Flash Breakpoints

The J-Link software contains an additional feature, called flash breakpoints (FlashBP). Flash breakpoints allow the user to set an unlimited number of software breakpoints when debugging in flash memory, rather than just the 2 hardware breakpoints. Setting the breakpoints in flash is executed very fast using a RAM code specifically designed for this purpose; on chips with fast flash, the difference between breakpoints in RAM and flash is unnoticeable. This feature requires an additional license from SEGGER.

List of supported microcontrollers

How do breakpoints work?

There are basically 2 types of breakpoints in a computer system: Hard ones and soft ones. Hardware breakpoints require a dedicate hardware unit for every breakpoint. In other words, the hardware dictates how many hardware breakpoints can be set simultaneously. ARM7 and ARM 9 cores have 2 breakpoint units (called "watchpoint units" in ARM's documentation), allowing 2 hardware breakpoints to be set. Hardware breakpoints do not require modification of the program code. Software breakpoints are different: The debugger modifies the program and replaces the breakpointed instruction with a special value. Additional software breakpoints do not require addi- tional hardware units in the processor, since simply more instructions are replaced. This is a standard procedure that most debuggers are capable of, however, it requires the program to be located in RAM.

What is special about software breakpoints in flash?

FlashBP allows you to set an unlimited number of breakpoints even if your application program is not located in RAM, but in flash memory. This is a scenario which was very rare before ARM-microcontrollers hit the market. This new technology makes very powerful, yet inexpensive ARM microcontrollers available for systems, which required external RAM before. The downside of this new technology is that it is not possible to debug larger programs on these micros in RAM, since the RAM is not big enough to hold program and data (typically, these chips contain about 4 times as much flash as RAM), and therefore with standard debuggers, only 2 breakpoints can be set. The 2 breakpoint limit makes debugging very tough; a lot of times the debugger requires 2 breakpoints to simply step over a line of code. With software breakpoints in flash, this limitation is gone.

How does this work?

Basically very simple:
The J-Link software reprograms a sector of the flash to set or clear a breakpoint.

What performance can I expect ?

A RAMCode, specially designed for this purpose, sets and clears flash breakpoints extremely fast; on micros with fast flash the difference between breakpoints in RAM and flash is hardly noticeable.

How is this performance achieved ?

We have put a lot of effort in making flash breakpoints really usable and convenient. Flash sectors are programmed only when necessary; this is usually the moment execution of the target program is started. A lot of times, more then one breakpoint is located in the same flash sector, which allows programming multiple breakpoints by programming just a single sector. The contents of program memory are cached, avoiding time consuming reading of the flash sectors. A smart combination of software and hardware breakpoints allows us to use hardware breakpoints a lot of times, especially when the debugger is source level-stepping, avoiding reprogramming flash in these situations. A built-in instruction set simulator further reduces the number of flash operations which need to be performed. This minimizes delays for the user, maximizing the life time of the flash. All resources of the ARM micro are available to the application program, no memory is lost for debugging. All of the optimizations described above can be disabled.

Using FlashBP

Licensing

The software is licensed on a per J-Link basis. It requires a J-Link with FlashBP feature. If you want to use FlashBP with J-Link GDB Server or J-Link RDI you will need an additional license for these software components.

In order to receive your free 30 days trial license, please send an e-mail including the J-Link serial number to このメールアドレスはスパムボットから保護されています。閲覧するにはJavaScriptを有効にする必要があります。 .

Using FlashBP with different software components

The FlashBP feature can be used with the following J-Link software components:

• J-Link ARM DLL. (For example if you use the J-Link ARM DLL natively in IAR Embedded Workbench for ARM or RealView^® MDK)
• J-Link GDB Server
• J-Link RDI

For more information about how to use FlashBP with the different software components, please refer to the corresponding manuals.

