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by CRP99
Mon Apr 14, 2014 4:16 pm
Forum: C/C++
Topic: wiringPiISR interrupts
Replies: 1
Views: 3532

wiringPiISR interrupts

Hello all, I am having a bit of trouble with trying to implement some edge-triggered events in wiringPi with the "wiringPiISR()" command. I have viewed the included example (isr.c) and have been able to execute a program of my needs for one interrupt event. However, I am trying to implement two inte...
by CRP99
Sun Mar 23, 2014 10:51 pm
Forum: Advanced users
Topic: Full Speed or Low Speed USB Isochronous Data Transfers
Replies: 5
Views: 1588

Re: Full Speed or Low Speed USB Isochronous Data Transfers

I am having trouble trying to find where the PL011 UART is. Is that using GPIO pin 11 configured as an alternate UART receive (RX) pin? Also, I am having some trouble getting the Pi to read incoming serial data in general. I'm not getting anything. I'm not sure if it is something incorrect with my w...
by CRP99
Thu Mar 20, 2014 6:12 pm
Forum: Beginners
Topic: Using incoming UART data for processing in other application
Replies: 3
Views: 1003

Re: Using incoming UART data for processing in other applica

Hi techpaul. Yes, I do recall that now. I kind of confused myself in what i had been looking to do previously. Since you last heard from me, I was working on trying to connect an external, USB-capable PIC18 microcontroller to the Pi, so that I would be able transfer the data via USB. I had figured t...
by CRP99
Thu Mar 20, 2014 2:37 pm
Forum: Beginners
Topic: Using incoming UART data for processing in other application
Replies: 3
Views: 1003

Using incoming UART data for processing in other application

I am trying to get the Raspberry Pi to do some processing on some sampled audio (the new gpu_fft looks very promising). I was wondering if I were to send the sample data via a serial connection (UART), would I be able to directly implement the incoming data in some data processing applications direc...
by CRP99
Thu Mar 20, 2014 2:01 pm
Forum: Advanced users
Topic: Serial Communication over USB
Replies: 4
Views: 2638

Re: Serial Communication over USB

Check out the wiringSerial library for wiringPi. That library lets you perform serial operations with the GPIO. There is a relatively simple implementation built in for serial to USB. It's all written in C.

https://projects.drogon.net/raspberry-p ... l-library/
by CRP99
Wed Mar 19, 2014 11:13 pm
Forum: Advanced users
Topic: Full Speed or Low Speed USB Isochronous Data Transfers
Replies: 5
Views: 1588

Re: Full Speed or Low Speed USB Isochronous Data Transfers

Oh, I didn't realize that you could use speeds that aren't standard defined baud rates (9600, 19200, 115200, etc.).
You can crank it up with custom baud rates?
by CRP99
Wed Mar 19, 2014 10:37 pm
Forum: Advanced users
Topic: Full Speed or Low Speed USB Isochronous Data Transfers
Replies: 5
Views: 1588

Re: Full Speed or Low Speed USB Isochronous Data Transfers

In the current driver it is 1880 bytes/sec, ... ... so with the current driver, if we are speaking in terms of bit rates, 1880 bytes/sec would be 15040 bps, correct? Considering these bandwidth limitations, it would seem that UART can handle faster data transfer rates than the current USB driver ca...
by CRP99
Wed Mar 19, 2014 7:02 pm
Forum: Advanced users
Topic: Full Speed or Low Speed USB Isochronous Data Transfers
Replies: 5
Views: 1588

Full Speed or Low Speed USB Isochronous Data Transfers

Hello everyone, I wouldn't really consider myself an "advanced user", but USB is rather an advanced topic, so I figured this would be a proper place for it. I am working on a project that will require me to perform fairly high-speed, continuous data transferring. I have examined the other hardware i...
by CRP99
Tue Mar 04, 2014 4:33 pm
Forum: Beginners
Topic: Supplying a clock for an ADC ic
Replies: 49
Views: 10101

Re: Supplying a clock for an ADC ic

I thought capturing the data in "real-time" was the important part of your audio sampling. Can't you take all the time you need for the "MIDI" part? Well, the plan is to obtain a real-time (or very near real-time) output data stream of MIDI commands that correspond to the pitch and volume informati...
by CRP99
Tue Mar 04, 2014 2:53 am
Forum: Beginners
Topic: Supplying a clock for an ADC ic
Replies: 49
Views: 10101

Re: Supplying a clock for an ADC ic

Directly addressing the memory of another microcontroller is a complex task possible to emulate at SLOW speeds for SMALL blocks of memory, large data sets would be a nightmare unless you want to design your own Pi special version. To do this even in quad core processors need lots of logic and dedic...
by CRP99
Mon Mar 03, 2014 4:36 pm
Forum: Beginners
Topic: Supplying a clock for an ADC ic
Replies: 49
Views: 10101

Re: Supplying a clock for an ADC ic

As it would seem that performing sampling on the Pi would not be practical in my case due to its CPU intensiveness (considering I also will need to perform signal analysis with FFT implementation), an additional auxiliary device to process the samples would be needed. For example, what if I were to ...
by CRP99
Mon Mar 03, 2014 4:00 pm
Forum: Interfacing (DSI, CSI, I2C, etc.)
Topic: An experiment in bit-banging SPI
Replies: 22
Views: 21504

Re: An experiment in bit-banging SPI

Make we wonder why people actually would want high sample rates on the Pi. You can't do anything useful with them once you've got them! Indeed, that would seem to be the case. :cry: Having the Pi handle real-time sample data does not seem to be a very practical implementation. I have had some other...
by CRP99
Mon Mar 03, 2014 1:42 pm
Forum: Beginners
Topic: Supplying a clock for an ADC ic
Replies: 49
Views: 10101

