Building a Midi hat and jukebox using the Raspberry Pi

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Dr. Scott M. Baker has published a new build:

I picked up a Roland SC-55 to use with my retrocomputer setup recently, and I figured it would be cool to turn the thing into a standalone midi jukebox, so that no “computer” is required. I also figured this would be relatively easy, using a raspberry pi as the controller to drive the SC-55. My first step was to figure out how to get MIDI out from a raspberry pi. One option would have been to purchase a USB-MIDI adapter. This would have worked, but I really wanted to develop a native raspberry pi MIDI interface rather than using USB. MIDI is a fairly simple interface, and the raspberry pi has built in serial capability, so this ought not to be too difficult.

Project details can be found on Dr. Scott M. Baker’s blog.

Check out the video after the break.

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Free PCB Sunday: Pick your PCB

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We go through a lot of prototype PCBs, and end up with lots of extras that we’ll never use. Every Sunday we give away a few PCBs from one of our past or future projects, or a related prototype. Our PCBs are made through Seeed Studio’s Fusion board service. This week two random commenters will get a coupon code for the free PCB drawer tomorrow morning. Pick your own PCB. You get unlimited free PCBs now – finish one and we’ll send you another! Don’t forget there’s free PCBs three times every week:

Some stuff:

  • Yes, we’ll mail it anywhere in the world!
  • Be sure to use a real e-mail in the address field so we can contact you with the coupon.
  • Limit one PCB per address per month please.
  • Like everything else on this site, PCBs are offered without warranty.
  • PCBs are scrap and have no value, due to limited supply it is not possible to replace a board lost in the post

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App note: Grid-connected solar microinverter reference design

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A good read from Microchip on the theory behind inverter design connected to grip power. Link here (PDF)

There are two main requirements for solar inverter systems: harvest available energy from the PV panel and inject a sinusoidal current into the grid in phase with the grid voltage. In order to harvest the energy out of the PV panel, a Maximum Power Point Tracking (MPPT) algorithm is required. This algorithm determines the maximum amount of power available from the PV module at any given time. Interfacing to the grid requires solar inverter systems to abide by certain standards given by utility companies. These standards, such as EN61000-3-2, IEEE1547 and the U.S. National Electrical Code (NEC) 690, deal with power quality, safety, grounding and detection of islanding conditions.

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App note: On-grid solar microinverter on Freescale MC56F82xx/MC56F82xxx DSCs

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Application note from Freescale Semiconductor about microinverter solution develop together with Future Electronics. Link here (PDF)

In recent years, demand for renewable energy has increased significantly. The development of devices utilizing clean energy such as solar, wind, geothermal, and fuel cells attracts more and more attention. Solar energy harvesting is developing fast and will play a more important role as a global energy source. One of the ways to capture solar energy is via photovoltaic power generation systems, which are connected to the grid through power inverters. Therefore, many companies are focusing on development of photovoltaic grid-tie inverters. Freescale offers digital signal controllers, the MC56F8xxx family, that are well suited to ongrid solar inverter designs.

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Feather M0 express supersizing

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Dastels writes, “In my last post I described how I hacked a 2Mbyte SPI flash onto a Trinket M0 to give it the memory space for CircutiPython of one of the M0 Express boards. This time I supersized an M0 Express board, specifically a Feather M0 Express, although the same hack should work on a Circuit Playground Express.”

More details at Curmudgeoclast site.

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Free PCB coupon via Facebook to 2 random commenters

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Every Friday we give away some extra PCBs via Facebook. This post was announced on Facebook, and on Monday we’ll send coupon codes to two random commenters. The coupon code usually go to Facebook ‘Other’ Messages Folder . More PCBs via Twitter on Tuesday and the blog every Sunday. Don’t forget there’s free PCBs three times every week:

Some stuff:

  • Yes, we’ll mail it anywhere in the world!
  • We’ll contact you via Facebook with a coupon code for the PCB drawer.
  • Limit one PCB per address per month, please.
  • Like everything else on this site, PCBs are offered without warranty.

We try to stagger free PCB posts so every time zone has a chance to participate, but the best way to see it first is to subscribe to the RSS feed, follow us on Twitter, or like us on Facebook.

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A digital communication project using OFDM and 32-QAM

1OFDM system

Tahmid blogged about a digital communication project using OFDM and 32-QAM as their ECE4670 final project:

This builds on a previous lab, where orthogonal frequency division multiplexing (OFDM) is used with on/off keying to send data over the channel. This scheme achieved a data rate of about 14,000 bits per second with zero errors, resulting in a figure of merit of about 14,000. The high performance design utilizes orthogonal frequency division multiplexing (OFDM) and quadrature amplitude modulation (QAM) to achieve a figure of merit much higher than the previous lab.
The overall OFDM system block diagram is shown below (taken from Professor Wagner’s course’s Scribe notes)

See the full post on his blog.

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Pulse Oximeter functionality for a medical device

Pulse Oximeter on my finger-600

Alexander Lang writes:

The gentlemen for whom I’m developing this hardware for has requested some additional functionality. The additional functionality requested is a Pulse Oximetry measurement.  Pulse Oximetry is the measurement of a person’s pulse along with how much oxygen is present within their blood.  It is a common measurement made by medical practitioners to ensure their patients are in good health.  I suspect for the medical device, this information will be correlated with a person’s breathing to assess how well a person’s lungs are working and how much oxygen from the air is getting into their blood.

See the full post on his blog here.

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Pulse Oximeter functionality for a medical device

Pulse Oximeter on my finger-600

Alexander Lang writes:

The gentlemen for whom I’m developing this hardware for has requested some additional functionality. The additional functionality requested is a Pulse Oximetry measurement.  Pulse Oximetry is the measurement of a person’s pulse along with how much oxygen is present within their blood.  It is a common measurement made by medical practitioners to ensure their patients are in good health.  I suspect for the medical device, this information will be correlated with a person’s breathing to assess how well a person’s lungs are working and how much oxygen from the air is getting into their blood.

See the full post on his blog here.

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