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by MarkTF
Wed Jun 05, 2019 8:51 pm
Forum: General discussion
Topic: Python code is being executed slowly on Pi 3 B+
Replies: 14
Views: 568

Re: Python code is being executed slowly on Pi 3 B+

Any help will be appreciated. I'd start by getting rid of passing results via global variables and explicitly return those values from each function definition. I suspect you might be generating some large arrays in the function calls that aren't actually used, but it's very hard to follow the prog...
by MarkTF
Thu May 16, 2019 12:43 pm
Forum: General discussion
Topic: RPi for button presser
Replies: 19
Views: 679

Re: RPi for button presser

. . . I am using 5V push pull Solenoid. . . . New update in this. O have changed my mosfet with logic level mosfet. The circuit got worked. But the solenoid heated up so badly. What should i do to my circuit if want to give 12V external supply? The obvious solution would be to use a solenoid rated ...
by MarkTF
Fri May 10, 2019 9:34 pm
Forum: General discussion
Topic: How to flash using Raspberry Pi 3
Replies: 7
Views: 445

Re: How to flash using Raspberry Pi 3

The open source "stm8flash" utility builds and runs on RaspberryPi, so flashing the STM8 via USB/STLink/SWIM is possible. The official STM8 development tools are all Windows, but "SDCC" supports STM8. If one wants to use the STM libraries, they'll have to be modified to be compatible with SDCC. Ther...
by MarkTF
Wed May 01, 2019 6:33 pm
Forum: General discussion
Topic: Automomous Pi - battery duration?
Replies: 2
Views: 182

Re: Automomous Pi - battery duration?

If one were to take the requirement "a battery which lasts as long as possible" literally, one might look at the largest capacity battery in existence. Unless it's been superseded this is the Hornsdale Power Reserve in Australia(1) at 129 MegaWatt Hours capacity. Ignoring a lot of real world issues ...
by MarkTF
Mon Apr 29, 2019 3:02 pm
Forum: General discussion
Topic: Problem with range of 433 Mhz receiver
Replies: 8
Views: 388

Re: Problem with range of 433 Mhz receiver

Signal levels are so weak, and the "modulation method" so simple, that even if 0.001% of a PI generated signal will overwhelm the receiver if its too close. It will simply "see" the 433MHz signal all the time. A "better receiver", (meaning more sensitive) will therefore not help. This isn't quite r...
by MarkTF
Mon Apr 15, 2019 12:08 am
Forum: General discussion
Topic: Retired old android smartphone's (HELP PLEASE)
Replies: 11
Views: 611

Re: Retired old android smartphone's (HELP PLEASE)

I've a stack of old Android phones. Some have been rooted to run the Linux on Android app and used as mini-file servers. I've used them for time-lapse photography via readily available apps from the playstore. Programmed via AppInventor for special purposes such as a bluetooth terminal, home tempera...
by MarkTF
Thu Apr 11, 2019 1:31 pm
Forum: General discussion
Topic: Run a pi3 on battery for a week ?
Replies: 7
Views: 421

Re: Run a pi3 on battery for a week ?

1) Measure or estimate the average power consumption of your system in Watts. You need to provide this many Watts for 7x24 hours so multiply to get 1 week power consumption in units of Watt hours. This link provides some guidance: https://www.pidramble.com/wiki/benchmarks/power-consumption . As an e...
by MarkTF
Sun Apr 07, 2019 1:00 pm
Forum: General discussion
Topic: Raspberry Pi 2 RS232 Wireless transmitter
Replies: 2
Views: 234

Re: Raspberry Pi 2 RS232 Wireless transmitter

The Raspberry Pi 2 doesn't have integral Bluetooth; the Pi Zero W and various Pi 3 models do. With those, certainly it would be possible to do what you suggest. A better solution might be to use a dedicated Bluetooth to serial device such as the ubiquitous HC-05. https://components101.com/wireless/h...
by MarkTF
Fri Mar 29, 2019 8:09 pm
Forum: General discussion
Topic: Measuring strength of vibration on SW-420 shock sensor using Python/Raspberry Pi.
Replies: 6
Views: 372

Re: Measuring strength of vibration on SW-420 shock sensor using Python/Raspberry Pi.

Yea I've been searching the web for a little while now and appears that it isn't possible to produce values on the Raspberry Pi like you can for the Arduino but instead just high and low like you said. I was just hoping this wasn't the case and someone knew how to do it. :( The second sketch in you...
by MarkTF
Fri Mar 29, 2019 3:10 pm
Forum: General discussion
Topic: Measuring Pi power with a Keweisi USB tester
Replies: 3
Views: 174

Re: Measuring Pi power with a Keweisi USB tester

These things work by measuring the voltage drop across a small value series resistor (current sense resistor) in line with the ground side of USB power. As a design decision one wants the voltage drop across this resistor at the maximum current (maybe 3 Amps) to be relatively small so that the volta...
by MarkTF
Fri Mar 29, 2019 2:19 pm
Forum: General discussion
Topic: How long will it stay on with a external battery?
Replies: 33
Views: 1142

Re: How long will it stay on with a external battery?

Thank you so much for all the help! :?: No one has actually given you an answer. The calculated example is exactly that - a mathematical answer and is worth the paper it’s written on (no disrespect meant). The calculated example(s) tell one the necessary parameters and the procedure to find the ans...
by MarkTF
Thu Mar 28, 2019 3:29 pm
Forum: General discussion
Topic: How long will it stay on with a external battery?
Replies: 33
Views: 1142

Re: How long will it stay on with a external battery?

