Liking this, but all the mBed itself is a USB->Serial TTL cable, useful all the same.

You can Hack a Nokia DKU-5 cable (~£3) to do the same thing.

Next we need to turn the mBed into a JTAG itself.

Hi Andrew,

Yup, you are right mbed is now just a USB->Serial converter. I was hoping to make it control the reset and ISP lines, but as you saw, that turned out to be a bad idea.

The essence of this page is just to demonstrate the process, and give some confidence that there is a route to reuse the binary on a custom PCB.

I am working on the assumption that you'd prototype the hardware and software with the mbed module, and that when you come to program a custom PCB, you are in "production", so you dont need anything more than a mechanism to put the binary in the LPC. In this scenario JTAG doesnt give you anything more than ISP, other than a larger connector and a bunch more pullup resistors :-)

My assumption is also that if you needed to use all the extra features that JTAG gives, you'd be doing "product development" rather than "rapid prototyping" using a traditional Dev board, JTAG wiggler and offline compiler, rather than mbed.

They might not be valid assumptions, I'm happy to be told why :-)  - afterall this is still a bit experimental.

Cheers
Chris

So the intention that this is an experimental and educational tool?

If this is the case, could there be some merit in having a JTAG (even in a limited form) for educational purposes, for users using the mbed to learn Embedded Programming, using a JTAG can be a component of that education.

I have been struggling with this same general problem. I have several potential products  but the thing they all have in common is that the user is not an expert. They are seniors and kids so any update must be fairly simple. I think Flashmagic is too compllicated. The bootloader approach on Sparkfun tutorial is great because all it required is a file on a sd card. I tried to implement that on a program that I developed under Crossworks for Arm but it turned out to be too complicated for me to debug. I was hoping to just use mbed but it no one has yet done that bootloader I just mentioned. It would be great if someone did. We all seem to be inching towards it. I am impressed at how much has been done already by you mbed people.

This is a truely excellent guide and has got me really enthused about the awesomeness of the mbed. Many thanks for taking the time to write this up.

Hi Chris,

I was looking for information like that to go from the mbed to a custom board. This gives me more confidence now to go to the next step.

Thanks

PA

Nice writeup!

Unfortunately, I discovered that the BIN2HEX converter program does not run under 64 bit Windows.  I found another utility that does run under 64-bit, but it's limited to 64k binary files.  That utility can be found here: http://www.ht-lab.com/freeutils/bin2hex/bin2hex.html

Just stumbled upon this write up - good stuff!

Are there any plans to add a suitable ISP pin header to the Prototype2Product schematic (http://mbed.org/projects/cookbook/wiki/Prototype2Product)  (hint!) It would also serve as a useful hookup point for those debugging printfs...  For the lazy (ahem, time-poor) amongst us, a pinout compatible with the FTDI serial cables (http://apple.clickandbuild.com/cnb/shop/ftdichip?op=catalogue-products-null&prodCategoryID=105&title=USB-TTL+0.1%94+Socket) would be very cool.

On the same subject, the 10 pin mini JTAG/SW connector would be a welcome addition (or replacement) on the Prototype2Product schematic, for anyone wishing to re-create Jason's setup (http://mbed.org/users/tecnosys/notebook/lpc1768-programming-via-10pin-jtagsw/).  The 20-pin JTAG header takes up a lot of space on a board - too much when you're trying to minimise the cost of a PCB production run!

Hi Dan -

You and I think alike!

I'm in the process of laying out a PCB which has an FTDI compatable ISP header.  My goal is to make a cheap target board that can be used for simple "one off" projects.  I'm targeting a price point around $20-25 each.  To get there, I had to make some tradeoffs: the initial version does not have JTAG or the ethernet chip.  It does however, bring all of the Ethernet control pins out to a header.  So, its possible to add an external ethernet IC if needed.  (mini-jtag could be added, but the routing is already pretty crazy on a 2-layer board; it would probably make the board bigger.)

I can envision creating a few different versions; offering options like mini-JTAG, built-in ethernet support, and multiple USB ports - one for Serial via FTDI, and one connected to the USB pins of the 1768.

Unfortunately, I'm traveling for the next 6 weeks for work.  So in reality, a prototype PCB is at least a few months away.  (I have the components for several already stocked though.)

I'm open to feedback.

Cheers,

Rob.

Hi All,

I have just updated the LPC1768 reference design, so that the schematics include:

• 20 way 0.1" JTAG header
• 10 way 0.05" JTAG header
• 6 way header for connecting up an FTDI cable

Any other requests, just let me know!

Thanks,
Chris

For what it's worth, there is a standard ISP header (informal standard I guess) for the LPC chips here:  http://www.open-research.org.uk/ARMuC/Standard_ISP_Header.html

The 8-pin IDC cable header seems hard to find though, a 6-pin 2x3 IDC would be better IMO and can be gotten here: http://www.pololu.com/catalog/product/854

The FTDI cable option looks really good though...

