Custom TMS57012 Launchpad Circuit

Edwin,

No problem with you modifying the launchpad - in fact this is why we post the eagle files.

You really only need to program the TM4C unless you want to also flash our demos.

To program the TM4C we use this batch file:

STEP1: PROGRAM FIRMWARE LAUNCHXL2-TMS57012

@echo off
setlocal

REM
CALL ..\common\setccsvars.bat
set sn=HL512000

echo Short and Hold U7-59 to GND
PAUSE
@echo on
%xdspath%\xdsdfu -b %bootloader% -r
PAUSE
%xdspath%\xdsdfu -f %firmware% -s %sn% -r
PAUSE
%xdspath%\xdsdfu -e
PAUSE
endlocal

and the 'setccsvars.bat' file is just:

set ccspath=c:\ti\ccsv6\
set xdspath=%ccspath%\ccs_base\common\uscif\xds110
set scriptpath=%ccspath%\ccs_base\scripting\examples\loadti
set bootloader=%xdspath%\boot_loader.bin
set firmware=%xdspath%\firmware.bin

which you need to adjust for your computer.

We have an issue with flashing the TM4C initially on the TMS57012 board.  Initially you have to have a pulldown or temporarily short the RBIAS pin to ground - it is floating on LAUNCHXL2-TMS57012 and if you leave it floating you can't program the bootloader.   (The firmware you can program, long story).

So add a 4.87K (or 4.7K) resistor from RBIAS to GND on your redesign, and then you can skip the
"echo Short and Hold U7-59 to GND"

Yes, the boot ROM in the TM4C will enumerate it as a USB Device Firmware Upgrade device and the xdsdfu utility will then be able to flash it over USB.

You need the RBIAS resistor, unless you want to hold a probe on pin U59 while you program the bootloader (not recommended unless you do it under a microscope!) Also you shouldn't change the version strappings, the crystal or anything else really on the TM4C. Don't even change the package.

Not sure what the scope of your project is, but you could also put the TM4C on it's own board and use it as a JTAG tool like a standalone XDS100v2 - instead of putting it on the same board as the Hercules part. This way in your application - you only have to power the Hercules part. We put them on one board on the launchpads for simplicity in the 'out of the box' experience - less to connect means less steps till you are up and running. But most people wouldn't put the TM4C on their own design... just the part that is being used. Up to you of course it would work either way.

Ok, I missed that.

The JTAG signals (TRST, TCK, RTCK, TDI, TDO, TMS) are definitely required.

The MR_PB signal allows the TM4C to issue a Power-On-Reset to the Hercules which is nice to have because you can control this from CCS. It's not required though.

The ICORE isn't something you should need - eventually we hope to add power consumption measurement to the launchpad and that's what this signal is for. Means you could also drop the INA210_DCK and the 10mohm current measurement resistor.

The two LIN pins allow you to use a UART on the hercules with a Terminal program on the PC like PUTTY to display information. You get the convenience of using the same USB cable for the terminal and the debug probe -- instead of having a separate DB9 serial header or other USB-Serial solution. Up to you if you want that.

External Debug I didn't see in your schematic, but it's there to turn the on-board TM4C debug probe 'off' if you plug an external debug probe into the 20 pin JTAG header. If you're basically turning the TM4C into an external probe - you can drop this signal but you should make sure the TM4C pin is pulled up to +3.3V.

Powering the 2 boards is tricky. I'd probably suggest using a barrel jack to power your hercules board, and for the TM4C you could power through USB like we show in our schematic. If you want to be safe you should put something between the two boards to make sure the IOs of one don't drive the other in case say the USB cable is plugged in, but the barrel jack isn't. The CPLD on the XDS110v2 design performs this function - so you could reuse that CPLD if you wish.

If you are going to power Hercules from something other than USB and you can provide > 6VDC you might want to look at the control cards and the TPS65381 which is the safety companion chip. If you're really into safety for your project this might be the way to go because the safety library has support for the TPS65381.
However it does make working with the part trickier because it brings in an external watchdog among other checks.

It's many pins, you'll have to look at the schematic. U7B sheet 13.
It takes 3.3V but regulates this down to 1.2V internally. You do need to provide capacitors on the 1.2V pins though.