[Avian] has been using STM32 ARM processors to sample RF for a variety of applications. At first, he was receiving relatively wide TV signals. Recently, though, he’s started dealing with very narrow signals and he found that his samples had a lot of spread in the frequency domain that he didn’t expect.
What followed was some detective work that resulted in a determination that phase noise was the culprit. But why? [Avian] took some measurements and noticed that the phase noise almost exactly matched the phase noise specification for the STM32’s phase locked loop (PLL).
Unfortunately, there didn’t seem to be a good way to avoid using the PLL without major changes to the rest of the circuit. However, it was quite the learning experience and something to be aware of when counting on built-in converters for high-accuracy measurements.
One of the best things about this post is the references to more information. There’s a great explanation of phase noise, as well as a specific application note about clock jitter and analog converters.
We’ve talked about phase noise in direct digital synthesis a few times. But usually, it is pretty obvious like when you are asking a CPU to double as an RF transmitter. [Avian’s] post was a bit more of a detective story.
The Teensy is a powerful ARM-based development board with loads of features that can do fun stuff with USB as well. Like many dev boards, it uses a less powerful processor as an interface. Teensy designer [Paul Stoffregen] added a debug header to allow direct SWD JTAG access to the main chip, but the interface microcontroller has to be silenced for that to work, and the code to do so is still in progress.
Impatient, [Erich Styger] documents the changes he made to add support for the J-Link SWD protocol by removing the offending NXP Kinetis KL02Z that serves as the as the onboard interface and bootloader that helps the Arduino IDE talk to the K64F which is the main chip. After the KL02Z was removed, [Erich] populated the debug headers and then wired up the Segger J-Link to the board and tested it out with Eclipse, GDB, and standard SWD debug tools.
The end result is a Cortex M4F board that can work with standard tools at a third of the price of the Kinetis’ development board. [Paul Stoffregen] confirms that the debugging functionality will be added to the bootloader code soon but until then, a hardware hack is a working, if brutal, approach to debugging on the platform.
More information on the JTAG interface is available for the interested. And if Teensy isn’t your thing, you might consider an STM32-based development board.
[Otermrelik] wanted to experiment with the Teensy audio library and adapter. That, combined with his 3D printer, led to a very cool looking build of the teensypolysynth. The device looks like a little mini soundboard with sliders and 3D printed knobs. You can see (and hear) it in the video below.
The Teensy audio library supports several output devices including several built-in options and external boards like the audio adapter used here. The library does CD-quality sound, supports polyphonic playback, recording, synthesis, mixing, and more.
Continue reading “Teensy and 3D Printer Make Beautiful Music Together”
The Pine A64 was a 64-bit Quad-Core Single Board Computer which was kickstarted at the tail end of 2015 for delivery in the middle of 2016. Costing just $15, and hailed as a “Raspberry Pi killer,” the board raised $1.7 million from 36,000 backers. It shipped to its backers to almost universally poor reviews.
Now they’re back, this time with a laptop—a 11.6-inch model for $89, or a 14-inch model for $99. Both are powered by the same 64-bit Quad-Core ARM Cortex A53 as the original Pine A64 board, but at least Pine are doing a much better job this time around of managing user expectations.
Continue reading “Hands on with the Pinebook”
We’ve often heard (and said) if you can’t hack it, you don’t own it. We noticed that [tmbinc] has issued a call for help on his latest project: developing new firmware and an FPGA configuration for the Rigol DS1054Z and similar scopes. It isn’t close to completion, but it isn’t a pipe dream either. [tmbinc] has successfully booted Linux.
There’s plenty left to do, though. He’s loading a boot loader via JTAG and booting Linux from the USB port. Clearly, you’d want to flash all that. Linux gives him use of the USB port, the LCD, the network jack, and the front panel LEDs and buttons. However, all of the actual scope electronics, the FPGA functions, and the communications between the processor and the FPGA are all forward work.
Continue reading “Help Wanted: Open Source Oscilloscope on Rigol Hardware”
If you’ve ever been curious if there’s a way to program microcontrollers without actually writing software, you might be interested in FlowCode. It isn’t a free product, but there is a free demo available. [Web learning] did a demo of programming a Nucleo board using the system. You can check it out below.
The product looks slick and it supports a dizzying number of processors ranging from AVR (yes, it will do Arduino), PIC, and ARM targets. However, the pricing can add up if you actually want to target all of those processors as you wind up paying for the CPU as well as components. For example, the non-commercial starter pack costs about $75 and supports a few popular processors and components like LEDs, PWM, rotary encoders, and so on.
Continue reading “FlowCode Graphical Programming”
A new single-board computer by Orange Pi has popped up for sale on AliExpress. The Orange Pi 2G-IoT is designed to compete with the Raspberry Pi Zero, and if specs are anything to go by they have done a nice job.
There are a lot of options for extra small single board computers these days and there’s a growing list at the lowest price points. Let’s call it the sub-$20 cost range (to quell the argument of shipping fees). We have seen C.H.I.P., the Raspberry Pi Foundation released the Pi Zero W (an update to the Zero line that included WiFi and Bluetooth), the already available Orange Pi Zero (which was featured in a project on Monday), and now add to that list the unfortunately named Orange Pi 2G-IoT.
The 2g-IoT is sporting an ARM Cortex-A5 32bit clocked at 1GHz with 256MB DDR2 RAM. It’s nice to see 500 MB of on-board NAND to go along with an SD card slot for larger storage. It also has a CSI camera connector, WiFi, Bluetooth, an FM Radio and GSM/GPRS with a sim card slot on the bottom. It is pin compatible with Raspberry Pi’s almost standardized GPIO layout.
All this for $10 is quite impressive to say the least, especially the addition of GSM/GPRS. Will it kill Raspberry Pi Zero W sales? We think not. While the Orange Pi’s are great little computers, they don’t have the community support that is afforded to Raspberry Pi products making for less support online when you run into a problem. That’s if you can even get the thing running in the first place. The Orange Pi’s website has not yet been updated to reflect the new release. However if you are interested in getting one for yourself right now, head over to your favorite Chinese electronics supplier.
[via Geeky Gadgets and CNX]