I'm not sure I read over it somewhere or what I did read I didn't follow.  Can someone make up a bare metal schematic with BOM using the LPC1768 chip ?  The reference schematic to me doesn't make sense with this "IC2".  When I look at the pictures of the custom PCB above I see the microcontroller, a few resistors and a frequency chip.  But looking at the schematic I see the frequency chip connected to "IC2" but nothing connected to the LPC1768 ?

Any help would be greatly appreciated.

Thanks
-Frank

Hi Frank, the ref schematic is not the complete mbed schematic. The mbed interface chip (aka magic chip) is missing. In fact IC2 and LPC1768 are the same. The IF chip and the LPC1768 share the same 12 MHz clock on the mbed.

There are plenty of example schematics on the net of bare metal LPC1768 boards. For example the Keil MCB1700 is available [[http://www.keil.com/mcb1700/mcb1700-schematics.pdf | here]].

Regards

Wim

Hi,

Does anyone know of a bin2hex converter that can convert files bigger than 64k?

Much appreciated

Tim

-- Edit --

My mistake - bin2hex will convert bigger files if you add /2 after the binary file name. Now works great with my 410k file to a LPC1767.

I would like to use a process like this that uses the bootloader. However, this discussion seems a lot about how NOT to do things! It seems for us novices that a simpler and more practical tutorial would be appropriate.

My thoughts started along the line of mounting a ISP jumper on my custom PCB and then a push button to initiate programming. The jumper would be used temporarilly to set the ISP pin low while programming. The pushbutton would set the reset low and when released set it back high. This would initiate the bootload from the PC using FlashMagic.

Am I correct in assuming that that the bootloader wont work across the USB on the LPC1768? This would cetainly simplify the cabling.

We could just use a FTDI chip on the custom board to access the PC via USB since they dont tend to have serial ports.

But this is reallly ugly because we need pushbuttons, jumpers and a FTDI chip -- lots of precious board real estate.

We should think this through and find the best solution without using JTAG. We may end up with JTAG being the easiest solution in terms of real estate and board-mounted parts.   

Another question ...

Why can we get the exact functionality we have with the mbed with our custom board? We would add a USB connector that attaches to the PC. A button would perform the reset.

How would this be implemented?

I am able to communicate with my LPC1768 (I can see the synchronized message) and I was able to programme it using a FTDI cable and Flashmagic. The programming works without errors of any kind. But I am missing something : my small hello world programme :

#include "mbed.h"              

Serial pc(USBTX, USBRX); // tx, rx

int main() {
    while(1) {
        pc.printf("Hello World!\n");
    } 
}

thanks.

H.

Hermann Helmholz wrote:

I am able to communicate with my LPC1768 (I can see the synchronized message) and I was able to programme it using a FTDI cable and Flashmagic. The programming works without errors of any kind. But I am missing something : my small hello world programme :

 

#include "mbed.h"              

Serial pc(USBTX, USBRX); // tx, rx

int main() {
    while(1) {
        pc.printf("Hello World!\n");
    } 
}

does not work. I tried to reset the LPC1768 (put reset to ground) and still, I am unable to see the Hello World message. Am I missing a step? After programming?

 

thanks.

 

H.

Hi,

I think your program is working but you either need to use the USB serial library or use a different UART (e.g. p9,p10) and an FTDI chip to convert to USB or use TTL serial.

I suggest you recompile your code and add in a flashing LED so you can see the program execute.

Martin

Hi everyone,

I have try a simple LED programme. Here is the code :

#include "mbed.h"

DigitalOut myled(p9);

int main() {
while(1) {
myled = 1;
wait(0.2);
myled = 0;
wait(0.2);
}
}

Then, I did the following steps :

1- we compile a LED exemple using Mbed compiler.

2- we convert the binary file into hexadecimal file

3-we use Flash Magic to download the program into the lpc using FTDI cable.

4-once it s finished from programming we make a reset.

5- now we should see the led blinking but it does not work.

any idea?

thanks.

H.

Considering you program using ISP that should mean it is running its clock fine, so your code should work. I do assume you actually connected your LED to p9.

One option is that your binary to hex conversion goes wrong, although generally that happens with larger files only afaik. To be sure, I just converted that program to hex, you can see if that is the same file as you got: http://mbed.org/media/uploads/Sissors/test.hex

Thanks for your code. I just programme it on my chip. Then, I verify teh memory content and it is the same as the code. So, no dougt, the chip was programmed succesfully. However, the led does not blink.

any idea?

thanks,

H.

Now it works, I was connected on the wrong pin. That means that my problem is the bin2hex conversion. I was not able to install : http://www.hex2bin.com/bin2hex so I used this one : http://www.ht-lab.com/freeutils/bin2hex/bin2hex.html

as was proposed in the forum.

Are you using windows 7?