Re: Supplying a clock for an ADC ic

I have done what will probably be my final test for which I'll start a new post. Ok, I will take a look at that when you do. I squeezed the timings down and seem to be getting accurate results for sampling at 25ksps (40 micros per transaction) with 50% CPU. In your approach, you're getting 50% CPU ...
by CRP99
Thu Feb 27, 2014 7:38 pm
Forum: Beginners
Topic: Supplying a clock for an ADC ic
Replies: 49
Views: 10101

Re: Supplying a clock for an ADC ic

What about this 8-bit flash ADC I found from Texas Instruments. http://www.ti.com/product/tlc5540 Unless I am missing something, it seems to me as though it doesn't use or require a data interface for operation. It only seems to operate in response to an enable and a clock signal. Maybe, a PLL would...
by CRP99
Thu Feb 27, 2014 3:08 pm
Forum: Beginners
Topic: Supplying a clock for an ADC ic
Replies: 49
Views: 10101

Re: Supplying a clock for an ADC ic

As a 100kHz I2C device its spec is that the maximum analog sampling rate is 11kHz burst rate (for all channels read so 1 channel only is 11kHz to 4 channels are at 2.525kHz each) by continually reading in one I2C transaction. Which is well below the requirements for this type of application. I ran ...
by CRP99
Thu Feb 27, 2014 2:45 pm
Forum: Beginners
Topic: Supplying a clock for an ADC ic
Replies: 49
Views: 10101

Re: Supplying a clock for an ADC ic

From what i have researched about analog guitar synthesizers and existing methods of guitar to MIDI transformations prior to my endeavor, generally what is used to determine the fundamental pitch (first harmonic) is zero-crossing detection. It was found to produce more reliable results when analyzin...
by CRP99
Thu Feb 27, 2014 2:33 am
Forum: Beginners
Topic: Supplying a clock for an ADC ic
Replies: 49
Views: 10101

Re: Supplying a clock for an ADC ic

Not really as your goal posts seem to be moving from one to 6 channels. From unknown sensors, which may or may not be amplified to same voltage ranges, for unknown data width. To be a little bit more specific about what I am trying to do, I am trying to design a device that will enable a guitar to ...
by CRP99
Wed Feb 26, 2014 11:34 pm
Forum: Beginners
Topic: Supplying a clock for an ADC ic
Replies: 49
Views: 10101

Re: Supplying a clock for an ADC ic

Some multi channel ADCs will convert each channel in turn while CS is low. However to get your required sample rates of 10kHz plus even on one channel for more than 10ms on a Pi using SPI is nigh on impossible to guarantee the timing without external hardware/microcontroller designed for such purpo...
by CRP99
Wed Feb 26, 2014 11:24 pm
Forum: Beginners
Topic: Supplying a clock for an ADC ic
Replies: 49
Views: 10101

Re: Supplying a clock for an ADC ic

NO the characterisation of the programming commanding of ADC samples via the SPI interface, the ADC will convert samples as commanded when commanded, if you command at irregular times (as will happen on an OS like Linux without timed DMA support), then your sampling is not continuous whatever you m...
by CRP99
Wed Feb 26, 2014 11:13 pm
Forum: Beginners
Topic: Supplying a clock for an ADC ic
Replies: 49
Views: 10101

Re: Supplying a clock for an ADC ic

Actually, I think some of them have internal multiplexers (for example: http://www.ti.com/lit/ds/symlink/tlv1570.pdf), so they might possibly deal with that internally on there own, depending on how many inputs are desired.
by CRP99
Wed Feb 26, 2014 11:06 pm
Forum: Beginners
Topic: Supplying a clock for an ADC ic
Replies: 49
Views: 10101

Re: Supplying a clock for an ADC ic

SPI is almost certainly best for what you want (high sample rates from multiple devices). Well, what about your thoughts on using one ADC chip with 6 or more input channels (they have some of those with SPI). I figured that could possibly allow me to interface with one device, as opposed to having ...
by CRP99
Wed Feb 26, 2014 10:31 pm
Forum: Beginners
Topic: Supplying a clock for an ADC ic
Replies: 49
Views: 10101

Re: Supplying a clock for an ADC ic

I rarely use SPI. What other types of interfaces can the Pi use? I know it can deal with I2C, but I'm pretty sure that this is a slower method than SPI. There are ways to multiplex the channel selects so you can have, say, 8 ADCs. That'll require an additional chip. What kind of chip would do this?...
by CRP99
Wed Feb 26, 2014 10:12 pm
Forum: Beginners
Topic: Supplying a clock for an ADC ic
Replies: 49
Views: 10101

Re: Supplying a clock for an ADC ic

That's good to hear if that is indeed the case. Then, I at least have the a conceptual idea of how it all should work. Granted, I don't know what actually goes on as far as the communication between the ADC and the Pi over the SPI Data-In and Data-Out lines. I know what they need to accomplish in th...
by CRP99
Wed Feb 26, 2014 8:43 pm
Forum: Beginners
Topic: Supplying a clock for an ADC ic
Replies: 49
Views: 10101

Re: Supplying a clock for an ADC ic

... so much for what I thought was a simple issue :lol: It's all good though. Last post seemed a bit daunting at first, but after taking some time to break it down, and try to gain more understanding of the SPI interface, I think I understand what it is I need to do a bit better. My knowledge base m...
by CRP99
Sat Feb 22, 2014 5:44 pm
Forum: Beginners
Topic: Supplying a clock for an ADC ic
Replies: 49
Views: 10101

Re: Supplying a clock for an ADC ic

I am testing out a few different ADC chips, so in each case, whether the clock is a sampling clock or a data transfer clock is something I need to examine, as I was not aware that these could be set independently from each other. Most of the chips have a pin labeled "SCLK" or "CLK", which is what wa...

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