Using the TI LaunchPad from your KoP

[philso]

I am contemplating using the TI MSP430 Launchpad for a project I have in mind. I would like to use this as an opportunity to learn to use TI microcontrollers. Please advise if the following is workable.

I would like to build a device to control the DC current to a load using a PWM output stage and monitor the load current and voltage using two of the ADC inputs. I would want to store the time-stamped data, most likely on an SD Card. The time-stamp does not have to be the actual time. The time since the start of the sequence would be sufficient. I was considering using a touch screen LCD for the user interface. I found the following Booster Packs on the 43oh web site. I am comfortable designing the switching circuitry myself since that is what I do for my day job.

http://forum.43oh.com/topic/1700-sdcard-booster-pack/

http://forum.43oh.com/topic/6149-24-...t-touch-panel/

[ILAMtitan]

Originally Posted by philso

I am contemplating using the TI MSP430 Launchpad for a project I have in mind. I would like to use this as an opportunity to learn to use TI microcontrollers. Please advise if the following is workable.

I would like to build a device to control the DC current to a load using a PWM output stage and monitor the load current and voltage using two of the ADC inputs. I would want to store the time-stamped data, most likely on an SD Card. The time-stamp does not have to be the actual time. The time since the start of the sequence would be sufficient. I was considering using a touch screen LCD for the user interface. I found the following Booster Packs on the 43oh web site. I am comfortable designing the switching circuitry myself since that is what I do for my day job.

http://forum.43oh.com/topic/1700-sdcard-booster-pack/

http://forum.43oh.com/topic/6149-24-...t-touch-panel/

Philso,
The Launchpad would be a perfect platform for what you're trying to do. The only issue you might run into using the booster packs you've found that I see is that they will both probably use the same SPI port. You would have to double check the pin-outs to ensure that the chip select lines are on different pins so you can mux them properly. I've worked with RobG and BlueHash from 43oh before though, and they are both great resources.

It looks like RobG made a booster pack that integrates the SD and LCD into a single design: https://www.tindie.com/products/RobG...d-card-socket/
You might want to take a look at that one to see if it will meet your requirements.

Another consideration to make is how accurate you need your current measurements. The Launchpad that we put in the KoP is the MSP430F5529, which has 12 bit SAR converters. We just recently launched the MSP432P401 LP which has 14bit converters that might give you some additional dynamic range/accuracy if needed. In addition, that board has the new MSP432 processor, which is a 48MHz 32bit Cortex M4F. The additional clock speed should also give you higher resolution PWMs (but I haven't looked into this specific feature).

Both of the Launchpads listed will also include an internal RTC capable of making accurate time stamps for your data logger. You can either set it to the current data/time, or just use it in free run mode as you described. I'm not personally familiar with designing and operating a DC current source via PWM, but I can ask around the 430 team to see if anyone has information I can share if that would help.

[philso]

Originally Posted by ILAMtitan

Philso,
The Launchpad would be a perfect platform for what you're trying to do. The only issue you might run into using the booster packs you've found that I see is that they will both probably use the same SPI port. You would have to double check the pin-outs to ensure that the chip select lines are on different pins so you can mux them properly. I've worked with RobG and BlueHash from 43oh before though, and they are both great resources.

It looks like RobG made a booster pack that integrates the SD and LCD into a single design: https://www.tindie.com/products/RobG...d-card-socket/
You might want to take a look at that one to see if it will meet your requirements.

Another consideration to make is how accurate you need your current measurements. The Launchpad that we put in the KoP is the MSP430F5529, which has 12 bit SAR converters. We just recently launched the MSP432P401 LP which has 14bit converters that might give you some additional dynamic range/accuracy if needed. In addition, that board has the new MSP432 processor, which is a 48MHz 32bit Cortex M4F. The additional clock speed should also give you higher resolution PWMs (but I haven't looked into this specific feature).

Both of the Launchpads listed will also include an internal RTC capable of making accurate time stamps for your data logger. You can either set it to the current data/time, or just use it in free run mode as you described. I'm not personally familiar with designing and operating a DC current source via PWM, but I can ask around the 430 team to see if anyone has information I can share if that would help.

