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by blippy
Fri Jun 28, 2019 9:23 pm
Forum: Interfacing (DSI, CSI, I2C, etc.)
Topic: wiringPi SPI: what determines SS?
Replies: 0
Views: 77

wiringPi SPI: what determines SS?

I'm puzzled: how is the slave selected by wiringPiSPIDataRW()? I presume you have to set the slave pin low yourself, although I have NEVER seen any example of where this is done. I notice on the pinout that there is a CE0 and CE1 for both SPI0 and SPI1. Is that what you use for the "channel" paramet...
by blippy
Thu Jun 27, 2019 8:00 pm
Forum: Interfacing (DSI, CSI, I2C, etc.)
Topic: I2S: what's the rationale behind changing WS on LSB?
Replies: 2
Views: 251

Re: I2S: what's the rationale behind changing WS on LSB?

One thing that springs to mind is that when the WS changes, receiver knows that the bytes for the channel have been completed, so it can do whatever it needs to. That way, if transmitter stops transmitting, receiver does not have to guess if the bitstreams for that channel has been completed. Seem r...
by blippy
Thu Jun 27, 2019 6:42 pm
Forum: Interfacing (DSI, CSI, I2C, etc.)
Topic: I2S: what's the rationale behind changing WS on LSB?
Replies: 2
Views: 251

I2S: what's the rationale behind changing WS on LSB?

I'm looking at the timing diagram for I2S: https://en.wikipedia.org/wiki/I%C2%B2S If, for example, you are transmitting the left channel, WS (word select) changes from 0 to 1 when you transmit the LSB (least significant bit). What's the rationale behind this? I would have thought it would be more lo...
by blippy
Thu May 30, 2019 7:56 am
Forum: Python
Topic: A Pauser class
Replies: 1
Views: 514

A Pauser class

Elevator pitch : Pauser encapsulates the notion of state change, concurrency and delays. It is portable across languages, requires no special language features or infrastructure. Motivation : So I had been tooling around trying to get concurrency working, wanting delays, and trying to debounce a sw...
by blippy
Mon Jan 07, 2019 10:19 pm
Forum: Other projects
Topic: STICKY: The projects list. Look here for some ideas.
Replies: 232
Views: 377987

Re: STICKY: The projects list. Look here for some ideas.

ABACUS CLOCK This is a slight twist on a binary clock: an abacus clock. An abacus clock is easier for a human to decipher. It is made with an Arduino, a RTC clock module, and an Adafruit 8x8 LED backpack. It looks cool, and the matrix is just about the right size for such a project. Video: https://y...
by blippy
Mon Jan 07, 2019 12:58 pm
Forum: Other projects
Topic: STICKY: The projects list. Look here for some ideas.
Replies: 232
Views: 377987

Re: STICKY: The projects list. Look here for some ideas.

TAKE YOUR MEDS! This little project https://github.com/blippy/rpi/tree/master/pills reminds you to take your medications throughout the day. You set up as many alarms as you need, and at the allotted hour, a buzzer beeps to remind you. The project runs off batteries, and uses an ATTiny85 chip, a pie...
by blippy
Mon Dec 31, 2018 11:14 pm
Forum: Graphics, sound and multimedia
Topic: A synthesizer/tone maker for the Pi
Replies: 2
Views: 277

Re: A synthesizer/tone maker for the Pi

The ATTiny85 chips are certainly fun to play with. I like the idea of small devices that can be powered by coin cells. I conceived of the synthesizer as a simple way of adding sound to a raspberry pi project without a lot of fuss. There is a sound Hat, but i thought I'd see if I could do something c...
by blippy
Mon Dec 31, 2018 9:09 pm
Forum: Graphics, sound and multimedia
Topic: A synthesizer/tone maker for the Pi
Replies: 2
Views: 277

A synthesizer/tone maker for the Pi

I finally wrote up my project for a "poor man's synthesizer/tone maker" for my Pi. DESCRIPTION What is it? A simplistic "synthesizer" that you can plug into your Arduino or Raspberry Pi. Use it when you want your project to produce a range of tones, and just want to use a tiny speaker instead of som...
by blippy
Tue Dec 25, 2018 6:31 pm
Forum: Graphics, sound and multimedia
Topic: Slightly glitchy sound producing tones via GPIO pins
Replies: 7
Views: 589