20100 / 500 = 40.2 hours You're assuming this battery outputs 5V. If it doesn't, your trivial calculation is clear, simple and wrong. OP: We need more detail, like: 1: Do you really mean battery, or do you mean powerbank? 2: If battery, what chemistry and what voltage (or how many cells)? 3: Is it ...
by MarkTF
Thu Mar 28, 2019 3:07 pm
Forum: General discussion
Topic: Multiple Pi's to replace W10
Replies: 28
Views: 1100

Re: Multiple Pi's to replace W10

Hi All Still very dissatisfied with MS W10 (I sometimes wonder who owns my laptop!) I've found Linux, in it's differing forms, very difficult to master but Rpi I can manage. I wonder if it's possible to run multiple Pi's? It's possible to run a cluster with multiple RPis, but one would have to "mas...
by MarkTF
Wed Mar 27, 2019 7:42 pm
Forum: General discussion
Topic: Sterilization of Pi
Replies: 27
Views: 1449

Re: Sterilization of Pi

Sterilization methods and impact on electronics in medical devices: https://www.eetimes.com/document.asp?doc_id=1278906#
by MarkTF
Mon Mar 25, 2019 2:37 pm
Forum: General discussion
Topic: Two way pi to pi communication module
Replies: 2
Views: 144

Re: Two way pi to pi communication module

I thought about using LoRa, however it uses 1 way communication . . . LoRa modules are generally transceivers, that is they can either transmit a message or receive a message at a particular instant in time. Typically in a network one wants only one device at a time to be transmitting, but they can...
by MarkTF
Thu Mar 14, 2019 1:25 pm
Forum: General discussion
Topic: Stroboscope Guitar Tuner With RPi-Controlled LEDs
Replies: 7
Views: 530

Re: Stroboscope Guitar Tuner With RPi-Controlled LEDs

I hadn't known about this sort of tuner prior to your posting and now you've got me motivated to try to build up one of these. I've just placed an order for 1 Watt LEDs and have sketched out some drive circuit ideas to try out. When (if?) I get around to building something I'll post an update. I'll ...
by MarkTF
Wed Mar 13, 2019 1:56 pm
Forum: General discussion
Topic: USB Gadget mode; am I connected?
Replies: 20
Views: 1008

Re: USB Gadget mode; am I connected?

The device connection should be registered in dmesg. From the RPi command line dmesg | tail will show the most recent activity so doing this after connecting should give information about the attempt to connect and whether it was successful. Like all things Linux one can script around this to period...
by MarkTF
Tue Mar 12, 2019 2:17 am
Forum: General discussion
Topic: Stroboscope Guitar Tuner With RPi-Controlled LEDs
Replies: 7
Views: 530

Re: Stroboscope Guitar Tuner With RPi-Controlled LEDs

Generating this signal is pretty trivial with the pigpio library using the hardware PWM. Frequency accuracy would be equivalent to the processor crystal (something like 50 parts per million) plus the discrete tune frequency step error which is also small at these frequencies. As an example in Python...
by MarkTF
Thu Jan 24, 2019 5:01 pm
Forum: Advanced users
Topic: Need Help with hc-06 and android
Replies: 4
Views: 263

Re: Need Help with hc-06 and android

I do not know how to use Android Studio or anything similar and need help. I'd suggest taking a look at MIT AppInventor ( http://ai2.appinventor.mit.edu/ ) which is a simplified web-based Android App Development environment. If you have some programming experience you should be able to work through...
by MarkTF
Tue Jan 15, 2019 3:43 pm
Forum: General discussion
Topic: what charger from this two?
Replies: 9
Views: 730

Re: what charger from this two?

2 & 3 are within the specifications for the Pi3B+ (2.5 A or greater) and should work if they perform to specification. This is likely for these brands. The USB cable must high quality and the cable matters more than might be obvious. The problems caused by substandard power supplies and cables are o...
by MarkTF
Mon Jan 07, 2019 3:31 pm
Forum: General discussion
Topic: RISC-V
Replies: 135
Views: 8866

Re: RISC-V

RISC-V? DIY cpus for kids? Will a 6502 fit? All those retro cpus, number of transistors = ? number of LUTs https://en.wikipedia.org/wiki/Transistor_count. RISC-V is 10,000 -20,000 transistors? This FPGA could do a up to a Z80? There exist published open source FPGA core designs for a great many pro...
by MarkTF
Thu Jan 03, 2019 3:20 pm
Forum: General discussion
Topic: 2 x pi sending signal.
Replies: 5
Views: 191

Re: 2 x pi sending signal.

You won't damage GPIO pins connected together if they are inputs (duh?) or if any that are outputs are set to the same logic level. Thus you can emulate "open collector" (open drain) outputs on a RPi by setting the GPIO Pin to be an input when it is inactive and setting the GPIO Pin to be an output ...
by MarkTF
Wed Dec 19, 2018 3:42 pm
Forum: General discussion
Topic: pi one still supported?
Replies: 17
Views: 1060

Re: pi one still supported?

The original Pi was more sensitive to power supply irregularities than later versions so it would be worth trying different USB power brick and cable combinations.
by MarkTF
Thu Nov 29, 2018 6:44 pm
Forum: General discussion
Topic: Using hot glue to mount 3B ?
Replies: 7
Views: 909

Re: Using hot glue to mount 3B ?

Would Velcro Tape work? That would make it far easier to remove the Pi if necessary.
by MarkTF
Thu Nov 29, 2018 6:31 pm
Forum: General discussion
Topic: Arduino how TTL Converter
Replies: 11
Views: 609

Re: Arduino how TTL Converter

I'm not entirely clear on the question you're asking, but this might be the answer: The Arduino Uno has a USB to Serial converter on the board that is normally used to communicate between a PC and the Atmel microcontroller. If one removes the Atmel microcontroller (on socketed boards) or disables th...

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