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by mark3112
Wed Nov 06, 2019 6:28 pm
Forum: General discussion
Topic: Interfacing FPGA with my raspberry Pi !
Replies: 5
Views: 298

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: 298

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: 490

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: 678

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: 678

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: 1109

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: 545

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: 5892

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: 911

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: 489

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: 1314

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: 686

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: 18
Views: 8303

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: 326

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: 1138

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: 1138

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: 1138

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: 6099

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: 18413

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
by mark3112
Tue May 15, 2018 2:46 pm
Forum: Beginners
Topic: Changing PIGPIO SPI timing
Replies: 2
Views: 361

Re: Changing PIGPIO SPI timing

Have you tried both SCLK modes in spiFlags as clocking the data on the wrong edge will cause odd data.
Otherwise info on the device and your code would be helpful.
by mark3112
Tue May 15, 2018 12:52 pm
Forum: Raspbian
Topic: 3B+ dhclient eth0 problem
Replies: 0
Views: 239

3B+ dhclient eth0 problem

Hi I am running 2018-04-18-raspbian-stretch-lite on a 3B and 3B+ I need to Spoof the MAC Address so use the commands below. On the 3B it works as it always has. On the 3B+ the last command either responds with Too few Arguments or just hangs. Is there some additional argument required by the 3B+? su...
by mark3112
Sat May 12, 2018 10:23 pm
Forum: Off topic discussion
Topic: Connecting and send Data from a FPGA to the Raspberry
Replies: 3
Views: 2760

Re: Connecting and send Data from a FPGA to the Raspberry

SPI.
I use an FPGA as the master, communicating a STM32F432.
But as the Pi has to be the master then you are somehow going to have to set the Pi to initiate the transfer. But its do’able.
by mark3112
Sat May 12, 2018 9:30 pm
Forum: General discussion
Topic: Communication between multiple RPI installations in Home Automation System
Replies: 3
Views: 684

Re: Communication between multiple RPI installations in Home Automation System

I’m have a Home Automation System and am lucky in having it sponsored by my employer as I work in their R&D dept. The way I see it, having the Control Elements is one thing, controlling the mains power to the end points, is another. I see you refer to relays but to me that’s way too digital. How abo...
by mark3112
Sat May 12, 2018 8:42 pm
Forum: General discussion
Topic: Effective way to communicate Raspberry Pi with STM32
Replies: 13
Views: 6099

Re: Effective way to communicate Raspberry Pi with STM32

If they are close together, just use I2C, SPI or RS-232.
by mark3112
Fri May 11, 2018 8:23 pm
Forum: General discussion
Topic: Effective way to communicate Raspberry Pi with STM32
Replies: 13
Views: 6099

Re: Effective way to communicate Raspberry Pi with STM32

CAN could be an option or RS-485.
The STMF4xx range normally have two CAN Controllers built in, so would only need an Interface Chip (see MCP2551 as an example) and the pi end could use the MCP2515 on an SPI port (and another Interface Chip).

https://en.wikipedia.org/wiki/CAN_bus

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