June 26, 2014
I design my first Pi MIDI interface way back in 2012 while I was waiting for my first Pi board to arrive.
It’s went through several revisions since then and now looks like this:
The circuit is now completely 5V as per the original MIDI specification but the MIDI IN is 3.3V compatible with the Pi via a voltage divider circuit.
OK that’s the hardware what about the software?
Getting a MIDI 31250 Baud Rate on a Pi is not easy as it should be as 31250 is not a standard Pi baud-rate. But you can trick your Pi into it if you overclock (or rather underclock) the UART clock.
Start a terminal session and type:
sudo nano /boot/config.txt
Add these lines to the end of the file
# Change UART clock to 2441406 for MIDI 31250 baud rate
save and exit.
Once saved reboot your Pi.
Next we need to stop the serial UART being used by Raspbian for the shell console. Check my previous post “MiniPIiio RS232 set-up” on how to do this.
Finally we need to add the following to “cmdline.txt”
After doing all of this we should be ready to connect a MIDI keyboard or synth to our Pi.
Again I hope to have it stocked in out our store on Tindie soon:
June 24, 2014
Here’s a photo of a finished RPi-X PIAC experimenter module:
OK what does PIAC stand for?
PIAC = Pi Industrial Automotive Controller
It’s a Pi expansion shield that has 4x Change Over (CO) relays, 4x Opto Isolated Digital inputs and 4x 0V to 10V Analogue Inputs. There’s also a RS485 interface to communicate with industrial networks.
You can use it to learn about industrial control or perhaps even use it on your own small control projects.
I hope to have it stocked in our Tindie store soon:
May 13, 2014
Another box of new boards arrived from DirtyPCBs.com today.
In the box where 4, yes 4 sets of PCB’s.
In the photo, the big PCB at the back is RPi-X PIAC. On the photo front row, on the left is MiniPiio LED Breakout, in the centre is MiniPiio BOP4 and to the right is MiniPiio PWM16
RPi-X PIAC is our latest RPi-X experimenter board. The acronym IAC is commonly used to describe an industrial automation and control system and adding a P in this case makes it a Pi Industrial Automation and Control :-)
PIAC has 4x SPCO Relays rated at 2A, 4x opto-isolated digital inputs, 4x 0-10V Analogue inputs and finally a RS485 communications port. So with the RPi-X PIAC you can learn about industrial control or perhaps use it for your own small industrial project.
MiniPiio LED Breakout uses the popular MAX7219 8-digit (64x LED) LED display driver chip to breakout all 64 LED outputs to 8 rows of pin headers. From these pin headers you can plug in individual LED’s to make whatever LED display layout you want. It’s a shame its not Christmas as I think it would make a great blinky LED Christmas tree :-)
MiniPiio BOP4 or Board of Pots (or should that be “Bored of Pots”) has 4 potentiometers (3x rotary and 1x slider) and connects them to a 4-ch MAX3004 ADC. I think it will a great physical user interface. It’ll probably make a great companion to the LED/Switch MiniPiio SimpleIO we showed off a few months back. Of all the new boards I think this is my favourite :-)
The final new PCB, is MiniPiio PWM16. I think its name gives it away. It’s a hardware based 16-channel PWM add-on board using the popular PCA9685.
As always you’ll find them on my Tindie store in the next few days.
April 29, 2014
A new batch of PCB’s arrived today.
There were two new Raspberry Pi add-on boards in the box.
The first board is a 2-channel Type-K Thermocouple converter based on the MAX31855 chip.
The second board is RF Transceiver based of HopeRF popular RFM12B module.
I’ll plan to build them up in the next few days and if all goes well I’ll list them in our Tindie store.
April 14, 2014
MiniPiio SimpleIO is just that, a add-on board with simple inputs and outputs. It features 8x LED’s and 8x tactile switches. The Pi’s GPIO4/17/18/22/23/24/25/27 are each connected to an LED and switch.
You have 8x signals you can mix and match with whatever combination of LED’s or switches your design needs. So if you need more indicators you could have say 6x LED’s and 2x switch inputs and like wise, if you need more inputs than outputs you could have 5x switch inputs and 3x LED outputs.
You can find them at our store on Tindie.
Note: LED and Switches sharing the same GPIO so are not designed to used simultaneously.
April 14, 2014
Eh? Why another prototyping board? Isn’t the CM I/O a prototyping board already?
Yes, it is. And the CMIO ProtoBoard is a prototyping board for you to build circuits directly on with can be used with the CM I/O board and Compute Module.
Same as blinking an LED is the first code you write for a new embedded system, designing a prototyping board is often the first thing I do with every new system I work with.
Why, I hear you ask?
- I want some thing I can quickly build permanent circuits with, so the days of loose wires spoiling my days are far behind.
- I want some thing that is cheap and cost effective. I want to experiment with different circuit designs, without worrying if I’ve wasting money every time I start a something new.
- I want some thing that when its built looks decent and not a heap of wire
Some of the dimensions and connector positions I’ve had to guess at but here’s a quick layout of what I’ve done so far:
April 6, 2014
MiniPiio Thermocouple is a single channel temperature measurement add-on board using Type-K thermocouples.
The MAX31855 is a sophisticated thermocouple-to-digital converter. It features a built-in 14-bit analog-to-digital converter (ADC) for thermocouple measurement. In addition it also contains a cold-junction sensor for compensation temperature sensing and correction.
The MAX31855 resolves temperatures to 0.25°C. It allows readings as high as +1800°C and as low as -270°C and exhibits thermocouple accuracy of ±2°C for temperatures ranging from -200°C to +700°C for K-type thermocouples.
– Works with any K type thermocouple
– Temperature range = -200°C to +1350°C output
– Resolution 0.25 degree
– Accuracy is ±2°C
– Internal cold junction temperature reading
– SPI bus interface
– Two SPi Chips Selects (!CE0 and !CE1)
You can find it at our Tindie store