bootstrap mode for Motorola Coldfire MCF5206?

----- Original Message ----- From: "Herbert Wagner" Newsgroups: comp.arch.embedded Sent: Tuesday, January 17, 2006 10:40 AM Subject: bootstrap mode for Motorola Coldfire MCF5206?

You'll have to write your own bootloader and put it in ROM. You need to implement a filing system to get the boot code off a flash memory card and copy it to RAM, then execute the code in RAM. To cope with the first time when you start with a blank card without any boot code it needs to be able to accept an initial upload from the serial port.

New versions of software can be uploaded by serial port. Just write some code that accepts whatever format your linker puts out. Copy this to RAM and when the transfer is complete then write the boot code to flash. Peter

Thanks, Peter. I'm aware, that I have to copy the operating system's code from Flash to RAM. However, I want to avoid adding an extra boot ROM. (Besides, is it possible to program Flash RAM before soldering it into the circuit board? Or are the data likely to be destroyed during soldering?) If the Coldfire doesn't support a mode to reprogram Flash, are there any devices, that allow this procedure? I imagine to change some jumpers, program Flash via a serial interface (USB,RS232,I2C), set jumpers back to normal operation. Sorry, if this question is stupid. I have only experience with PIC microcontrollers, where this is possible.

Jens

Jens, with bigger CPUs your only bet is JTAG - I believe the Coldfire has it. With CPU32, they also have the BDM interface, which also can be used. I have always used JTAG (even on CPU32), because it also takes care of debugging the board, programming the CPLDs etc. In order to just solder the flash memory to the board and program it for the first time, you drive the address and data lines via JTAG so the flash gets programmed. Takes longer because of the serial nature of JTAG, but you really need to write some loader which could subsequently program the whole flash via a faster interface. Anyway, apparently you ask only about that first ever programming, you know what to do afterwards. I am not aware of the PC based tools as I use my own, DPS based hard/software, so perhaps someone else could suggest what you need to be able to do that.

Dimiter

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I think, this answers my question. Didn't know that JTAG is the solution. I will need to get familiar with this interface. Thank you!

Jens

Some Coldfires have JTAG interfaces, but (on the Coldfires I have used) this is only for boundary scan. The BDM port is for debugging and can easily be used for programming. There are lots of tools on the market, ranging from free (cheap or home-made bdm dongle, combined with open-source software) to very capable but expensive tools (such as Abatron). You probably want to have a look at

I meant exactly using the boundary scan to program the flash, this is how I am doing it with my tools. BDM or secret JTAG registers based tools may work, but are a lot less universal and get you stuck with the suplier as you don't know what they are doing (I am not sure about BDM, actually, it used to be documented up to a point for CPU32, but it is a unique interface anyway whereas JTAG is pretty widespread). I did not know the Coldfire had BDM, years ago, when I was looking where to move to from CPU32, I opted for the PPC and have not looked at the Coldfire since.

Dimiter

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The Coldfire BDM, like the CPU32 BDM, is pretty well documented. It is a noticeable improvement over the CPU32 BDM (less pin multiplexing, and some more internal hardware). Like "secret JTAG register tools", using the BDM rather than generic boundary scan flash programming is going to be very much more efficient (whether that is relevant or not depends on your flash programming speed, and the size of the download), more flexible for some uses (for example, you can download a memory test routine to internal ram and run that much faster than a boundary scan based memory test), and probably vastly cheaper and easier to set up. If you already use boundary scan extensively, and have the required software, then it's a different matter, obviously. I'd be very surprised if boundary scan techniques were the best solution for flash programming for most users - although I don't know much about its use in practice other than what some sales reps told me.

You can download the memory test using the right JTAG tools as well.

It will take some figures to make me believe that... :-)

flash

I'd be less than surprised if they were, actually - provided the tools those sales reps told you about were capable of doing it (many are not). They typically use the secret JTAG registers which - surprise - are documented only for tool vendors owned by or closely related to the manufacturer. Why are they doing it is another matter (the profits JTAG toolvendors make are negligible for big silicon manufacturers). Using general JTAG capabilities only has its advantages . I must admit, though, that with the growing complexity and all those mergers/acquisitions staying independent becomes more difficult every day...

Dimiter

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Free. (as in Beer and Speech).

Compiles for linux and windows.

On a recent project I used the library to write a custom flash programmer / production tester.

Regards

Paul

Another poster gave you the prices for a Cybertec BDM unit (I've got one

- it works well) along with the open source BDM software. That's a very flexible solution, although it might take some time to get set up as you want it if you are not used to that sort of software. For a ready-to-run and easy-to-use solution, you can look at P&E Micro, which includes software, but costs a little more.

The JTAG boundary scan hardware and software we heard about was very much more expensive - a completely different price class. I'm sure that when used appropriately, such tools can be very worthwhile, but they are for a different job.

Many micros have a JTAG with "secret" registers (which may or may not be documented) for debugging and programming - I'd classify these along with Freescale's BDM interface. You typically buy/build a dedicated dongle, consisting of a parallel port connector and a couple of logic chips and resistors, and use cheap or free software for programming.

But using general purpose boundary scan for programming flash when you have a micro on board ready to do the work, seems a poor solution to me, akin to using an embedded PC for an embedded system when a small

flash