Turning the Stellaris Launchpad into a logic analyzer

acquisition

If you have a Stellaris Launchpad sitting around, have a go at using it as a logic analyzer

The Stellaris logic analyzer is based upon this earlier build that took code from a SUMP comparable Arduino logic analyzer and ported it to the much faster and more capable Stellaris Launchpad with an ARM Cortex 4F processor.

This build turns the Launchpad into a 10 MHz, 8-channel logic analyzer with a 16 kB  buffer comparable with just about every piece of software thanks to the SUMP protocol. Even though the ARM chip in the Launchpad isn’t 5 Volt tolerant, only pins 0 and 1 on Port B are limited to 3.6 Volts. All the other pins on Port B are 5 Volt tolerant.

Not a bad piece of work to turn a Launchpad that has been sitting on your workbench into a useful tool.

MOD player for the Stellaris Launchpad

[Ronen K.] wrote in to tell us about the MOD playing Stellaris Launchpad project he recently completed. A MOD is a sound file for the computers of days long gone. But you’ll certainly recognize the sound of the 8-bit goodness that is coming out of this device.

To understand how a MOD file stores samples you might want to glance at the Wikipedia page. There are a ton of these files out there, but this implementation is meant for files with only four channels. For now the only external hardware used is an audio jack which needs a ground connection and a PWM signal on each of the two audio channels. [Ronen] is storing the files in flash memory rather than using an SD card or other external storage. This leaves 213k of space for up to six files that can be selected by the user buttons which cycle forward or backward through the list. See this demonstrated after the break.

The project ports existing code from an STM32 application. Since that is also an ARM microcontroller there’s not a ton of work that needed to be done. But he did have to write all of the PWM functionality for this chip. This PWM tutorial turned out to be very helpful during that process.

[Read more...]

Hackaday Links: November 9, 2012

Yeah, it’s like Twitter but actually cool

Thingiverse – still the best place on the Internet to find cool 3D models to print out – has gone all Web 3.0 with their new Dashboard feature. Basically, you can think of this as Thingiverse’s version of Twitter. The dashboard allows you to see the latest updates from people you like, follow people, categories, and tags, and check out your all-important ‘who’s following me’ stats. Yes, to the Hackaday crowd it may sound a little lame, but it’s a great way to winnow the (awesome) wheat from the (slightly less awesome) chaff.

Hey, we goofed. And not by using the same image twice

Remember when we jumped on the Occupy Thingiverse bandwagon? Well, there were questions about the Thingiverse Terms of Service and confusion that Makerbot actually owns everything uploaded to Thingiverse. That’s completely wrong according to Makerbot’s lawyer [Rich McCarthy]. The whole issue dealt with “Moral Rights or attribution” – a French legal doctrine that isn’t part of US law (or the law of any English-derived legal system as far as we can tell). Yeah, we goofed.

Now u cn snd SMS msgs wit n ‘ino & cell sheld

[Meir] sent in a cellular library for microcontroller projects that allows for simple sending and receiving of SMS messages. Yes, it’s been done before, but [Meir] hid all the hardware interaction with the cellular shield – a good design practice – to make the code nice and tidy.

And you thought PVC was bad…

Just in time for Thanksgiving, [Lou] shows us the fastest way to make mashed potatoes: an oxygen and propane powered potato gun. The build uses oxy and propane tanks you can pick up for a few bucks at any hardware store, steel pipe for the barrel, a grill igniter, and a few pipe fittings. It’s awesome, and we’ve got to hand it to [Lou] for this one. Now to build one and test it out on our indestructible test dummy.

It’s just like the Raspberry Pi! They’re that backordered!

Remember the Stellaris Launchpad, the very cool (and very inexpensive) ARM dev board put out by TI? Yeah, they’re shipping now. News of this comes from [Ryan Holtz] at Autodesk after the FedEx guy came knocking a few days ago. The good news is they’re shipping, the bad news is the price increased slightly to $13.

 

PWM on the Stellaris Launchpad

[Joonas] has been following TI’s ‘getting started’ tutorials for their new Stellaris Launchpad. Everything had been going swimmingly until [Joonas] reached the fourth tutorial on interrupts. To the ire of LEDs the world over, implementing PWM on the new Stellaris Launchpad is a somewhat difficult task. After banging his head against the documentation for hours, [Joonas] finally cracked his PWM problem and decided to share his discoveries with the world.

The Stellaris has a PWM mode for its six hardware timers, but unfortunately there are no PWM units on the chip. Solving this problem required making two 16-bit timers out of a single 32-bit one. This allowed [Joonas] to specify a ‘load’ and ‘match’ value.

After coding this up, [Joonas] discovered the PWM timer only works on two of the Launchpad’s pins. Hours of Googling later, he had real PWM on his Stellaris Launchpad.

Given the amount of time [Joonas] spent on this problem, we’re glad to help all the other frustrated Stellaris tinkerers out there by sharing this.

Debugging the Stellaris with OpenOCD

It looks as though Texas Instruments are really reaching out to the hacker community with their new ARM-powered Stellaris dev board. On the Stellarisiti forums, a member asked about the debugging options for the Stellaris board. The Stellaris already features an In-Circuit Debug Interface (ICDI), but unfortunately it’s a little hard to get working in Linux-ey environments.

One of the devs for the Open On-Chip Debugger was already talking with TI to get the ICDI spec released for the Stellaris board. TI released the info, and after quite a bit of work, everything is open for all to see.

Right now, OpenOCD support for the Stellaris is still incomplete, but there is an project up on the Gits that allows for multi-platform development for TI’s new board.

Needless to say, getting everything up and running is still a chore. That’s not really a concern, though; the Stellaris has only been around for a few months and it takes devs time to put all the required tools into nice, neat packages. We’re just glad TI is being so forthcoming with the relevant documentation, lest development becomes a million times harder.

LiPo Powered Stellaris Launchpad

Want mobile power for your Stellaris Launchpad development board? [Philipp] was looking to add some lithium power for the Launchpad. He used an off the shelf single cell LiPo battery and connected it to the 5V rail of the Launchpad board. It didn’t work.

So [Philipp] started looking through the schematics and noticed that the regulator was working fine, but the Stellaris wasn’t starting up. He tracked down a voltage supervisor connected to the Stellaris reset pin. After some investigation, it was clear that this supervisor was holding the device in reset.

The solution is a quick and dirty hack: cut the trace that connects the reset line to the voltage line. With this modification, the device starts up from the LiPo without any issues. [Philipp] does note that you should be careful about battery under-voltage and over-voltage. This hack doesn’t handle charging the LiPo battery, but we’ve discussed that in the past.

Using StellarisWare with the Launchpad

In our last Stellaris how-to we got the board working and set some registers to turn on the LED. This time we’ll start using StellarisWare Driverlib, which provides drivers for the microcontroller’s peripherals including GPIOs, UARTs, ADCs, and so on. These libraries make it easier to control the peripherals. We’ll build the Driverlib project, create a project from scratch to use the library, and run a simple LED blinking example.

[Read more...]

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