When compiling with bin2hex and commparing with your file, I see they are not the same. In my case, each line starts with :2 and in your case it starts with :1. Also, my lines are longer. However, one can see that both code is somehow the same. I was using bin2hex. What are you using?

thanks.

I am using objcopy, to be specific avr-objcopy. Here is another one: http://mbed.org/forum/electronics/topic/3291/?page=3#comment-17011.

Advantage of avr-objcopy is that you have it automatically available if you happen to have AVR studio installed (at least for version 4, but I expect also the other versions). Command is: avr-objcopy -I binary file.bin -O ihex file.hex

I do use it on vista, but I expect it then also to work on 7.

Hermann Helmholz wrote:

When compiling with bin2hex and commparing with your file, I see they are not the same. In my case, each line starts with :2 and in your case it starts with :1. Also, my lines are longer. However, one can see that both code is somehow the same. I was using bin2hex. What are you using?

thanks.

Ok, I made another board and it works fine. You are right, both HEX files works now.

The only difference between both boards is that I forgot to solder an inductor between the digital and analogical VDDS (the board that works does not have this inductor). I thought the inductor was meant to isolated both VDDS. I found the inductor in the schématic of lpcmini : https://mbed.org/users/chris/notebook/prototype-to-hardware/

thanks,

H.

Hi all,

I think I'm missing something?

Can't I program the chip directly from the computer's serial port? (flashmagic.exe or similar)

What are the advantages of using another chip? 

Thanks,

Quinton Wideman

Rolan Inc.

Does lpc1768 chip need oscillator to run? I saw 2 oscillators on that picture, which pin do they connect to ? and why 2 oscillators?

One looks like the 32.xxxkHz oscillator used for the RTC, if you dont want to use the RTC you shouldnt need it. Other one is main clock source. AFAIK you can also run from internal oscillator, but for many functions you will need a more accurate clock.

Erik Olieman wrote:

One looks like the 32.xxxkHz oscillator used for the RTC, if you dont want to use the RTC you shouldnt need it. Other one is main clock source. AFAIK you can also run from internal oscillator, but for many functions you will need a more accurate clock.

12MHz is the main clock for the LPC1768 (and the magic chip). Internally a PLL brings it to the 96MHz the mbed runs at. There is indeed also a 50MHz oscillator I didnt realise there was, indeed for ethernet. And finally a 32kHz crystal for the RTC (page 3 of mbed schematic, left bottom. It is a bit hidden).

Erik Olieman wrote:

12MHz is the main clock for the LPC1768 (and the magic chip). Internally a PLL brings it to the 96MHz the mbed runs at. There is indeed also a 50MHz oscillator I didnt realise there was, indeed for ethernet. And finally a 32kHz crystal for the RTC (page 3 of mbed schematic, left bottom. It is a bit hidden).

Thanks for your help again, me and my team is doing senior design for college.

Thanks all for the posts.  I'm working with the FRDM-KL25Z board, and was thinking that the "open SDA" components  - the second USB port, K20 "magic chip" and other stuff from page 4 of the schematic would be usefull as a programming dongle, no?  The inteface signal list between dongle and target is short at 5 and there's no reason to devote space to this stuff on a production target.

edit - should have read the manual because it looks like they have thought of this already.  Section 5.2. of FRDM-KL25Z User's Manual shows how to use the FRDM board to program off-board MCUs.

Hey Chris,

I followed exactly what was mentioned in the HDK guide. I created my board and this is what I found:

1) The very first time when I connect the board, I press the switch 1 and I am able to dumb the lpc11u35_lpc1768_if_mbed.bin file into the 11U35.

2) I, then, power toggle it by removing and reattaching the USB cable. Now I can see the mBed drive in my device manager. I keep the switch 2 pressed, open this drive and load my compiled code in it. I keep the switch pressed until then.

3) Now I release the switch, the code starts running but the mBed drive and the COM port vanish from my device manager.

Is there something that I am doing wrong?

Please suggest.

Neel.

I WANT TO KNOW CANT WE USE THE KEIL TO GET THE HEX FILE FOR THE SAME PROJECT BY EXPLORING THE PROJECT AND USE AS OFFLINE

Hi,

I was able to read the device signature but got the message "Unable to communicate (transmit/receive) when tried to download the HEX file to the target board (LPCExpresso) by Flash Magic. Please suggest!

Thanks,

Tony

I would like to build a custom board with the FRDM-K64F (MK64FN1M0VLL12) with only a single MCU chip. Has anyone tried this and what pitfalls would I need to avoid in the hardware design?

In terms of software, the following library makes downloading a new program possible: Bootloader_K64F

The first program with the bootloader code would need to be downloaded with JTAG or a second FRDM-K64F board. The K64F USB port does not support serial natively without mbed libraries (USBserial). This means the bootloader code needs to copy the program to intermediate Flash memory sectors as received over USB serial, and then write the program to the Flash memory boot sectors.

I'm documenting my progress: FOTA for FRDM