Using custom BSL/SBW

Mike Kaelin said:

I’m working on a small board, and because of various constraints, it will be sealed and the only access to programming the MSP430 program flash will be through a USB, using a USB/UART converter chip. I’ve read through the appnote SLAU319 but I’m still not sure about the entire procedure. The target micro is a ‘G2533 or similar.

You can use (open source) BSL (on PC side) prepared by TI with higher rate than 9600 bps. TEST / RESET lines must be used for BSL entry sequence. Bit-banging SBW over UART is not possible because of UART low speed. There are also some other non-BSL, boot loader (using UART) solutions, for example...

http://forum.43oh.com/topic/3661-1k-serial-gdb-bootloader

Hi Luis,

Thanks for a great answer. You've confirmed a lot of what I thought I understood from reading the appnotes.

Like I said, my customer wants this completely sealed, and the whole board will be about a half-inch square, so the normal MSP430UIF is not an option. I basically need laptop USB directly to 'G2xxx programming. It's no problem to put in the TST/RST control lines for BSL entry, but it seems to me like that customizes it enough that a "standard" USB download program wouldn't work.That's really the crux of my confusion - how do I get from a standard download program to the TST/RST/RX/TX pins that are defined in the appnote? Is there a GUI version of BSLDEMO (i.e. not a command line) or some other windows-based downloader?

I'm  not anxious to write my own download utility.There are several USB/UART converter chips available, and I assume that the setup to control the programmable I/O is not a standard, so a generic PC program would have to either handle multiple USB chips, or be specific to one or the other. Or maybe I run a short program that does the TST/RST sequence with my chosen USB/UART chip, then call BSLDEMO? I could do that for the factory programming, and thereafter send a command via UART to start the BSL.

It's an option for me to get the Saleae Logic, but I've already got a couple of analyzers... just in case I do have to write my own downloader, any chance you could send me a couple of screen shots of the sequence - if it's long, you can skip the downloaded program, I just want to see the sequence leading up to it and maybe the finish.

Thanks, Mike.

Hi Zrno,

Thanks! The link you provided is interesting, but my customer wants this sealed up and programmed only through the USB (including first download). Like I said in my reply to Luis, the missing link is getting from a standard (?) downloader program to the TEST/RST/RX/TX pins. There will be a USB/UART adapter (with possibly some programmable I/O pins) between PC and micro, but nothing else.

If I connect a (generic) USB/UART chip so that DTR goes to reset and RTS goes to the TEST line, will download work with any software that downloads via the MSP430UIF? And if so, (not that I really need it) would debugging also work through this interface? Does TI have a GUI based downloader (i.e. not a DOS command line!)

Thanks, Mike.

I made my own software/hardware BSL, SBW and bootloader, so it is possible if you have some special reason for this, and large amount of free time. In this case there is also USB bit-banging possibility that enable direct connection of MSP430G2xx to USB with same simple glue logic.

http://forum.43oh.com/topic/2962-bit-bang-usb-on-msp430g2452

In any other case you need one extra IC on board.

If you want BSL, than extra IC will be USB-UART bridge chip that also have possibility to control TEST/RESET lines (and AFAIK all of them have it). You don't need 2 USB-UART bridges, because it can be used for BSL and normal (not programming) communication with PC, but TX/RX pins will be fixed to timer pins (because of BSL) on MSP430, so software UART must be used, not hardware. If you have some communication where is known who is sending to who, what size, and when, no problem at all.

http://forum.43oh.com/topic/1284-software-async-serial-txrx-without-timer

If you want SBW (with USB-UART bridge possibility) than extra IC will be MSP430F5xx. You can use original open source MSP430F5529 LP project and shrink it down to 32 KB, so it can fit on low-cost, small size, MSP430F5510.

http://processors.wiki.ti.com/index.php/MSPDS_Open_Source_Package

Hi Zrno,

Consider this a "least time and effort" design. I don't want to develop any PC software if I don't have to.

This is what I'm planning: a standard USB/UART bridge (for example CP2102, FT234XD, FT230X - these all have USB to 3.3V UART plus a couple of programmable pins) connected to an MSP430G2533. The bridge UART pins are connected to the MSP430 UART pins, with glue logic like inverters if necessary. DTR from the ridge is connected to RESET and RTS is connected to TEST. This is pretty similar to what is described in the appnote SLAU319H chapter 4.

So, I have more or less replicated the appnote hardware. Without doing anything to the DTR/RTS pins, I will have USB/UART communications to the MSP430.

Now, my question is, will some currently available PC software download an MSP430 text file to program the part? Is it going to be dependent on the bridge chip, or will it just control the DTR/RTS pins to invoke the BSL, and the bridge driver will handle it from there?

Which programs will work? One of the programs included in one of the appnotes? Will the IAR debugger program it directly? Not necessary, but would it also debug with this interface? There used to be a little windows-based program called MSPFET that would download txt files using the MSP430 USB FET tool, will that work?

Thanks, Mike.

BTW, is there an error in appnote SLAU319? I'm looking at version H that I downloaded a a couple of days ago, and for the G2xx3 it shows the TX connected to P1.1 (per datasheet UCA0RXD) and RX connected to P1.5 (UCA0STE). Shouldn't that be P1.2 (UCA0RXD)?

Thanks, Mike.

sorry, mistyped and can't edit posts - P1.2 is UCA0TXD.

Mike Kaelin said:

Now, my question is, will some currently available PC software download an MSP430 text file to program the part? Is it going to be dependent on the bridge chip, or will it just control the DTR/RTS pins to invoke the BSL, and the bridge driver will handle it from there?

