30 1 - Downsense ack (Toggled to acknowledge receipt of downlink data)
# U 29 1 - Upsense (Toggled when there is data)
# VV 28-27 2 - Valid upword octets
# XXX 26-24 3 - Port in use (Type of the message)
# O2 23-16 8 - Octet 2
# O1 15-08 8 - Octet 1
# O0 07-00 8 - Octet 0
#
# Port 1 is used for Console. No other ports are currently defined.
#
# Use
# ===
# Usage
# =====
#
# No special python modules are needed, it should be possible to run the
# application simply as shown below;