MSP430F54xx initial program, clock settings, and pin states

Sage Radachowsky

Other Parts Discussed in Thread: MSP430F5438, MSP430F5419

Hello,

My simple question is, what is the initial setting of the MSP430F5438 or MSP430F5419 in regard to the clock and to the program that it runs when it comes from the factory?

My guess on clock is that it uses the internal ~ 32 kHz oscillator. But if there is a crystal tied to XT1 and XT2, does it then try to use it?

My guess on program is that it simply goes into some low power mode and sleeps. Of course, I will program the devices, but I typically program in place and I would like to know what it is running the first time that I apply power, when it's on my circuit board.

I also assume that all peripherals are off, and that all pins are set as inputs in digital mode. Is this correct? More specifically, for example, are the pins that have the ADC input function really acting as digital I/O inputs, and therefore they could draw some current if they are connected to an intermediate voltage? On my board, for example, I have a 2.048V reference connected to the Vref+ pin. Before I first program the chip, will this cause a problem, and how much current could it possible draw?

I have not found the information about either of these in the data sheets. Can someone please point this out to me as well?

Thank you for any help on my several questions, expert friends.

Sage

over 15 years ago

0 Sage Radachowsky over 15 years ago

Prodigy 180 points

Pardon me... Instead of XT1 and XT2, I meant to say XIN and XOUT.

Sage

0 chris_m over 15 years ago

Expert 1725 points

Hi Sage,

Check out the 5xx user guide for initial settings of pins and clock.

It looks like the pins will initially be inputs so yes there could be some current draw - the amount will depend upon your hardware, you'll have to provide more information before anyone can quantify it. If you want to protect against this consider using other I/O pins with (large) pullup/down external resistors to enable the ADC signals and reference only when you want them.

I can't say for sure what will be on the chips when they ship from the factory but I assume they will be blank (i.e. all FFs). Having 0xFFFF in the reset vector will cause a device to keep resetting, I very much doubt they will be resting in a low power state. Try reading the memory contents of a new device - this will show what it is doing.

Chris.

0 Priya Thanigai over 15 years ago

TI__Mastermind 26380 points

Hello,

The initial settings are all available in the User's Guide. Just look under each individual register bit setting for a [0] or [1] indicating the state after reset.

The MCLK (system clock) defaults to DCOCLKDIV ~1MHz.

ACLK (auxilliary clock) defaults to the crystal on XT1 but the fault flag needs to be cleared before XT1 can be used - so until the faults are cleared the REFO (internal 32KHz) is used.

If there is no user code programmed to the device - the boot code checks for a reset vector and if it has not been programmed - the device is placed in LPM4.

All peripherals are off and GPIO's are input (floating) as Chris described.

Sage Radachowsky said:
More specifically, for example, are the pins that have the ADC input function really acting as digital I/O inputs, and therefore they could draw some current if they are connected to an intermediate voltage?

--> Yes

A good place to find some of this info is by taking our MSP430 F5xx training available at: http://processors.wiki.ti.com/index.php/MSP430_5xx_One_Day_Workshop

There is a presentation available under : Instructor Materials.

Regards,

Priya

0 Sage Radachowsky over 15 years ago in reply to Priya Thanigai

Prodigy 180 points

Hi Priya,

Thank you very much for the information.

Knowing that the microcontroller enters LPM4 if it has not yet been programmed is quite useful information. That is the main thing that I wanted to find out.

That is a very sensible action for the bootloader to take.

Sage

0 nikhil n mane over 15 years ago in reply to Priya Thanigai

Expert 1015 points

hi priya

please see this post and tell me something

http://e2e.ti.com/support/microcontrollers/tms320c2000_32-bit_real-time_mcus/f/171/t/85914.aspx

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MSP low-power microcontroller forum

MSP430F54xx initial program, clock settings, and pin states