From af95156e6cbc5c3be792b6bfd2aa1b31f1a00033 Mon Sep 17 00:00:00 2001 From: Kolja Waschk Date: Sun, 24 Feb 2008 21:15:43 +0000 Subject: [PATCH] Added section about link drivers (parport and usbconn) git-svn-id: https://urjtag.svn.sourceforge.net/svnroot/urjtag/trunk@1091 b68d4a1b-bc3d-0410-92ed-d4ac073336b7 --- jtag/ChangeLog | 2 ++ jtag/doc/UrJTAG.txt | 46 ++++++++++++++++++++++++++++++++++++++++++--- 2 files changed, 45 insertions(+), 3 deletions(-) diff --git a/jtag/ChangeLog b/jtag/ChangeLog index 32477429..118e5d7c 100644 --- a/jtag/ChangeLog +++ b/jtag/ChangeLog @@ -24,6 +24,8 @@ * src/tap/cable/jlink.c: New driver for Segger J-Link, Atmel SAM-ICE etc. based on usbconn link driver + * doc/UrJTAG.txt: Added section about link drivers + 2008-02-24 Eugene Boldenkov * src/bus/mpc824x.c: Add 32-bit bus support (1900847) diff --git a/jtag/doc/UrJTAG.txt b/jtag/doc/UrJTAG.txt index ecf5770b..b8ced9a4 100644 --- a/jtag/doc/UrJTAG.txt +++ b/jtag/doc/UrJTAG.txt @@ -316,7 +316,7 @@ Cygwin environment, first get it from: Unzip the CDM*.zip to some directory and tell UrJTAG about this directory during the configure step before actual compilation: - ./configure --with-libftd2xx=/cygdrive/c/windows/temp/CDM_Drivers + ./configure --with-ftd2xx=/cygdrive/c/windows/temp/CDM_Drivers All other USB JTAG adapters can be supported only if libusb is installed. There is a libusb-win32 variant that can be used in a Cygwin environment: @@ -959,8 +959,8 @@ src/tap:: Functions for accessing the chain in general === Drivers === - * Cable-specific drivers - * Parport drivers + * Cable drivers + * Link drivers * TAP drivers * Chain drivers * Bus drivers @@ -1137,6 +1137,46 @@ look at the code in src/tap/cable/generic.c, which contains generic routines, suitable for parallel port based cables (and some for other types of cables as well). +==== Link drivers ==== + +Link drivers like the "parport" driver collection provide the basis for +communication between cable driver and actual JTAG adapter. The openwince JTAG +tools supported only parallel port links with the "parport" drivers. UrJTAG +introduced support for USB links, but in the early releases the drivers for +these just mimic the parallel port links. + +The basic functions provided by all link drivers are + + * connect(), to called from cable driver connect() + * open(), to actually connect to the device during cable driver init() + * close(), to disconnect from the device during cable driver done() + * free(), to free all resources, called from cable driver free() + +===== parport ===== + +Currently there are parport drivers for direct access to the parallel port on a +PC using I/O addresses (direct.c), and for using ppdev on Linux or ppi on FreeBSD. + +In addition, there are "ftdi" and "ftd2xx" parport drivers that actually are for +communication with USB cables based on FTDI chips. They cannot be used for +connecting old parallel port cables through parallel to USB adapters with FTDI +chips, and probably soon will be rewritten as "usbconn" drivers instead. + +All parport drivers present a common API for setting and reading signals. + +===== usbconn ===== + +The usbconn drivers provide a common API to search for and connect with USB +devices. At the moment, there's only a libusb driver, but others will follow +(e.g. to communicate with FTDI chip based cables through libftdi and/or FTD2XX, +to communicate with Cypress FX2 using EZUSB.SYS or CyUSB.sys, and more). + +In contrast to the parport API, the usbconn drivers provide only the functions +for connecting, disconnecting, and for releasing ressources. The actual +communication must be implemented using the underlying library's functions, +e.g. usb_write from libusb, or ftdi_write from libftdi. Therefore, each driver +using usbconn usually only works together with one particular usbconn driver. + ==== Bus drivers ==== Bus drivers translate read and write operations on a bus into JTAG commands