Re: Slightly glitchy sound producing tones via GPIO pins

Hmmm, interesting. The WiringPi softTone library is limited to 5kHz, which is quite a low value. Human hearing can go up to 20kHz, although mine is more like 10kHz. So it seems that it might be an OS thing, as you suggested. Interestingly, I am looking at the Ultibo website. I can see a few forum th...
by blippy
Tue Dec 25, 2018 6:06 pm
Forum: Graphics, sound and multimedia
Topic: Slightly glitchy sound producing tones via GPIO pins
Replies: 7
Views: 589

Re: Slightly glitchy sound producing tones via GPIO pins

I have noticed that WiringPi does have a Tone library http://wiringpi.com/reference/software-tone-library/ . Here's an example I concocted: #include <cassert> #include <wiringPi.h> #include <softTone.h> int main(void) { wiringPiSetup () ; pinMode (0, OUTPUT) ; auto ret = softToneCreate(0); assert(re...
by blippy
Tue Dec 25, 2018 5:08 pm
Forum: Graphics, sound and multimedia
Topic: Slightly glitchy sound producing tones via GPIO pins
Replies: 7
Views: 589

Re: Slightly glitchy sound producing tones via GPIO pins

The odd thing is that I did a similar thing with the Arduino tone library and even the ATTiny85 (with a hand-rolled tone library), using the same speaker and diode. It works fine. I then tried to translate the above code to Ultibo, which is a unikernel. I don't think it describes itself as a RTOS, b...
by blippy
Tue Dec 25, 2018 1:45 pm
Forum: Graphics, sound and multimedia
Topic: Slightly glitchy sound producing tones via GPIO pins
Replies: 7
Views: 589

Slightly glitchy sound producing tones via GPIO pins

I am trying to produce tones via GPIO pins. Here is the circuit: speaker.svg.png and here is the code: #include <wiringPi.h> //constexpr auto freq = 400; // Hz constexpr auto freq = 1000; // Hz constexpr auto d = 1e6/freq/2; // delay in microseconds void wait() { delayMicroseconds(d); } int main (vo...
by blippy
Thu Sep 20, 2018 7:26 pm
Forum: Interfacing (DSI, CSI, I2C, etc.)
Topic: I2C misreads of ATTiny85 slave
Replies: 1
Views: 458

Re: I2C misreads of ATTiny85 slave

OK. So I did a little tweak to config.txt to set the baudrate to 400000. This seems to fix the problem. The program reports numbers from 0...255, with no strange numbers cropping up. So, what's the conclusion? That the I2C was reading slower than the ATTiny85 was sending out signals, thereby causing...
by blippy
Thu Sep 20, 2018 6:39 pm
Forum: Interfacing (DSI, CSI, I2C, etc.)
Topic: I2C misreads of ATTiny85 slave
Replies: 1
Views: 458

I2C misreads of ATTiny85 slave

I'm fairly new to all this, so please try to keep things within my realm of understanding. I have set up an ATTiny85 (at 8MHz) as a slave. All it does is increment a counter each time it is called, and writes the counter out again. Here is the code: // Code for the ATtiny85 #define I2C_SLAVE_ADDRESS...
by blippy
Fri Mar 16, 2018 12:32 pm
Forum: Mathematica
Topic: Portfolio
Replies: 2
Views: 9181

Re: Portfolio

Yes I would be interested. What stockmarkets can it download from? I am new to Mathematica, so I can give very little in the way of advice. It uses Mathematica's Financial Entity, so I assume that its coverage is extensive. Yahoo Finance is effectively defunct, but Mathematica still works. It's not...
by blippy
Sat Feb 17, 2018 1:39 pm
Forum: Off topic discussion
Topic: How comes on a PI bluetooth works with my Micosoft Bluetooth Notebook Mouse 3000 but not with a Linux PC?
Replies: 1
Views: 791

How comes on a PI bluetooth works with my Micosoft Bluetooth Notebook Mouse 3000 but not with a Linux PC?

