Hello,
I want to design a usb link with OpenSDA. Very simple similar to this
The FRDM boards use K20 mcu and the LPC Link 2 use LPC4370.
Can I use other more simple and cheap Kinetis mcu with OpenSDA for that?
Best regards
Hi!
I'd like to share a similar concept for JTAG debugging with the NXP Power Architecture with you. We used to use the low budget evaluation board TRK-USB-MPC5643L as early development platform. During development, we had bricked several of the devices (seemingly due to bad debugger behavior with unprotected devices). A look into the schematics revealed that not only the pins of the JTAG connector on that board are connected to the MCU pins (for the intended purpose of debugging with an external JTAG debugger) but also the same, according set of signals from the on-board OpenSDA chip (intended for debugging over USB without additional hardware).
So why not using the JTAG connector as an output - to control another board? Only further condition: All affected pins of the MCU on the evaluation board need to be passive. Easy in our situation, we just unsoldered the bricked MCU from the boards. The wiring is a 14-wire one-by-one ribbon cable with two identical JTAG connectors at either end.
No software or configuration change is required. The debugger configuration settings in both, Code Warrior and S32 Design Studio, recognize the USB wire to the OpenSDA chip on the stripped evaluation board like they do with a P&E Multilink debugger and the same standard project settings can be used.
The solution has been tested with different boards (MPC5643L, MPC5748G and MPC5775B) and both mentioned development environments. The only perceivable difference to a true P&E Multilink is the a bit lower data transmission speed during flashing.
Not sure if you have seen the tinyK20 we did at the Lucerne University:
tinyK20 Open Source ARM Debug/Universal Board – First Prototypes | MCU on Eclipse
tinyK20: New Board with micro-SD Card | MCU on Eclipse
Production tinyK20 Boards arrived! | MCU on Eclipse
It is basically using the OpenSDA circuit from the FRDM boards, but can be used as standalone breakout board (main purpose) or as a board to debug other Kinetis devices using CMSIS-DAP. It is using the same K20DX128 as on the FRDM boards: that way it is binary compatible to it.
We looked at using a differnt MCU, but this was not really feasible:
- price was rather high because of small number of boards. Our batches were in the 100-200 range to equip students with breakout boards.
- using a different microcontroller would require to port the bootloader. But because the OpenSDA 2.0+ bootloader needs using proprietary and expensive tools (see Adding a Delay to the ARM DAPLink Bootloader | MCU on Eclipse ) plus would need extra efforts we did not consider that option.
With that small number of boards, the BOM of the K20 including assembly (without any cables) was around $20.
So for us using the K20 was a good choice and has worked out very well. Later versions of a similar board have the K20 embedded on the board too: First tinyK22 Board with NXP K22FN512 ARM Cortex-M4F | MCU on Eclipse
If anywone would be interested to invest money and produce a large batch of boards to get the costs down, this could be considered of course. Ping me directly and I can see if there is any interest :-).
I hope this helps,
Erich
Hi Dylan,
yes, this is exactly what the tinyK20 is able to do.
On the tinyK22 the OpenSDA circuit is embedded on the board as it is for example on the FRDM-K22F board.
In case you are not aware: you can use an existing board (e.g. see Using the Freescale Freedom (FRDM-KL43Z) to Debug other Boards | MCU on Eclipse) to debug another one. It depends a bit on the board, but in most cases you need to add a jumper/cut a trace and add a header.
An even better and less expensive way is using the LPC845-BRK for this:
Tutorial: Transforming the NXP LPC845-BRK into a CMSIS-DAP Debug Probe | MCU on Eclipse
For $5 you have a development board and a debug probe:
or see Using the LPCXpresso V2/V3 Boards to Debug an external Board | MCU on Eclipse .
Just one word on this: all these options are low cost options, so don't expect ultra fast debugging or flash programming. A Segger J-Link, LPC-Link2 or P&E Multilink are much more convenient to use and fasters by factors.
You can get a J-LINK EDU for $20, or a LPC-Link2 (if you are not aware of it) for $20 too (see Custom 3D Printed Enclosure for NXP LPC-Link2 Debug Probes | MCU on Eclipse ). I really recommend to invest at least that money.
I hope this helps,
Erich
