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by mark3112
Sat Jan 18, 2020 5:59 pm
Forum: General discussion
Topic: Raspberry and FPGA
Replies: 17
Views: 979

Re: Raspberry and FPGA

As chipace said, much depends on what you mean by "program the FPGA". I worked on a project where a STM32 held the configuration information and used this to create the VHDL file that was uploaded to the FPGA’s configuration EEPROM. Normally this would be done via JTAG but the configuration EEPROM i...
by mark3112
Mon Dec 30, 2019 12:44 am
Forum: General programming discussion
Topic: Javascript – copy file – possible?
Replies: 4
Views: 507

Re: Javascript – copy file – possible?

“configure Apache to serve everything from a web root on your other media” That I like, will look into it. Thanks. I was going for a more primitive approach. When the page loads create a flag file, let the C code find the file and move the temperature data. Once it’s displayed, delete the files. The...
by mark3112
Sun Dec 29, 2019 7:27 pm
Forum: General programming discussion
Topic: Javascript – copy file – possible?
Replies: 4
Views: 507

Re: Javascript – copy file – possible?

It’s been a long time since I did anything with HTML and Javascript is entirely new to me so please excuse me if I get things mixed up. I am using Apache2 on the Pi as the web server and accessing it with Firefox on my phone. The program running on the Pi that creates the data, controls my (solid fu...
by mark3112
Sun Dec 29, 2019 4:16 pm
Forum: General programming discussion
Topic: Javascript – copy file – possible?
Replies: 4
Views: 507

Javascript – copy file – possible?

I have a data logger program on my Pi monitoring my central heating. Every minute it updates a .csv file with the temperatures. I want to be able to access the data via a webpage using Dygraphs. Dygraphs can only access the file if it is in the www folder but I don’t want to store the data on the SD...
by mark3112
Thu Nov 28, 2019 8:54 pm
Forum: Beginners
Topic: Slowly Increase and Decrease LED Intensity?
Replies: 10
Views: 860

Re: Slowly Increase and Decrease LED Intensity?

GPIO PWM into a transistor that controls the current to the LED’s. If you don’t use the transistor there is a very good chance you will kill the pi.

https://electronicshobbyists.com/raspbe ... rvo-motor/
by mark3112
Thu Nov 21, 2019 10:56 am
Forum: Beginners
Topic: Measuring frequency in a voltage signal
Replies: 11
Views: 613

Re: Measuring frequency in a voltage signal

As per Joan’s suggestion, try a zero crossing detector.
http://www.ti.com/lit/an/snoa999/snoa999.pdf
by mark3112
Wed Nov 06, 2019 6:28 pm
Forum: General discussion
Topic: Interfacing FPGA with my raspberry Pi !
Replies: 5
Views: 1106

Re: Interfacing FPGA with my raspberry Pi !

How fast can you transfer data? Without checking the FPGA’s specs I think its internal maximum clock is about 400MHz. So, let’s play safe and divide by 2, so 200Mbs for the Cyclone III chip? Can you explain more ? Yep, what do you want to know? But I have only worked with Altera parts, many years ag...
by mark3112
Tue Nov 05, 2019 1:22 pm
Forum: General discussion
Topic: Interfacing FPGA with my raspberry Pi !
Replies: 5
Views: 1106

Re: Interfacing FPGA with my raspberry Pi !

SPI works for me using a pair of shift registers. I have two 8 bit output latches and switch between them when data is being sent. That way one can be loaded whilst the other is live on the shift register.
by mark3112
Mon Jun 17, 2019 10:59 am
Forum: General discussion
Topic: How to make gpio as chipselect
Replies: 3
Views: 611

Re: How to make gpio as chipselect

I used to use the dtoverlay command I don’t know if it’s still current though. Name: spi1-3cs Info: Enables spi1 with three chip select (CS) lines and associated spidev dev nodes. The gpio pin numbers for the CS lines and spidev device node creation are configurable. N.B.: spi1 is only accessible on...
by mark3112
Wed Feb 20, 2019 7:28 pm
Forum: Interfacing (DSI, CSI, I2C, etc.)
Topic: Self made canbus board only working at 500kbs but not 1 Mbs
Replies: 4
Views: 759

Re: Self made canbus board only working at 500kbs but not 1 Mbs

For a minimal CAN network take a look at Keil’s A Tiny Network without Transceiver ICs (bottom of page 4):

http://www.keil.com/download/files/canprimer_v2.pdf
by mark3112
Wed Feb 20, 2019 7:15 pm
Forum: Interfacing (DSI, CSI, I2C, etc.)
Topic: Self made canbus board only working at 500kbs but not 1 Mbs
Replies: 4
Views: 759

Re: Self made canbus board only working at 500kbs but not 1 Mbs

I’ve not used the MCP2551 and normally use SN65HVD251 but guess the CAN interface is the same. What are R1 & R2 for (the whole idea of CAN is that it is robust in noisy environments)? I would also lose R6 & R7 (at least during the testing phase). The other thing that jumps out at me is the 2515 is f...
by mark3112
Wed Jan 09, 2019 8:42 pm
Forum: General discussion
Topic: Any recommendations for a pre-amp/preamp
Replies: 7
Views: 1744

Re: Any recommendations for a pre-amp/preamp

My 40 year old Pioneer SA-9800 died a few months ago, I was about to buy a new amp but out of curiosity I had a look on the net to see if there were any second hand ones. There was for $2500. Which made me think repairing it was a better alternative than scrapping it. If you fancy trying to fix it, ...
by mark3112
Fri Jul 06, 2018 3:46 pm
Forum: Advanced users
Topic: Measuring an internal distance
Replies: 4
Views: 653

