MSP430F6736A: BSL Communication Issue on MSP430F6736A Using MSP-FET

I check the hardware connection on MSP-FET and MSP430. They are all right. Not quite sure why the BSL ack failure happens.

Can you use a logic analysier to see what happens on Test, RST, RX and TX?

Hi Eason,

Please find the TEST, RST , TX and RX pin state while running the BSL script

In addition to the previous query, we have observed an issue with the voltage levels being applied by the MSP-FET debugger. Our system supports 3.3V, but during debugging, we noticed that 1.8V is being applied through the VCC pin.

Could you please guide us on how to configure the MSP-FET debugger to support a 3.3V supply to match our system's requirements?

The signal voltage level is quite strange. For example the TX voltage change(1V) is much different with RX voltage change(2V).

The MSP-FET with default can output 3.3V. Can you directly test the MSP-FET without any connection? I suppose your PCB drive too much current.

You can try to use VCC-TARGET instead of VCC-TOOL (Use external power supply to provde the power for MSP-FET)

Hi Team,

We attempted to use the FTDI FT4232 chip instead of the MSP-FET debugger to interface with the MSP430 through BSL UART. We connected DBUSUSB0/1 for TX/RX, along with TEST and RST pins. However, we're still facing the same acknowledgment (ACK) issue when running the BSL script.

Here’s what we’ve tried:

Software Invocation:
We disabled interrupts and used a software call to jump to the BSL:

__disable_interrupt(); // disable interrupts

((void (*)())0x1000)(); // jump to BSL

We attempted to observe the TEST and RST sequence mentioned in the documentation while invoking BSL through Application ("BSL starts with two rising edges on TEST, and TEST held high when RST rises"). However, on the oscilloscope, this sequence was not detected.

Could you advise on whether our invocation method is correct? Are there specific considerations when using the FTDI FT4232 chip for BSL UART?

Gentle reminder on the query 

Sorry, I just return from a long holiday.

1. Why you want to change another tool? I have no idea about the FTDI FT4232. I don't think the problem lies on the tool.

2. When you use MSP-FET, I think you observe the invoke sequence on reset and test pin. Besides, you still don't answer my question about the voltage level.

3. The first thing is to make sure whether the device enter BSL mode. I would suggest you to download a GPIO toggle code into the MCU. If it enter the BSL, you should see the GPIO toggle will stop.

4. The second thing is to make sure the communication setup is good. It seems that you trapped at this step.  So you need to use a  logic analysier to interrrupt the communication to know what happens.

Hi Eason,

As per your suggestion, We have programmed the MCU with a GPIO toggle code, and the GPIO toggling function stopped once we ran the BSL script. However, we still facing same Unknown ACK failure 
To clarify the power configuration, we’ve supplied 3.3V externally to the target . We intended to use FTDI as a debugger for our target .I tried this thread but still encountered the same issue.
We have also observed the tx and rx lines

Could you suggest additional debugging steps?

OK, I think MCU enter the BSL mode. MSP-FET and PC is in right configuration. 

The strange thing is that why the RX pin is low voltage? It should be high voltage... Can you check the external hardware setting?

Can you check if there is code in this range? If it is empty, you may need to refer to this app note to update this BSL:https://www.ti.com/lit/an/slaa450g/slaa450g.pdf

Hi Eason,

I have checked the voltage of TX and RX lines and they seem to be active we observed 3.3 on RX and 2.5 on TX 
regarding the BootLoader location, I attempted to read the BSL memory region (using Uniflash's memory browser), but the memory in those regions shows as 0xFFFF.

In the mentioned Application note , i couldn't find code for 6xx family so I attempted to flash the MSP430F673x_Family binary from the /Released_BSL_Images/BSL.00.07.05.04.txt folder using Code Composer Studio. After flashing, I checked the memory at 0x1000 and observed some values in that region.


Despite the above steps, I am still getting the "Unknown ACK value" error when running the BSL script.

Is my approach to flashing the BSL correct, or did I miss any key steps?

Why might I still be getting the "Unknown ACK value" error after flashing the BSL binary?

As I check the code is not downloaded. It is all to be 0x3FFF. Maybe the problem lies on the Erase setting.

For example, at 0x1000, the value should be 0x3C09.

Hi Eason,

I tried with this erase option , After loading a binary, I read the value 0x3C09 at this address, but after a power cycle, it reverts to 0x3FF


after powercycle

Can you try another device? The flash should not meet this problem....

I have tried with another board also same happened 
Here is what we tried:
1. through JTAG i have flashed the BSL.00.07.05.04.txt file using uniflash with mentioned erase option 
2. after power cycle , i observed 0x3fff at memory location 0x1000

I think when you write and read the memory, you need to do the selection as bellow.

If you create a new sesssion, and read the memory without do the selection, you will find the memory to be all 0x3FFF. 

Yes, i'm able to read the BSL memory 

Using this thread i'm able to flash However, when using the default Linux script for flashing i'm facing "Unknown ACK value"error again.

What could be the reason?
In fresh board can we try BSL UART flashing ,if yes how can we invoke the BSL sequence ?

Here is my further suggestion:

1. Can you try to use Unilflash+MSPFET and try again. Remember to choose the right setting.

2. Can you use an logic analysier to catch the wave? We need to intepret the communition. Not just the wave, get with oscillscope.

ok, Will check and let you know the results

Meanwhile, How can we achieve the BSL invoke through Test and RST pin via FTDI debugger? Any suggestion would be helpful

What do you mean with FTDI debugger? Do you refer to USB adapter? If so, you can refer to this link:https://e2e.ti.com/support/microcontrollers/msp-low-power-microcontrollers-group/msp430/f/msp-low-power-microcontroller-forum/847026/bsldemo-now-supports-generic-usb-to-uart-adapters-and-the-rocket

As I check it doesn't support F6

If you want BSL-scripter to support USB to UART tool. Please refer to this code and update the BSL-scripter source code