I have a Micosoft Bluetooth Notebook Mouse 3000, which works fine under Raspbian. However, i cannot connect it to my Ubuntu (or even Arch) vivoPC (Intel). Why? I would have thought it would have Just Worked (TM). The PC does have bluetooth, as evidenced by typing "rfkill list": 0: hci0: Bluetooth So...
by blippy
Fri Feb 16, 2018 7:36 pm
Forum: Beginners
Topic: Confused about voltages
Replies: 5
Views: 651

Confused about voltages

Am I right in thinking that all the GPIO pins are 3.3V tolerant, but not 5V tolerant? If so, isn't the 5V GPIO inviting a lot of trouble? For example, the blinkt uses the 5V pin. How comes it doesn't cause damage to the other pins that it uses for SPI communication? Does the blinkt have a built-in v...
by blippy
Tue Jan 16, 2018 7:18 pm
Forum: Interfacing (DSI, CSI, I2C, etc.)
Topic: ATTiny85 and Arduino IDE
Replies: 1
Views: 899

ATTiny85 and Arduino IDE

I saw a video on YouTube about programming ATTiny85 chips (or, indeed Atmel chips in general, including the Arduino]s chip) using avr-gcc and avrdude on a Pi. Another popular way of programming ATTiny85 chips is to use an Arduino and its IDE as an ISP. The Arduino IDE seems more capable than avr-gcc...
by blippy
Tue Dec 05, 2017 11:29 am
Forum: Bare metal, Assembly language
Topic: Ultibo core a bare metal environment for Raspberry Pi
Replies: 65
Views: 20931

Re: Ultibo core a bare metal environment for Raspberry Pi

While we understand the comparison with the simplicity of the 80's, our real aim is to create a 21st century platform that allows people to get creative without the necessity to start from scratch or to wrestle with the one size fits all approach of modern operating systems. I was reading an articl...
by blippy
Sun Dec 03, 2017 10:33 am
Forum: Bare metal, Assembly language
Topic: Ultibo core a bare metal environment for Raspberry Pi
Replies: 65
Views: 20931

Re: Ultibo core a bare metal environment for Raspberry Pi

Thanks for the heads-up on the Linux install. I wasn't aware of that. I am trying to transition away from Windows, so that's the kind of thing I'm looking for. I have in mind a couple of projects: * an accounts package. I already have written my own for Linux, a very simple affair. It would be inter...
by blippy
Sat Dec 02, 2017 10:21 pm
Forum: Bare metal, Assembly language
Topic: Ultibo core a bare metal environment for Raspberry Pi
Replies: 65
Views: 20931

Re: Ultibo core a bare metal environment for Raspberry Pi

Just came across this project today. Very interesting! This is probably the closest we're going to get to the feel of 80's computing. I managed to get a small program working. The feeling of control and low-level simplicity is appealing. I used the version for Windows, but I would like to get it wor...
by blippy
Sat Nov 18, 2017 3:15 pm
Forum: Other projects
Topic: Project idea for the CamJam EdiKit 1
Replies: 0
Views: 277

Project idea for the CamJam EdiKit 1

I bought a CamJam Edukit 1 recently as an intro to electronics using the RPi. I decided to create my own little project out of it. The idea is that you can toggle through the LEDs, and set a function to each LED. If you hold down a "long press", you activate the functionality that you associated wit...
by blippy
Tue Nov 14, 2017 10:43 am
Forum: General programming discussion
Topic: How do I smaple the volume?
Replies: 2
Views: 674

Re: How do I smaple the volume?

Thanks. Yes, that looks like the kind of thing I'm looking for.
by blippy
Mon Nov 13, 2017 7:08 pm
Forum: General programming discussion
Topic: How do I smaple the volume?
Replies: 2
Views: 674

How do I smaple the volume?

Suppose I want to sample the output volume of HDMI audio, e.g. 10 times a second. How do I do it?
by blippy
Fri Nov 03, 2017 3:14 pm
Forum: Mathematica
Topic: Portfolio
Replies: 2
Views: 9181

Portfolio

Yahoo Finance had a good service that allowed you to download share prices. Unfortunately, it seems to have been acting up lately, and is going the way of all things Yahoo, namely downhill. The good news is that Mathematica can download share prices. If anyone is interested in learning how Mathemati...

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