Re: Measuring an internal distance

Possibly a dumb question but I’m curious. Why do you need to measure the inside diameter? As the pipe expands, the outside must expand as well. OK, the wall diameter will reduce very slightly but would make measuring easier. If you can measure the outside, see laser diameter gauge (scan a laser acro...
by mark3112
Mon Jun 25, 2018 6:53 pm
Forum: Wanted
Topic: Engineer needed to build breakout boards - Old "AirPi" project
Replies: 9
Views: 6403

Re: Engineer needed to build breakout boards - Old "AirPi" project

“we are looking to build our own sensors based on an RPI or similar platform” I’m with drgoff, that’s way too general. Are you looking to build a custom sensor module or a PCB housing commercially available components? The links don’t help when you try and dig down to the details and end up with a p...
by mark3112
Wed Jun 20, 2018 8:18 pm
Forum: General discussion
Topic: Using raspberry pi to measure angle newbie
Replies: 5
Views: 1232

Re: Using raspberry pi to measure angle newbie

Linear potentiometer and an ADC?
Type “Linear-Position-Sensor” into ebay.
by mark3112
Mon Jun 18, 2018 1:04 pm
Forum: Automation, sensing and robotics
Topic: Playing with raspberry pi and negative voltage in a car
Replies: 2
Views: 555

Re: Playing with raspberry pi and negative voltage in a car

At a guess it looks like the +/- indicate the Active Level of the signal.
So The Brake Status is true when + (12V)
Trunk Status is true when – (0V)
by mark3112
Fri Jun 15, 2018 7:13 pm
Forum: Troubleshooting
Topic: High RPI 3 board failures
Replies: 11
Views: 1518

Re: High RPI 3 board failures

The company I work for has sold about 500 Pi based Lighting Control Desks and expect to move about 1000 this year (want to test ruggedness? Give it to the Stage Crew). A new Pi product (office type lighting controller) that I am involved in has just reached the point of bulk deliveries to installers...
by mark3112
Wed Jun 13, 2018 7:40 pm
Forum: General discussion
Topic: What is configuration of wiring connection use db9 serial port from output device to RPi 3 by IDC10 head connector
Replies: 5
Views: 875

Re: What is configuration of wiring connection use db9 serial port from output device to RPi 3 by IDC10 head connector

Try a search on the phrase

Ultra Compact RS232 to TTL Converter with Male DB9

and you will probably want some conection leads to connect it to the header.
by mark3112
Wed Jun 13, 2018 3:25 pm
Forum: Automation, sensing and robotics
Topic: Dali Light Management with RaspberryPi
Replies: 16
Views: 10289

Re: Dali Light Management with RaspberryPi

I use a Microchip DALI Interface (DM160215) that works OK but its USB to Windoze (USB HID).
Have a look at DM160214-1, No comms channel but if you can rework the PIC code perhaps you could implement something.
by mark3112
Tue Jun 12, 2018 5:44 pm
Forum: Advanced users
Topic: How to Use Raspberry Pi to start a program on a external Computer
Replies: 3
Views: 360

Re: How to Use Raspberry Pi to start a program on a external Computer

Possible? Don’t see why not. How much finesse do you want?
What sort of control? What other program?
Quick and dirty solution. Have a PowerShell script on the PC that occasionally pings the Pi.
When it responds.... (PowerShell gives you .NET and a relatively simple interface)
by mark3112
Wed Jun 06, 2018 6:19 pm
Forum: Interfacing (DSI, CSI, I2C, etc.)
Topic: Interrupt from PICAN2 does not work
Replies: 10
Views: 1288

Re: Interrupt from PICAN2 does not work

Looking at the pigpio documentation: “gpioSetAlertFunc - [Polled] The GPIO are sampled at a rate set when the library is started. gpioSetISRFunc – [Event Driven] The GPIO is exported, set to be an input, and set to interrupt on the given edge and timeout.” Although I’m sure Joan could supply a bette...
by mark3112
Tue Jun 05, 2018 6:51 pm
Forum: Interfacing (DSI, CSI, I2C, etc.)
Topic: Interrupt from PICAN2 does not work
Replies: 10
Views: 1288

Re: Interrupt from PICAN2 does not work

“The Interrupt on GPIO25 works fine from PICAN2, but it might be too fast for wiringPi to find it.” I don’t understand that, how can the signal be too fast when it’s software that resets the INT Line on MCP2515 - GPIO25? It could be a driver is reading the data and resetting the INT line? I drive 4 ...
by mark3112
Tue Jun 05, 2018 9:21 am
Forum: Interfacing (DSI, CSI, I2C, etc.)
Topic: Interrupt from PICAN2 does not work
Replies: 10
Views: 1288

Re: Interrupt from PICAN2 does not work

Have you set the RXnIE bit in the CANINTE register? I have a pi connected to 4 MCP2515 and initially used interrupts and wiringPI. A problem I hit straight away was the restriction of a maximum of two interrupts and the fact the interrupt handling routine was itself interruptable, which caused havoc...
by mark3112
Thu May 17, 2018 8:56 am
Forum: General discussion
Topic: Effective way to communicate Raspberry Pi with STM32
Replies: 13
Views: 8114

Re: Effective way to communicate Raspberry Pi with STM32

As you are connecting directly you don’t need RS-232 line drivers.
If the devices are very close just connect them TX-RX and RX-TX.
If they are not close you could use differential line drivers i.e. see SN65LVDS180
by mark3112
Wed May 16, 2018 6:10 pm
Forum: Off topic discussion
Topic: What was your 1st game?
Replies: 49
Views: 19375

Re: What was your 1st game?

Heater - “Lunar Lander on the Commodore PET” LOL. Been there, done that. But only during college hours.

First REAL game – Elite, on the BBC Micro

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