Thanks for your quick reply, Bart.

The MSP432P401 LP, with the 14-Bit ADC and PWM and internal RTC looks very attractive at just a few dollars more.

I had chosen the LCD with the touch screen to avoid needing to add a keyboard or keypad. I will check the chip select lines used by the two booster packs. I am guessing that if they conflict, I should be able to modify one of them to use a different GPIO pin.

I have done a bit of reading about the SD card booster pack and am a bit confused. It appears that the software currently can only read from the SC card and cannot write a file or it cannot create a file from scratch on the SD card. Is this true?

[ILAMtitan]

Originally Posted by philso

Thanks for your quick reply, Bart.

The MSP432P401 LP, with the 14-Bit ADC and PWM and internal RTC looks very attractive at just a few dollars more.

I had chosen the LCD with the touch screen to avoid needing to add a keyboard or keypad. I will check the chip select lines used by the two booster packs. I am guessing that if they conflict, I should be able to modify one of them to use a different GPIO pin.

I have done a bit of reading about the SD card booster pack and am a bit confused. It appears that the software currently can only read from the SC card and cannot write a file or it cannot create a file from scratch on the SD card. Is this true?

Good catch, I didn't even notice that the other one didn't have a touch screen.

One of our design partners also did an SD boosterpack which has a configurable CS pin location so you can avoid having to modify the hardware: http://boardzoo.com/index.php/booste...l#.VUt-PflVgZ4

Regarding the library, I know that PetitFS is a but limiting, but it was written to fit onto very small devices. The AdaFruit library should be compatible however: https://github.com/adafruit/SD
I got the examples to compile after removing the block of code where it wait's for the serial connection to enumerate on the Arduino, but I don't have the hardware on hand to test it. I'll try to snag a Boosterpack from someone around here to give it a whirl.

[philso]

One of my coworkers suggested writing a Visual Basic program to run on a Windows computer to collect the data rather than saving the data onto an SD card. It would also eliminate the need to write so much low-level user interface software to run on the microprocessor. I am looking into either using a USB, WiFi or BlueTooth connection. Do you have any recommendations.

Having looked at the other LaunchPads, I am also considering using the LAUNCHXL-F28069M. It is similar to microcontrollers I have worked with on some of my boards at work (TMS28027 and TMS28335). I also like that the LAUNCHXL-F28069M can accommodate two Booster Packs and it's ability to perform math functions in one or two clock cycles.

[ILAMtitan]

If you're going to have a computer next to the data logger that's not a bad idea. Every LaunchPad has back channel serial that can be used to send data back to the computer pretty easily. C# is pretty easy to cobble some kind of interface together in, but you can also just use a serial terminal and copy the data to a txt or csv for processing from there. Some of the terminal program (I use RealTerm for this) can dump everything it receives to a txt natively, which might be sufficient.

If you're already familiar with the TMS2xxx devices, I would stick with that and use the back channel. If you do want to move to WiFi, the CC3200 LP can be used to stream data back over the network pretty easily, but you would have to setup a socket server or something on the PC side.

[philso]

It seems that for the USB interface, I could use the USB interface (FTDI2232H) that is already on the LP and connects to the JTAG port and an SCI port on the TMS320F28069. It also seems that if I remove/open JP1 and JP3, the USB interface would "float" and be powered from the host computer.

Thanks for the recommendation for RealTerm. It would be a great way to get started. Later, I would still want to implement some sort of Visual Basic or Visual C program running on the host to set operation modes and monitor progress in a way that is more user friendly.

[Pugsly]

Regarding the "Set Output" of the joystick I am trying to light up an indicator using the Launchpad that was included in last years kit and I can't for the life of me figure out how to wire this up in Labview.

So say for instance I want to light a LED on the launchpad Red or Blue depending on what alliance we are on. Anyone have any ideas on how do do that?

[wt200999]

How do you have it wired up to the LaunchPad? Do you have one red LED and one blue LED, or an RGB LED, or some kind of addressable LED strip?

I posted a few examples of how to use the WPI_JoystickSetOutputs.vi in a thread here. You can use the output from the Get Alliance.vi to select a different value for the output vi.