J-Link Renesas RX support

J-Link is compatible to the Renesas RX600 series MCUs. All that is needed to use J-Link with a Renesas RX600 series MCU, is an RX Adapter which is available for J-Link, J-Link Pro, J-Link Ultra, J-Link EDU and any other licensed J-Link compatible emulator. The required software can be downloaded from SEGGER's website and used free of charge.

Features

• Supports direct download into flash memory
• Supports software breakpoints in flash memory (Flash breakpoints)
• Seamless integration into the Renesas HEW & IAR Embedded Workbench IDE
• On-chip trace support
• Virtual UART support (C2E support)
• All kinds of events are supported (Execution break, data access, trace break, combintation/sequentation of events)
• 20-pin to standard 14-pin Renesas JTAG connector
• USB 2.0 interface
• JTAG speed up to 12 MHz / 25 MHz (depending on J-Link model)
• No power supply required, powered through USB
• All JTAG signals can be monitored, target voltage can be measured
• Support for multiple devices
• Fully plug and play compatible
• Wide target voltage range: 1.2V - 3.3V, 5V tolerant
• TCP/IP server included, which allows using J-Link via TCP/IP networks
• Target power supply: J-Link can supply up to 300 mA to target with overload protection

• Available RX hardware
• Compatible MCUs
• J-Link vs. Renesas E1. What are the advantages of J-Link?
• Getting started
• Flash prgramming via J-Link Commander

Available J-Link RX hardware

RX adapter


All that is needed to use J-Link with a Renesas RX600 series MCU, is a regular J-Link + the 20-pin to 14-pin RX adapter.

Compatible MCUs

J-Link RX support supports all RX-CPUs with RX600 core and JTAG interface. The following devices / device groups are known to be compatible:

• RX610 Group
• RX62N Group, RX621 Group

J-Link vs. Renesas E1. What are the advantages of J-Link ?

Getting started

J-Link RX is compatible to the regular J-Link and uses the same USB driver. In order to install the driver, simply download and install the latest software and documentation pack of J-Link:

J-Link software and documentation pack download page

In order to verify the correct installation of the J-Link USB driver, simply start J-Link commander, a small command line-based tool which comes with the J-Link software.
J-Link commander can be found at Start -> All programs -> SEGGER -> J-Link software version -> J-Link commander. If the installation of the driver was successful and J-Link + target board are connected to the PC, the output of J-Link commander should look like this:

Setup J-Link RX for use in Renesas HEW and IAR EWRX

J-Link RX is fully compatible to Renesas E1 emulator and works with Renesas HEW and IAR Embedded Workbench for RX (EWRX).
The J-Link RX software is a package of DLLs which replace the original Renesas DLLs used for E1/E20 and can be downloaded here:

J-Link RX software download (V4.24c)

Subscribe to J-Link RX software notification

For more detailed information how to setup J-Link RX for use with HEW and EWRX, please follow the instructions in the Readme.txt which comes with the software package.

Beta software

Currently there is no new beta version. Please use the current release.

Using J-Link RX with Renesas HEW and IAR EWRX

Since J-Link RX is fully compatible to the Renesas E1 emulator, all features supported by the IDE + E1 can also be used with J-Link RX. J-Link RX has been tested with the following IDEs:

• Renesas HEW
• IAR EWRX

Flash programming via J-Link Commander

The built-in Flash loader can be used to program the flash of supported RX devices directly from within the debugger or via J-Link commander. This allows using J-Link for flash programming of smaller production batches. To program the flash via J-Link Commander, a sequence of commands such as the following can be used:

speed 12000                       // Select High JTAG speed
h                                 // Halt target CPU
exec device=RX600                 // Select correct device (RX600, RX62N, RX62T) to enable flash programming
loadbin C:\file.bin,0xFFF80000    // Load program into flash
r                                 // Reset target CPU (not required if all you want to do is program flash)
g                                 // Start target CPU (not required if all you want to do is program flash)
q                                 // Quit

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