This thread has been locked.

If you have a related question, please click the "Ask a related question" button in the top right corner. The newly created question will be automatically linked to this question.

MSP-EXP430FR4133: Does a power status led illuminates when powering the MSP-EXP430FR4133 with a battery?

Part Number: MSP-EXP430FR4133

Hello everybody,

I'm trying to get into embedded systems programming and I have to choose a development board.

I also have a little project I'd like to implement. I'd like to make a kind of countdown/timer that I will use as an alarm clock. This is a project I think could teach me a lot of things, and I also really need an alarm clock that doesn't stop blinking until I get up (so that, as soon as I open my eyes, I know if it's time to get up or not).

Anyway, I have two questions, that are related. I'm going to need to power the device with a battery. Can it be done? If so what kind of battery and battery holder do you advise ?

More importantly, can this development board can be powered on battery without any led turned on? I want to use this device at night, as an alarm clock, and I have trouble sleeping with even the slightest ammount of light in the room. So I want to make sure it's possible to have it running during the night without it emitting any light. Most development boards I've seen seem to have a kind of power status led that can't be deactivated and I'd like to know if the MSP-EXP430FR4133 is an exception to this rule.

Thanks to all.

  • There is no power LED on the MCU side of the "dotted line". This is a feature, since you can measure your program's power (current) draw by removing all the jumpers on J101 and connecting power to 3V3/GND on the MCU side.

    There is no special provision for running that particular Launchpad on a battery. I expect you could connect a 3V battery pack to 3V3/GND on J101 (MCU side), but you couldn't use a Li-Ion battery pack since that's 3.7V (up to 4.2V) and there's no regulator (also a feature).

  • Thanks for the reply, Bruce. Your reply is teaching me a lot.

    I have absolutely no experience with electronics, and I've never seen the MSP-EXP430FR4133 other than in photo, so far, so this took me a bit of time to process.

    I see what you mean about the power led. It's on the other side of the dotted line, the side that interfaces with the computer for the debugging. So, it's totally on the opposite side of the user leds. I guess I'll just have to cover that part of the board at night.

    It took me a while to realize what you meant by J101, but now I see you're refering to this block of black plastic that the dotted line is crossing. I had absolutely no idea these little black plastic things were jumpers, that's good to know. So, if I remove one of these jumpers, I guess this uncovers two small metal sticks (I'm not sure if I should call those pins).
    So you say I have to connect the 3V3 and GND pins from the MCU side of the board to the battery, right?
    While trying to understand what the J101 block was, I stumbled upon these schemas that are about powering the device:
    It seems there are actually 3 points of connection to make?
    What do you think? You think it would work with just connecting the 3V3 and GND pins of the J101 block (MCU side) to the battery?

  • Yes, a jumper is used to connect two pins together. In this case, they're used to pass signals between the USB and MCU sides.

    There's no need to connect the 5V pin -- that's purely a convenience in case someone wants 5V (from the USB) on the MCU side. I usually remove the 5V jumper and leave it off, just to avoid mistakes.

    I don't recall whether I've connected a battery to the 3V3/GND pins (probably), but I have connected an external power supply. As long as it's a 3V battery pack you should be fine. You'll want to remove all the jumpers on the J101 ("bridge") block, so you don't back-power the programmer circuit. Once you do that (and disconnect the USB) you'll see that the power LED will go out.

    Stating the obvious: Load (and try out) your program code before you disconnect everything, since you'll be disconnecting the programmer/debugger. 

  • For someone with no electronics experience, it would probably be best to get one of the USB battery power packs and power via the USB port.

    In this case, you would have some LED's above the dotted line that will illuminate, but you can focus on the software. Once that gets going you can get a second launchpad you can hack and switch to battery power.

  • Thanks Bruce, that was extremely helpful. And I hadn't realized until your second reply that the power status LED from the board would go out when removing the USB power and powering only using a battery. That is great news. Thanks also for the advice about removing all the other jumpers of the J101 block. I wouldn't have thought of doing that.

    Bruce McKenney47378 said:
    Stating the obvious: Load (and try out) your program code before you disconnect everything, since you'll be disconnecting the programmer/debugger. 

    What do you mean? I sure plan to develop using the USB cable until I have something that works. After that (when my timer is working), I plan to unplug the USB cable, remove the jumpers at J101 and then, connect a battery. I hope I'll have a totally autonomous timer at this point, that I can use without the USB. But I'd also like, maybe some days later, to be able to reprogram the chip with other programs. I guess I should be able to do that, or do you mean it is not possible to put the jumpers back after you remove them?

  • Yes, you can put the jumpers back on whenever you want. I was 99% sure you knew this, but I "stated the obvious" to cover the other 1%.

**Attention** This is a public forum