Which programs will work? One of the programs included in one of the appnotes? Will the IAR debugger program it directly? Not necessary, but would it also debug with this interface? There used to be a little windows-based program called MSPFET that would download txt files using the MSP430 USB FET tool, will that work?

For example...

http://www.flyingcampdesign.com/msp430-bsl-programmer.html

For programing can be used TI open source BSL tool (slau319 MSP430 Programming Via the BSL), and bridge will work like USB-UART bridge, virtual serial port (CDC), without any special driver (except one for bridge chip).

BSL is used only for flashing, not for debugging (SBW / JTAG), and AFAIK it is not supported by software used with FET debuggers.

Repeat, only "problem" is that you are forced to software UART on MSP430, because of BSL (RX/TX lines). You can't use MSP430 hardware UART because hardware RX/TX pins are different that one used by BSL.

Yes! The FlyingCampDesign docs demonstrate exactly what I want... I'm OK not using this circuit for debugging, I was just curious about that. I'll order a couple to play with.

I'm not sure I understand your last statement though - is there a reason why the UART can't be used for both normal communications and the BSL? Either I'm using the MSP430 UART to talk to the USB port, or the USB takes control of the MSP430 for the BSL function. They don't have to work at the same time.

Is it possible that I need to disable the RTS/DTR pins if I want to just have a standard USB UART?

Hi Mike,

As you noticed, G2xx3 uses P1.1 and P1.5 for BSL which don't correspond to the USCI pins, and not only that, but P1.1 has a different functionality (TX instead of RX). The reason for this is that BSL is implemented as a Timer-based UART. 

As zrno mentions, you would have to use a "Software" UART instead of using USCI, or you would need a hardware solution.

So, for HW:

* Your interface can be USB, but you should consider the following:

   -  your USB-UART bridge needs to have control of DTR/RTS to force the entry sequence.

   - The Rocket-BSL (mentioned in previous thread) does that by implementing a USB-UART bridge with a MSP430F55xx.

   - As mentioned, the FCD-PRG01 does something similar with a FT232R.

   - You'll only have access to BSL, not SBW/JTAG, so you can only program the device, not debug it.

   -  As mentioned above, the pins used for BSL are not the same as USCI.

* If you don't add the USB connector but you make available TXD, RXD, RST and TEST to use BSL:

 - You'll probably need to make a custom adapter if you want a small connector

  - You can use your own external USB-UART bridge, or you could use something like the Rocket-BSL, or Elprotronic's FlashPro430 (http://www.elprotronic.com/flashpro430.html) 

* With RST and TEST you can use SBW:

 - You'll probably need to make a custom adapter if you want a small connector

  - You can use something like the MSP-FET430UIF 

 - You can download and debug

And for SW:

* If you use BSL:

  - BSLDEMO in SLAU319 is available as .exe and also as source 

  - Flying Camp has an open source GUI

 - Python tools (https://pypi.python.org/pypi/python-msp430-tools)

* SBW:

 - IDEs such as IAR, CCS

  - MSP430 Flasher (http://processors.wiki.ti.com/index.php/MSP430_Flasher_-_Command_Line_Programmer)

  - FET-Pro430 (http://www.elprotronic.com/download.html)

Regards,

Luis R

Hi Luis,

I will be using the BSL similar design to the FlyingCamp board, either with a FT232 or a CP2102 (which the customer has in his stock already).

Is it just the G25x3 that is bit-banging the BSL UART, or all the G series? Is the F2xxx family using the UART peripherals or do they bit bang too? If all of the parts are bitbanging the BSL, is there a reason why I couldn't put the BSL pins in parallel with the UART peripheral pins?

Again, many thanks for clearing this up!

Mike.

Thanks to both of you - Great Job!

Mike,

You got good responses and seems all set to go. However, the following points might still help.

1) Most USB to serial chips provide 3.3V I/O, but most ready made USB to serial cables convert those 3.3V I/O to +/- 12V RS232 levels which is not compatible with G2553. So you need to by-pass that or convert them back to 3.3V.

2) The "modem control signals" DTR and RTS, if in 3.3V, can be used as nRST and TEST for G2553. The PC program can control those signals to do the BSL entrance sequence.

3) The PC program BSLDEMO2 does almost exactly the above. But it might have inverted DTR. You can download the source code, change the DTR usage, and recompile it.

4) Elprotronic (even the Free version) can use BSL too. It use Windows GUI. Check it out!

Mike Kaelin said:

I will be using the BSL similar design to the FlyingCamp board, either with a FT232 or a CP2102 (which the customer has in his stock already).

You can search on net, for device that have most stable drivers (working on all OS's), highest BR, and low price. Maybe there is better device than costumer have in stock already.

Your MSP430x2xx device will use forever bridge chip for communication with PC, so there is no more 115200 bps limitation, it can go over this...

http://forum.43oh.com/topic/3413-msp430-uart-benchmark/?p=34429

Mike Kaelin said:

Is it just the G25x3 that is bit-banging the BSL UART, or all the G series? Is the F2xxx family using the UART peripherals or do they bit bang too? If all of the parts are bitbanging the BSL, is there a reason why I couldn't put the BSL pins in parallel with the UART peripheral pins?

You can use software UART, but if you can find some extra space on board there is elegant solution, that enables BSL and hardware UART, and cost less than nothing.

Here you can see BSL / SBW / JTAG entry sequence (case 3 where at the end BSL is enabled) from slau320...

During normal program running (when bridge is used for non-BSL communication) TEST pin on MSP430 will be low. During BSL running (flashing), TEST pin will be high. You can use sn74lvc2g125 and sn74lvc2g126 with TEST signal for enabling / disabling gates. When TEST is low, sn74lvc2g125 will enable hardware UART lines and sn74lvc2g126 will disable BSL UART lines, and opposite.